Second Hinode Science Meeting
Beyond Discovery – Toward Understanding

29 September- 3 October 2008
Boulder, Colorado USA

Abstracts

Authors: : Lucia Abbo and Alan Gabriel

Title: Coronal hole study through the solar atmosphere: from the chromosphere up to coronal layers

Abstract: We analyse intensities and velocities over a range of temperatures, covering the chromosphere to the corona, within polar coronal holes. Using observations from EIS and SOT on Hinode and CDS on SOHO, we examine the velocity fields over this region of the lower corona, with the aim of better understanding the onset region of the fast solar wind during the current solar minimum period. Existing observations are being studied and newer observations are currently under way.

Session: Source of the Solar Wind/CME

Authors: : Tayeb Aiouaz

Title: Evidences of Relentless Reconnections at Boundaries of Supergranular Network Lanes

Abstract: Doppler-shift properties of the solar transition region (TR) and low corona are investigated in relation to the underlying chromospheric supergranular network, with particular regard to the role of the magnetic field. EUV line properties were obtained from a large raster scan of the solar transition region and corona acquired by the UV/EUV spectrometer SUMER on board SOHO. The observed regions include an equatorial coronal hole, as well as surrounding quiet Sun areas. I present correlations between the chromospheric network, and the N IV (765.15 Ă‚), O IV (790.19 A), S V (786.50 A), O V (760.45 A) Doppler shifts in quiet Sun and coronal hole. It is established that the maximum inflow (redshift) at transition region temperatures appears statistically toward the center of the network lanes in the quiet Sun areas and toward the boundary of the network lanes in the coronal hole part. Furthermore, while the strong red-shifts in the TR lines complement spatially blue-shifts from the low corona (Ne VIII, 770.41 A) in a puzzle-like pattern, bi-directional flows (i.e. cospatial strong red/blue-shits in the TR/Corona) appear predominantly in the coronal hole. The bi-directional flows happen almost systematically at boundaries of magnetic field concentrations when compared to the reconstructed magnetogram from a MDI/SOHO series. These results allow to propose for the first time a coherent interpretation involving a single driver for almost thirty years of unexplained statistical Doppler shift variations in the transition region and corona for quiet Sun and coronal hole. The proposed scenario involves reconnections between the strong network magnetic field and continuously advected weak field from the supergranular cell interior.

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Author: : Richard Altrock

Title: Solar Torsional Oscillations and Their Relationship to Coronal Activity

Abstract: Torsional Oscillations (TO) were first observed on the surface of the Sun as waves of small deviations from differential rotation, which propagate from high latitudes to the equator over solar-cycle time scales. More recently they have been inferred from observations of solar global oscillations to occur in the convection zone. Long-lived brightenings in the corona have also been observed to propagate from near the poles to the equator over similar time scales. This paper will discuss the relationship between TO as observed on the solar surface and in the convection zone and brightenings in the corona. We find that there is an apparent connection between these two phenomena that extends from the equator to latitudes as high as 70 to 80 degrees. This may imply control of both of these phenomena by the driver of the solar cycle (the solar dynamo) and thus place observational constraints on dynamo models. R. C. Altrock was supported by the Air Force Office of Scientific Research.

Session: Bringing Modeling and Obvservations Together

Author: : Spiro K. Antiochos

Title: CME Initiation

Abstract: Coronal mass ejections are the largest and most energetic form of transients that connect the corona to the solar wind. They are critically important both for understanding the physical mechanisms of explosive solar activity and for predicting space weather. It is now widely accepted that CMEs/eruptive flares represent the explosive release of magnetic energy stored in the corona., but the initiation process is still far from understood and is currently a topic of intense debate. In this presentation I will review CME theories and present the latest results from 3D numerical modeling of CME initiation. I will focus, in particular, on the breakout model, but many of the results hold in general. The implications of these results for understanding coronal/solar wind structure and dynamics and for interpreting the Hinode observations will be discussed.

This work was supported in part by the NASA HTP, SR&T, and TR&T programs.

Session: Bringing Modeling and Obvservations Together

Author: : Patrick Antolin

Title: Predicting observational signatures of coronal heating by Alfvén waves and nanoflares.

Abstract: Alfvén waves can dissipate their energy by means of nonlinear mechanisms, and constitute good candidates to heat and maintain the solar corona to the observed few million degrees. Another appealing candidate is the nanoflare-reconnection heating, in which energy is released through many small magnetic reconnection events. Distinguishing the observational features of each mechanism is an extremely difficult task. On the other hand, observations have shown that energy release processes in the corona follow a power law distribution in frequency whose index may tell us whether small heating events contribute substantially to the heating or not. In this work we show a link between the power law index and the operating heating mechanism in a loop. We set up two coronal loop models: in the first model Alfvén waves created by footpoint shuffling nonlinearly convert to longitudinal modes which dissipate their energy through shocks; in the second model numerous heating events with nano flare-like energies are input randomly along the loop, either distributed uniformly or concentrated at the footpoints. Both models are based on a 1.5-D MHD code. The obtained coronae differ in many aspects, for instance, in the flow patterns along the loop and the simulated intensity profile that Hinode/XRT would observe. The intensity histograms display power law distributions whose indexes differ considerably. This number is found to be related to the distribution of the shocks along the loop. We thus test the observational signatures of the power law index as a diagnostic tool for the above heating mechanisms and the influence of the location of nanoflares.

Session: Perspectives on the Physics of Coronal Loops

Authors: : I. Arregui, J. Terradas, R. Oliver, J.L. Ballester

Title: Damping of fast magnetohydrodynamic oscillations in quiescent filament threads

Abstract: High-resolution observations provide evidence about the existence of small-amplitude transverse oscillations in solar filament fine structures. These oscillations are believed to represent fast magnetohydrodynamic (MHD) waves and the disturbances are seen to be damped in short time-scales of the order of 1 to 4 periods. We propose that, due to the highly inhomogeneous nature of the filament plasma at the fine structure spatial scale, the phenomenon of resonant absorption is likely to operate in the temporal attenuation of the observed motions. By considering transverse inhomogeneity in a straight flux tube model we find that, for density inhomogeneities typical of filament plasmas, the considered mechanism provides decay times of a few oscillatory periods only, thus consistent with the observed time-scales.

Session: Bringing Modeling and Obvservations Together

Authors: : Markus J. Aschwanden

Title: Heating and Cooling of Coronal Loops (Invited Talk)

Abstract: The physical evolution of impulsively-heated coronal loops and their subsequent cooling is now explored in great detail, using multi-wavelength data in soft X-rays and EUV, in particular with HINODE/EIS, XRT, STEREO/EUVI, TRACE, and RHESSI. With stereoscopic triangulation we can reconstruct the 3D geometry of active regions with unprecedented detail, comprising up to 10⁵ loops per active region. Using some newly developed analytical approximations of the density n(s,t) and temperature evolution T(s,t) of impulsively-heated coronal loops we are now able to reproduce the observed evolution of light curves in soft X-rays, hard X-rays, and EUV and to quantify their non-equilibrium dynamics in terms of a common framework, arriving at a unified model of their hydrodynamic evolution.

Session: Perspectives on the Physics of Coronal Loops

Authors: Raphael Attie, Davina Innes

Title: Coronal heating from not-so-quiet-Sun explosive events.

Abstract: Coaligned observations between Hinode and Soho were made from the photosphere to the lower corona in the quiet Sun. We present a new description of the couplings between the plasma and the magnetic field during small explosive events. They are first detected using transition region lines in SUMER/Soho spectra and in X-ray images with XRT/Hinode. Photospheric flows are then calculated using the FG-SOT/Hinode images of the granulation in Blue Continuum. They are compared with the magnetic data from both MDI/SoHo and SP-SOT/Hinode. In this way, we reveal another contribution of quiet-Sun eruption events in coronal heating.

Session: Hinode Perspectives on Coronal/Chromoshperic Heating

Author: :Deborah Baker

Title: Upflows in an active region-coronal hole complex - enigma or CME precursor?

Abstract: We investigate the plasma flows resulting from the interaction between a mature active region (AR) and a surrounding equatorial coronal hole (CH) observed by Hinode's EIS, XRT and SOT instruments from 15 to 18 October 2007. For the first 3 days, EIS velocity maps showed outflows at the AR's eastern and western edges which were consistently between 5 and 10 km/sec whereas downflows of up to 30 km/sec were seen in AR loops. However, on 18 October, velocity profiles of hotter coronal lines (Fe X, Fe XI, Fe XII and Fe XIII) reveal an intensification in outflow velocities of up to 16 km/sec at the AR's western footpoint 6.5 hours prior to a sigmoidal CME eruption. We compare the AR's plasma flows with both 2.5D and 3D MHD numerical simulations of the scenario, finding that slow jet-like outflows on the eastern side are a direct consequence of reconnection between the AR's closed loops and the oppositely oriented open field of the surrounding CH. A by-product of the reconnection is flows along the newly opened field lines on the AR's western side, driven by an increase in the gas pressure gradient resulting from reconnection of dense loops and evacuated field. We believe the intensification of outflow velocities observed at the AR's western footpoint to be caused by an increase in the gas pressure gradient as lower-lying (?) denser loops reconnect with the CH open field, weakening the overlying field above the AR filament and setting the stage for eruption.

Session: Bringing Modeling and Obvservations Together

Authors: : Balmaceda, L.A.; Domingo, V.; Cabello, I.; Palacios, J.

Title: Observations of magnetic elements in the quiet Sun internetwork

Abstract: The study of the radiative properties of small-scale magnetic elements in the quiet Sun internetwork such as bright points (BPs) is of great interest to understand, among other things, their relevance in the context of solar irradiance variations. In the last few years the observation and study of BPs has undergone great progress. However, some properties such as their magnetic field strength and other physical parameters could not yet be fully determined and it is necessary to extend this study to different times during the solar cycle. The advent of Hinode data offers a great opportunity to carry out this kind of studies. Following this line of research, we present here the analysis of high-resolution images of the quiet Sun at disk center taken with the Solar Optical Telescope (SOT) on board Hinode in the CN line (388.35 nm), Ca II H (396.85 nm) and magnetograms in the Mg I line (517.27 nm). These observations are complemented with data from the Swedish 1m Solar Telescope (SST). All data sets were obtained during the Hinode/Canary Islands joint campaign in September, 2007. In particular, we investigate the morphology, contrast and magnetic properties of BPs in a first attempt to estimate their contribution to irradiance variations. The comparison with double-gaussian models for contrast and radiative flux in BP's is also presented.

Session: Solar Magnetic Activity

Authors: D. Banerjee, David Pérez-Suárez & J. G. Doyle

Title: Plumes and Inter-plumes as seen from EIS/HINODE

Abstract: Fast solar wind originates from the polar coronal hole regions. Plume structures are seen in the off-limb corona. It is not clear that if the plumes or the inter-plumes are the preferred channels for the acceleration of the fast wind. To characterize the properties of plumes and inter-plumes we use raster data obtained with the EUV Imaging Spectrometer onboard Hinode. Density sensitive line ratios of \ion{Fe}{ xiii} 203.82/202.04 and\ion{Fe}{ xii} 186.88/195.12 together with corresponding CHIANTI atomic data are used to calculate the density. Full-Widths-at-Half-Maximum and Doppler maps are obtained from the strongest\ion{Fe}{ xii} 195.12 AA spectral line. Using the line width variation of spectral lines with height, one can also try to identify the presence waves as they propagate out of the sun. The characteristic properties of these waves can also be studied while studying the variation of line widths. Some new results from EIS on HINODE on this subject will be also presented.

Session: Source of the Solar Wind/CME

Authors: Helena Becher

Title: Inversions of Stokes profiles

Abstract: We present inversions of Stokes vector profiles obtained by the Hinode SOT/SP instrument and the ground-based SOLIS VSM instrument and inverted with the publically available HAO inversion code LILIA written by Hector Socas-Navarro. This code is based on SIR (Stokes Inversion based on Response functions), which produces a height dependent atmospheric model and uses a non-linear least-square fitting technique. Both instruments use the 630.15 and 630.25 nm Fe-lines and have high temporal and spatial resolution as well as a polarimetric sensitivity approaching 10e-4. We derive the full magnetic field vector for several time series and study the dynamic properties of the magnetic field.

Session: Solar Magnetic Activity

Authors: L.R. Bellot Rubio

Title: Sunspot magnetic fields near the diffraction limit: the Hinode view (Invited Talk)

Abstract: Thanks to the Hinode satellite it is now possible to distinguish bright and dark penumbral filaments in spectropolarimetric maps of sunspots. This important achievement helps us isolate the various magnetic components of the penumbra and characterize their physical properties more reliably. Here I will describe recent results from Stokes inversions of sunspot measurements taken by Hinode/SOT. In general, the observations confirm the scenario of large (sometimes supersonic) Evershed flows associated with the more inclined and weaker fields of the penumbra. I will also identify discrepancies between our observational understanding of the penumbra and current sunspot models. The existence of serious points of disagreement calls for refined numerical simulations of sunspot structure.

Session: Sunspot Structure and Dynamics

Authors: A. Bemporad, G. Del Zanna, V. Andretta, M. Magri, G. Poletto, Y.-K. Ko

Title: An erupting filament and associated CME observed by Hinode, STEREO and SOHO

Abstract: A multi-spacecraft campaign was set up in May 2007 to observe the off-limb corona with Hinode, STEREO and SOHO instruments (Hinode HOP 7). During this campaign, a filament eruption and a coronal mass ejection (CME) occurred on May 9 from NOAA 10953 at the West limb. The filament eruption starts around 13:30 UT and results in a CME at 4°SW latitude. Remarkably, the event was observed by STEREO (EUVI and COR1) and by the Hinode/EIS and SOHO/UVCS spectrometers. We present results from all these instruments. High-cadence data from Stereo/EUVI A and B in the HeII 304 A line were used to study the 3-D expansion of the filament. A slow rising phase, during which the filament moved southward, was followed by an impulsive phase during which the filament appeared to change direction and then contribute to the westward-expanding CME as seen in STEREO/COR 1. Hinode/EIS was scanning with the 2" slit the region where the filament erupted. The EIS spectra show remarkable non-thermal broadening in lines emitted at different temperatures, in the location of the filament eruption. The CME was also observed by the SOHO/UVCS instrument: the spectrograph slit was centered at 1.7 solar radii, at a latitude of 5°SW and recorded a sudden increase in the O VI 1032-1037 A and Si XII 520 A spectral line intensities. We discuss the overall morphology of this interesting eruptive event, and provide a preliminary assessment of its temperature and density structure.

Session: Source of the Solar Wind/CME

Authors: Svetlana Berdyugina, Mägli, S., Fluri, D., Afram, N., Lites, B.

Title: 3D structure of the sunspot umbra

Abstract: We present an analysis of Hinode spectropolarimetric data of a large sunspot with a cold umbra. We applied an inversion technique to the data recorded in the 6302 A region including two Fe I lines and many TiO and CaH molecular lines. The inversions reveal a 3D structure of the dark nucleus, umbral dots, light bridge and a diffuse background in the umbra.

Session: Sunspot Structure and Dynamics

Authors: T. E. Berger, T. J. Okamoto, T. Magara, A. M. Title, T. D. Tarbell, S. Tsuneta. G. de Toma

Title: New Findings on Prominence Dynamics (Invited Talk)

Abstract: We review the Hinode/SOT observations of prominences to date with emphasis on the discoveries of several new dynamic properties including Alfven wave propagation in active region prominences, plume upflows, and bubble instabilities in quiescent prominences. In addition we note that while all active region prominences in the database exhibit horizontal thread structuring, quiescent prominences are primarily vertically structured leading to the suggestion that the magnetic topology of these two types of prominences may be fundamentally different. We compare this finding to recent models of prominence magnetic structure. We also compare the dynamics seen in Hinode/SOT prominences with recent discoveries in MLSO H-alpha movies that may show similar phenomena.

Session: Solar Magnetic Activity

Authors: R. Bhattacharyya, B. C. Low and P. Smolarkiewicz

Title: Magnetic relaxation in an incompressible viscous fluid

Abstract: We demonstrate spontaneous current sheet formation during the relaxation of a three dimensional magnetic field in a viscous, perfectly conducting incompressible magnetofluid. The current sheet manifests itself in the form of magnetic tangential discontinuity created when different parts of the fluid press each other as it relaxes to the lowest magnetic energy state. One novel feature of the numerical scheme used for this purpose is the description of the magnetic field in terms of evolving flux surfaces which are possible sites of tangential discontinuity formation. The computation follows initial global flux surfaces of simple geometry as they evolve in time to more complex forms creating magnetic tangential discontinuities in the process. This work illustrates the physics of spontaneous current sheet formation as described in the Parker theory.

Session: Flare Physics

Author: : Laura Bone

Title: Interaction and Eruption of Active Region and Quiescent Filaments in association with the Flare and CME of 19th May, 2007.

Abstract: A CME which erupted on 19th May, 2007 was accompanied by a B9.5 flare and resulted in a magnetic cloud near Earth that was registered by the STEREO-B and WIND spacecraft on 22nd May. Two independent filaments, Active Region and Quiescent, are observed in the days before the flare and eruption. Observations of the filament merger and accompanying heating are presented. Dynamic behaviour of the filament during the merger is examined. This includes heating cycles, when filament material disappears from the H alpha images and is observed in emission by XRT, that precede a final filament disappearance, heating and eruption. These stages are observed by instruments on Hinode, STEREO and TRACE. The associated B 9.5 flare, whose formation is part of the eruption, has an extreme thermal character. Possible models for the merger topology and eruption instability are discussed.

Session: Source of the Solar Wind/CME

Author: Juan Manuel Borrero

Title: Are there field-free gaps near tau=1 in sunspot penumbrae?

Abstract:
The vertical stratification of the magnetic field strength in sunspot penumbrae is investigated by means of spectropolarimetric observations at high spatial resolution from the Hinode spacecraft. We find that, in those regions where the magnetic field is more inclined and the Evershed flow is strongest (penumbral intraspines), the magnetic field can either increase or decrease with depth. A more careful analysis suggests that the magnetic field initially decreases from logtau_5 = -3 until logtau_5 = -0.7, but increases again below that. These results make it highly unlikely that regions void of magnetic fields are present at, or right below, the tau_5=1 level in the penumbra. However, they are compatible with the presence of a horizontal flux-tube-like field embedded in a magnetic atmosphere.

Session: Sunspot Structure and Dynamics

Authors: J. Buechner

Title: From DC current heating to 3D reconnection - the modes of magnetic energy conversion in the chromosphere and corona investigated by means of numerical RMHD simulations based on Hinode observations

Abstract: With its high resolution observations Hinode provides unique new opportunities to enhance our understanding of the magnetic coupling between the photosphere and the corona via the chromosphere. The non-local and non-linear character of this coupling as well as the lack of direct observations of magnetic fields in chromosphere and corona makes it necessary to use numerical simulation methods to describe the main properties of the coupling processes. Appropriate models have to take into account the complex structure of the coronal magnetic field in its relation to its photospheric sources, the inhomogeneity of the strongly structured plasma, the coupling of ions to the neutral atoms in the chromosphere and the transition between different plasma regimes in the atmosphere of the Sun. We have developed a numerical modelling approach which takes these factors into account. Our model starts with the observed photospheric magnetic field and derives the consequences of the photospheric energy input. We applied our model to heating events in the quiet solar atmosphere, observed by Hinode. We found that due to the changing plasma conditions a transition takes place between DC current heating in the lower corona to 3D magnetic reconnection in higher layers.

Session: Bringing Modeling and Obvservations Together

Authors: : Mats Carlsson, Boris Gudiksen, Viggo H. Hansteen

Title: Dynamic MHD Models of the Chromosphere and Corona (Invited Talk)

Abstract: The question of what heats the solar corona has been one of the central problems in solar physics for more than fifty years. The non-radiative flux that powers the corona has to pass through the solar chromosphere, a region where all but a few percent of the flux is converted into heat and radiation. From increasingly detailed observations it is clear that this interface between the photosphere and corona is a very complex and dynamic region and that interpretation of the observations will give vital clues to the nature of the non-radiative flux.

It is now computationally possible to treat the full convection zone-photosphere-chromosphere-corona system with some degree of physical realism. We will describe recent results of such dynamic MHD models of the solar chromosphere and corona with special emphasis on using these models to interpret high resolution observations.

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: : Rebecca Centeno

Title: Hinode's SP and Gband co-alignment

Abstract: We analyze the co-alignment between Hinode's BFI-Gband images and simultaneous SP maps with the aim of characterizing the general off-sets between them and the second order non-linear effects in SP's slit scanning mechanism. We provide calibration functions and parameters to correct for the nominal pixel scales and positioning.

Session: Past, Present, and Future Collaborative Observational/Theory Programs

Authors: : Jongchul Chae

Title: Magnetic Activity on the Sun Revealed by Hinode/SOT (Keynote Talk)

Abstract: Hinode observations have given us an unprecedented opportunity of understanding fine-scale magnetic activities on the Sun. The data produced by the Solar Optical Telescope(SOT) are particularly useful in the investigation of the interaction between magnetic field and plasma in the photosphere and chromosphere, opening the new era of observational magnetohydrodynamics (MHD). As an illustration, I would like to introduce new results and questions in three topics we have worked on. One is the determination of scale-dependent magnetic diffusivity in the photosphere, which seems to be closely related to the turbulent cascade of magnetoconvection. Another topic is the nature of magnetic reconnection in the chromosphere as manifest in the flux cancellation observed in the photosphere. Our new result is that the rates of flux cancellation determined from Hinode/SOT are much higher than those determined from SOHO/MDI. I will discuss the physical implications of this finding. Finally, I will present our finding of a pattern of horizontal flows in a quiescent prominence that consisted of a number of vertical threads. We think that this flow pattern has an important clue to solving the mystery of vertical threads and downflows along the threads in quiescent prominences.

Session: Solar Magnetic Activity

Authors: : L. Yelles Chaouche, S. Solanki, M. Cheung, A. Lagg and M. Schussler

Title: Flux emergence at the solar photosphere

Abstract: We investigate the observational signature of flux emergence in the solar photosphere obtained with 3D radiation-MHD simulations. The simulations consider the emergence of a twisted magnetic flux tube through the solar surface. We study different stages in the emergence process, starting from the early appearance of the flux tube at the solar surface. At every stage we numerically compute Stokes profiles for the two iron lines Fe I 6301.5 {\AA} and 6302.5 {\AA}. We degrade the obtained profiles in spectral and spatial dimensions to simulate observation conditions. Then, following observational practice, we apply Milne-Eddington-type inversions to the synthetic spectra in order to retrieve different atmospheric parameters. The so obtained parameters are compared with observational results obtained with Hinode's SP by Okamoto et al. 2008. We find that both observations and simulations agree on the general picture of an upwardly emerging horizontal flux tube with sub-kilogauss field strength. The simulations show that after interaction with granulations, the field is redistributed to a more vertical configuration. During this process the initially upwardly emerging flux tube, slows down and the magnetized plasma concentrates in intergranular lanes with downflowing motion. The analysis of the magnetic filed vector indicates that the magnetic flux tube was less twisted in the observations comparing to simulations.

Session: Bringing Modeling and Obvservations Together

Authors: Mark Cheung, Manfred Schuessler, Ted Tarbell, and Alan Title

Title: Solar surface emerging flux regions: a comparative study of radiative MHD modeling and Hinode SOT obserations

Abstract: We present results from numerical modeling of emerging flux regions on the solar surface. The modeling was carried out by means of 3D radiative MHD simulations of the rise of buoyant magnetic flux tubes through the convection zone and into the photosphere. Due to the strong stratification of the convection zone, the rise results in a lateral expansion of the tube into a magnetic sheet, which acts as a reservoir for small-scale flux emergence events at the scale of granulation. The interaction of the convective downflows and the rising magnetic flux undulates it to form serpentine field lines emerging into the photosphere. Observational characteristics including the pattern of emerging flux regions, the cancellation of surface flux and associated high speed downflows, the convective intensification of photospheric flux tubes, the appearance of anomalous darkenings, the formation of bright points and the possible existence of transient kilogauss horizontal fields are discussed in the context of new observations from the Hinode Solar Optical Telescope. Implications for the local helioseismology of emerging flux regions are also presented.

Session: Bringing Modeling and Obvservations Together

Authors: S. Christe, S. Krucker, and H. Hudson

Title: The Microflare Height Distribution from RHESSI

Abstract: We report on the height distribution of soft and hard X-rays from large numbers (of order 104) of microflares observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) over five years of data beginning in 2002. These events invariably occur in active regions. The excellent spectral spectral resolution of RHESSI lets us clearly distinguish the thermal (~3-10 keV) from the nonthermal (~10-20 keV) sources. The statistical analysis is similar to that of Matsushita et al. (1992) for early observations from Yohkoh. We observe the expected limb-brightening pattern of occurrence towards the limb, leading to a peak that is about 0.01 solar radii above the limb. We fit this distribution with parametrized Monte Carlo models and with simple geometrical models and report the implications for active-region structure.

Session: Flare Physics Heating

Author: : Len Culhane

Title: The Unusual Thermal Flare of 19 May 2007 – Evidence for Direct Heating in the Corona?

Abstract: Observations with Hinode EIS and XRT, RHESSI and TRACE show that the GOES B9.5 class flare had a long-lived thermal hard X-ray source with little or no evidence of impulsive behaviour in hard X-ray or radio emission. EIS in particular observed the flare plasma in some 21 spectral windows that included emission lines from He II (Log T = 4.7) to Fe XXIV (Log T = 7.2). We present observations of a range of plasma upflow velocities and non-thermal line broadening from the emission lines. The RHESSI images and spectra suggest that heating due to energetic electrons is largely absent. We examine other possible heating mechanisms that could explain the presence of plasma at temperatures ranging up to 20 MK.

Session: Flare Physics

Authors: Sanja Danilovic

Title: Investigating the origin of high speed downflows in solar magnetic features

Abstract: Hinode/SP data reveal the frequent occurrence of high speed downflows in magnetic features located in the quiet Sun. Such high-speed downflows are also seen in 3D radiation MHD simulations that, when reduced to Hinode resolution, look quite similar to the observed ones. We study the 3D structure and the evolution of the magnetic field in the 3D simulations in search of the source of these rapid downflows.

Session: Bringing Modeling and Obvservations Together

Authors: Alisdair Davey, Jonathan Cirtain, Eva Robrecht

Title: Observations of an XRT jet driving a filament eruption.

Abstract: We explore an XRT jet and a subsequent unwinding filament eruption using data from XRT, EIS and a suite of solar instruments. We surmise that the reconnection in the XRT jet leads to both material being injected into the solar wind, and down-flowing material that precipitates a filament destabilization and subsequent eruption, creating, in effect, a mini-CME. We examine the characteristics of the CME produced and compare it to other small scale CMEs.

Session: Source of the Solar Wind/CME

Authors: C.E. DeForest & D.A. Lamb

Title: Does NFI resolve the fundamental scale of flux emergence in the solar network?

Abstract: Magnetic feature tracking of MDI data has revealed that the solar network is not formed primarily by emergence events at the few-arcsecond scale; rather, most network-scale network flux concentrations appear to be formed by coalescence of many smaller elements at the subgranular scale. Comparison between simultaneous data sets from SOHO/MDI and Hinode/NFI confirms this statistical result.

We report on a similar statistical analysis of the NFI data, to determine whether NFI resolves the fundamental scale of flux emergence. Image deconvolution using the measured PSF of NFI is required to measure evolution on these smallest scales.

Session: Solar Magnetic Activity

Authors: C.E. DeForest, L. Rachmeler, & C. C. Kankelborg

Title: Fluxon modeling of solar eruptive events

Abstract: The fluxon approach to MHD modeling was developed to study the interplay of topology, reconnection, and eruptive destabilization in a controlled environment where reconnection can be controlled explicitly. Our code, FLUX, is currently the only code that can perform controlled numerical experiments on the metastable systems that give rise to CMEs, jets, and other eruptive events; it also uses under 1% as much computing power as more conventional codes. An initial result is that the Aly-Sturrock criterion may be irrelevant to real solar features. We report on recent results, the status of the code, and incorporation of photopheric magnetograms to drive semi-empirical simulations.

Session: Past, Present, and Future Collaborative Observational/Theory Programs

Authors: Saar, S., DeLuca, E.E., Farid, S.

Title: Full Sun DEM's

Abstract: We use sets of full sun multi-filter observations to study the thermal structure of different solar features. The data sets include both full resolution and 8x8 binned observations with 8 or more filter combinations. We will present DEM profiles for QS, XBP, CH and AR. The existence of high temperature plasma in the QS will be investigated.

Session: Hinode Perspectives on Coronal/Chromoshperic Heating

Authors: Farid, S., Saar, S., DeLuca E.E.

Title: Spatial, and Thermal Properties of X-Ray Bright Points

Abstract: Multi-filter full sun XRT observations are used to explore the spatial and thermal prosperities of bright points identified by an automated XBP finder. There is a tendency of XBP to be hotter with increasing size. We have also found a class of XBPs that are particularly hot.

Session: Hinode Perspectives on Coronal/Chromoshperic Heating

Author: : G. Del Zanna and S. Bradshaw

Title: Coronal loops: new insights from EIS observations.

Abstract: Multi-instrument observations of coronal loops of different active regions are presented. Hinode/EIS high-cadence observations clearly show how dynamic loops are at all temperatures. This clearly reflect the fast changes in the photospheric magnetic fields measured by SOT over a minute timescale. Despite that, persistent patterns are present. In particular, I will show that the pattern of dopplershifts and non-thermal widths in the TR-coronal lines, found for the first time in NOAA 10926 (cf. Del Zanna 2007, 2008), is actually a common feature in all active regions. This suggests that the majority of 'cool' (0.5-1 MK) loops are observed during their radiatively cooling phase. I will also discuss the complexities in measuring temperatures, densities and filling factors from the EIS spectra. Finally, I briefly discuss new atomic calculations and line identifications relevant for EIS.

Session: Perspectives on the Physics of Coronal Loops

Author: : G. Del Zanna V. Andretta, G. Poletto, Y.-K. Ko, L. Teriaca, and H. Mason

Title: Multi-instrument campaigns to observe the off-limb corona.

Abstract: Previous experience in organising multi-wavelength campaigns has clearly shown how important they are for science, despite the complexities and effort that goes into organising them. I briefly describe two campaigns I coordinated to observe the off-limb corona in 2007, and preliminary results obtained from them.

The first was a SOHO/Hinode/TRACE/STEREO/Ulysses week-long campaign during the SOHO-Ulysses quadrature in May 2007. The original aim was to measure Ne,Te, chemical abundances from the limb up to 1.7 solar radii, focussing on SOHO/CDS, Hinode/EIS, SOHO/UVCS. Various constraints somewhat limited our goal, however we were very fortunate in that an active region appeared on the Sun at the right longitude, and that a CME was observed by all instruments. The second one was a SOHO/Hinode/TRACE campaign to study the north polar coronal hole and measure the physical parameters of plume/interplume regions from the low corona to 1.7 solar radii, during the period 30 October - 4 November 2007. We obtained SOHO/CDS, SOHO/UVCS, TRACE, STEREO and Hinode observations, and during the SOHO/SUMER campaign a 1.5 days of targeted observations.

Session: Past, Present, and Future Collaborative Observational/Theory Programs

Authors: : B. De Pontieu, M. Carlsson, S. McIntosh, V. Hansteen, T. Tarbell, L. Heggland

Title: Connecting Spicules and Alfven Waves in the Chromosphere (Invited Talk)

Abstract: In the past few years, high-resolution observations with ground-based telescopes and the Broadband Filter Imager (BFI) and Narrowband Filter Imager (NFI) of the Solar Optical Telescope onboard Hinode, as well as advanced radiative MHD numerical simulations have revolutionized our view of spicules and their role in the chromosphere. We review some of these results, including the discovery of two different types of spicules with different dynamics and formation mechanisms, as well as the finding that the chromosphere is riddled with strong Alfvenic waves. We further focus on the thermal evolution and velocities of spicules by comparing Dopplergrams made in the Na D 589.6 nm, H-alpha 656.3 nm and Mg B 517.3 nm passbands and filtergrams in the Ca H 396.8 nm passband, with SUMER UV spectra from transition region lines.

This work was supported by NASA contract NNM07AA01C. The Hinode mission is operated by ISAS/JAXA, NAOJ, NASA, STFC, ESA and NSC.

Session:Hinode Perspectives on Coronal/Chromospheric Heating

Author: : Kenneth Dere

Title: The plasma filling factor of coronal bright points

Abstract: Rastered spectra of regions of the quiet Sun were recorded by the Extreme ultraviolet Imaging Spectrometer during operations with the Hinode satellite. Calibrated intensities of Fe XII lines were obtained and images of the quiet corona were constructed. From the imaged spectra, the emission measures and geometrical widths of coronal bright points were obtained. From density-sensitive line ratios, electron densities were determined. A comparison of the emission measure and bright point widths with the electron densities yielded the plasma-filling factor. The median electron density of coronal bright points is 4 $\times$ 10$^{9}$ cm$^{-3}$ at a temperature of 1.6 $\times$ 10$^6$K. The volumetric plasma filling factor of coronal bright points was found to vary from 4 $\times$ 10$^{-5}$ to 0.2 with a median value of 0.015.

Session: Perspectives on the Physics of Coronal Loops

Authors: DeRosa, Marc L. & Schrijver, Carolus J. & Barnes, Graham & Leka, K.D. & Lites, Bruce W. & Aschwanden, Markus J. & Thalmann, Julia & Valori, Gherardo & Wheatland, Michael S. & Wiegelmann, Thomas & Cheung, Mark & Conlon, Paul A. & Fuhrmann, Marcel & Inhester, Bernd & Régnier, Stéphane & Tadesse, Tilaye

Title: Nonlinear Force-Free Magnetic Field Modeling of the Solar Corona: A Critical Assessment

Abstract: Nonlinear force-free field (NLFFF) modeling promises to provide accurate representations of the structure of the magnetic field above active regions, from which estimates of physical quantities of interest (e.g., free energy and helicity) can be made. However, the suite of NLFFF algorithms have so far failed to arrive at consistent solutions when applied to cases using the highest-available-resolution vector magnetogram data from Hinode/SOT-SP. It is our view that the lack of robust results indicates an endemic problem with the NLFFF modeling process, and that this process will likely continue to fail until (1) more of the far-reaching, current-carrying connections are within the observational field of view, (2) the solution algorithms incorporate the measurement uncertainties in the vector magnetogram data, and/or (3) a better way is found to account for the Lorentz forces within the layer between the photosphere and coronal base. In light of these issues, we conclude that it remains difficult to derive useful and significant estimates of physical quantities from NLFFF models.

Session: Bringing Modeling and Obvservations Together

Authors: G. de Toma, R. Casini, A.G. de Wijn, J.T. Burkepile, B.C. Low, K.S. Balasubramaniam, & T.E. Berger

Title: Observations of Large-Scale Dynamic Bubbles in Prominences

Abstract: Prominences are very dynamic, showing continuous motions down to their smallest resolvable spatial and temporal scales. However, as macroscopic magnetic structures, they are remarkably stable during their so-called quiescent phase. We compare recent ground-based and HINODE observations of large-scalebubble-like, dynamic substructures that form within quiescent prominences and rise through the prominences without disrupting them. We discuss the implications of these new observations for hydromagnetic models of prominences.

Session: Solar Magnetic Activity

Authors: Alfred de Wijn and Daniel Müller

Title: On the relationship between magnetic field and mesogranulation

Abstract: We investigate the relation between Trees of Fragmenting Granules (TFGs; Roudier et al. 2003) and the locations of concentrated magnetic flux in internetwork areas. The former have previously been identified with mesogranulation (Roudier & Muller, 2004). While a relationship has been suggested to exist between these features (e.g., De Wijn et al. 2005, Lites et al. 2008), no direct evidence has yet been provided.

Session: Solar Magnetic Activity

Authors: Alfred de Wijn, Scott McIntosh, Bart De Pontieu

Title: Interactions between reversed granulation, p-modes, and low-lying loops

Abstract: We investigate features that are observed in Ca II H sequences from Hinode in places where reveresed granulation seems to interact with p-modes. These features appear ubiquitously in the quiet sun. They are co-spatial with reversed granulation, and display similar general properties, but have sharper edges and show fast brightness change. They also appear predominantly above wide intergranular lanes, indicating a potential connection with low-lying magnetic loops. We report on the appearence and dynamics of these features using high-resolution, high-cadence observations from Hinode, and we discuss the possible implications of p-mode interactions with low-lying magnetic loops in the chromosphere.

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: : T. Van Doorsselaere, V. M. Nakariakov, E. Verwichte, P. R. Young

Title: Waves in the solar corona: mode identification and using EIS to do seismological magnetic field measurements.

Abstract: Last year, Tomczyk et al. (2007) have conclusively proven that low amplitude (1km/s) waves are ubiquitously present in the corona. Using MHD wave theory, we demonstrate that fast magneto-acoustic kink waves reproduce the observational signatures reported by Tomczyk et al. (2007). We point out that Alfven modes take a torsional character and produce a spectral line broadening rather than a Doppler shift.

We present the results of numerical simulations of transverse velocity waves. These simulations show that the wave energy can only propagate along the magnetic field if perpendicular plasma structuring is present. As such, the discovery of low amplitude waves in the corona guided by the magnetic field constitute the seismological evidence that the corona has perpendicular density structuring.

We report the first spectroscopic detection of a kink MHD oscillation of a solar coronal structure by EIS. The detected oscillation has an amplitude of 1km/s in the Doppler shift of the FeXII 195Ĺ spectral line (1.3MK), and a period of 296s. The unique combination of EIS's spectroscopic and imaging abilities enables us to measure simultaneously the mass density and length of the oscillating loop. This enables us to measure directly the magnitude of the local magnetic ﬁeld, the fundamental coronal plasma parameter, as 39 \pm 8G, with unprecedented accuracy.

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: : Frantisek Farnik

Title: The Soft X-ray Spectrophotometer SphinX for the CORONAS-Photon Mission

Abstract: At the end of this year a new solar satellite (CORONAS-Photon) will be launched in Russia. Among the scientific payload there will be the Polish instrument SphinX developed during the project of the Polish-Russian-Czech-Italian cooperation. The instrument will observe the soft X-ray spectra with high sensitivity and moderate spectral resolution. The poster describes the instrument characteristics, its calibration, precision and measurement philosophy. The scientific objectives are also given in details.

Session: Past, Present, and Future Collaborative Observational/Theory Programs

Authors: C.E. Fischer, Alfred de Wijn, Rebecca-Centeno Elliott, Bruce Lites, C.U.Keller

Title: Analysis of high cadence HINODE SP quiet sun time series

Abstract: The HINODE SOT Spectro-polarimeter instrument can take full Stokes profiles with a high spatial and temporal resolution. This makes it possible to observe theoretically predicted mechanisms such as convective forcing and convective collapse. Filtergrams taken simultaneously in chromospheric lines give us the oppurtunity to relate the photospheric events with chromospheric behaviour of the magnetic elements. We present here a study of several time series taken with the HINODE SOT instrument.The data was recorded with the broadband filter in Ca II H, the narrowband filter in Mg I b and with the Spectro-polarimeter (SP) in dynamics mode. Thanks to the short exposure of the SP (1.6 sec) and the small field of view (30 slit positions) we can study events with a time development in the order of a minute. We identify and make a statistical analysis of events which are for example driven by convective forcing or show convective collapse.

Session: Solar Magnetic Activity

Authors: Th. Straus, B. Fleck, S.M. Jefferies, G. Cauzzi, S.W. McIntosh, K. Reardon, G. Severino, M. Steffen, T.D. Tarbell

Title: On the Role of Acoustic-gravity Waves in the Energetics of the Solar Atmosphere

Abstract: We revisit the dynamics and energetics of the solar atmosphere, using a combination of high-quality observations and 3D numerical simulations of the overshoot region of compressible convection into the stable photosphere. We discuss the contribution of acoustic-gravity waves to the energy balance of the photosphere and low chromosphere. We demonstrate the presence of propagating internal gravity waves at low frequencies (< 5mHz). Surprisingly, these waves are found to be the dominant phenomenon in the quiet middle/upper photosphere and to transport a significant amount of mechanical energy into the atmosphere outweighing the contribution of high-frequency (> 5mHz) acoustic waves by more than an order of magnitude. We compare the properties of high-frequency waves in the simulations with results of recent high cadence, high resolution Doppler velocity measurements obtained with SOT/SP and SOT/NFI on Hinode. Our results seem to be in conflict with the simple picture of upward propagating sound waves. We discuss the implications of our findings on the energy flux estimate at high-frequencies.

Session: Bringing Modeling and Obvservations Together

Authors: : Morten Franz, Rolf Schlichenmaier

Title: Spectral Analysis of Sunspot Penumbrae Observed with HINODE

Abstract: The nature of the energy transport in the penumbrae of sunspots is a controversially discussed aspect at the moment. Is it convection in magnetic field free gaps that exist in the space separating areas of strong magnetic field which is more or less static? Is it a convective flow that is channeled by magnetic flux tubes? Or is it by means of dissipative turbulent magneto-convection?

To investigate the plasma flow on a small scale we used spectropolarimetric data of sunspots at different heliocentric angles recorded by HINODE. We created maps of apparent Doppler velocities by taking advantage of the line shift of Fe 630.15 nm with respect to an averaged Fe 630.15 line core of the quiet Sun. Since we deduced the line shifts in the wing of Fe 630.15, that is, between 85 % and 95 % continuum intensity, we were able to visualize the flow pattern in the low photosphere.

In sunspot penumbrae close to disk center, the flow pattern along the line of sight, which we interpret as the vertical component of the Evershed flow, consists of a series of elongated ‘pearl chain’ like structures, extending radially through the entire center side penumbra. The up-flow appears not as a single elongated filament, but is concentrated in patches of strong up-flow separated by weaker up-flow or even down-flow. Due to projection effects the down-flow appears stronger on the limb side penumbra, but it is dislocated and spread out over a wide area in the outer penumbra. For sunspot penumbrae at large heliocentric angles these patterns are obscured by a combination of the horizontal Evershed flow and projection effects, but they are still ascertainable.

Session: Sunspot Structure and Dynamics

Authors: : Daisuke Fujimura, Saku Tsuneta

Title: Discovery of Alfven waves in the photosphere

Abstract: We present a discovery of propagating Alfven waves in the solar photosphere. We detect clear magnetic field and velocity fluctuations with amplitude of 50(G) (3.4%) and 0.17(km/s) (38%) respectively in vertical flux tubes with the@spectro-polarimeter of the Solar Optical Telescope (SOT) aboard Hinode satellite. Applying fast Fourier transform to the time profile of magnetic field strength and velocity, we found common strong peaks with period of 4-13 minutes, depending on flux tubes. We confirmed that these fluctuations are superposition of ascending and descending Alfven waves from the analysis@of the phase relationship between magnetic field strength and velocity. In@the case that ascending Alfven wave is stronger, Alfven velocity and density@at photosphere are estimated to be 4.9(km/s) and 9.0x 1017 (cm-3),@respectively, and the pointing flux is estimated to be 6.2x107@(erg/s/cm2).

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: Dali Georgobiani, Junwei Zhao, Alexander Kosovichev, David Benson, Robert Stein, Ake Nordlund

Title: Applying helioseismic techniques to realistic simulations of solar convection

Abstract: We apply various helioseismic methods, as well as local correlation tracking, to realistic large scale simulations of solar convection, and compare some of the results to the SOHO/MDI high resolution observations and to the Hinode data. Our goal is to investigate the surface and sub-surface structures and test helioseismic measurements.We calculate the k-omega and the time-distance diagrams for the simulated data and show that the results are consistent with the SOHO/MDI observations. We apply the f-mode analysis to the simulated data, calculating travel time maps for surface gravity waves; travel time differences are proportional to the horizontal flow divergence. Calculating east-west and north-south travel time differences, we obtain proxies for the horizontal velocity components.We also apply correlation tracking technique to the simulated vertical velocity and calculate horizontal velocities. We compare these results to the actual simulated velocities. Both techniques successfully recover the flow pattern of the surface velocity field. All these methods reveal similar large scale convective patterns and provide a solid initial test of helioseismic techniques.

Session: Local Helioseismology with Hinode

Authors: M. K. Georgoulis, V. S. Titov, & Z. Mikic

Title: Current-Carrying Magnetic Flux Tubes in the Solar Atmosphere: Commonplace or a Rare Occurrence?

Abstract: We attempt a fresh look on the long-standing problem of neutralized vs. non-neutralized electric current patterns in solar active regions. A rather prevailing viewpoint being that active regions include significant non-neutralized electric currents but they are current-neutralized as a whole, many original studies had suggested revisiting the problem when data of higher resolution and quality were available. We calculate the electric current patterns using two vector magnetograms from Hinode's SpectroPolarimeter; one of an eruptive, and one of a non-eruptive, active region. We find that magnetic flux emergence does not simply inject raw electric currents in the solar atmosphere. Significant non-neutralized currents tend to flow only along strong magnetic polarity inversion lines (PILs), which only exist in a small percentage of active regions. The more flux-massive a PIL, the stronger the non-neutralized currents it contains. Concluding, we attempt an interpretation of this finding.

Session: Solar Magnetic Activity

Authors: Sarah Gibson

Title: Whole Heliosphere Interval (Invited talk)

Abstract: The Whole Heliosphere Interval (WHI) is an international coordinated observing and modeling effort to characterize the three-dimensional interconnected solar-heliospheric-planetary system at solar minimum, using observations originating at the Sun during Carrington Rotation 2067: March 20 - April 16, 2008. WHI's science begins with the solar interior and extends through the heliosphere and interplanetary space out to the heliopause. WHI is a special campaign period of the International Heliophysical Year, and involves the participation of many observatories and researchers around the world. In this talk I will highlight WHI research to date, including interdisciplinary studies which trace the effects of solar structures (e.g., open/closed magnetic boundaries, fast/slow solar wind) through the heliosphere, and analyze the transport of energy (e.g., magnetic and radiative) from below the solar surface out to the Earth.

Session: Past, Present, and Future Collaborative Observational/Theory Programs

Authors: : Green, L.M., Kliem, B., Toeroek, T., van Driel-Gesztelyi, L., Attrill, G.

Title: What can soft X-ray sigmoids tell us about flux rope formation and associated eruptions?

Abstract: Soft X-ray images of the Sun have shown that some active regions contain loops, or collections of loops, which appear forward or reverse 'S' in shape. These structures are known as sigmoids and are of interest because sigmoidal active regions have a high probability of producing an eruption.

Different models have been put forward to explain the magnetic topology of sigmoids. We investigate these models by studying filament eruptions from sigmoid regions. In several cases we find a clear sign of rotation of the filament apex as it erupts which indicates a conversion of twist to writhe in a flux rope topology during this phase. However, the direction of rotation shows that the sigmoid is not contained in the flux rope. We use Hinode and Yohkoh observations to further investigate which sigmoid models are realistic and when and how the flux rope formation occurs. We find evidence for a transition from an arcade to a flux rope topology as well as evidence for a bald patch separatrix surface under a flux rope in some events.

Session: Bringing Modeling and Obvservations Together

Authors: : Paolo C. Grigis, Edward DeLuca, Leon Golub

Title: XRT observations of quiet Sun nanoflares

Abstract: We present high-cadence Hinode/XRT soft X-ray observations of the quiet Sun corona and a statistical analysis of its variability on short timescales (minutes to hours). Localized brightenings (nanoflares) are observed mostly in confined structures characterized by the presence of compact, bright, hot loops (bright points). Brighter structures are associated with stronger activity, suggesting that they are heated by the nanoflares. We explore the connection between this coronal activity (as mapped from the soft X-ray image sequences) and the underlying magnetic field structures.

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: Leon Golub, Alexander Engell, Adriaan A. van Ballegooijen, Kelly E. Korreck, and Katharine K. Reeves

Title: Modeling the Twisted Coronal Loops in AR 10938

Abstract: Hinode/XRT observations of AR 10938 on 2007 Jan 18 indicate that the coronal loops observed in this active region are not aligned with the potential field. Based on an MDI magnetogram, we construct a non-linear force-free field (NLFFF) model of the active region by injecting electric currents parallel to the potential field lines and evolving the field to a force-free state using magneto-frictional relaxation. The current distribution is adjusted such that selected model field lines fit the observed coronal loops. Although the fit is not unique, this provides an estimate of the 3D shape of the observed loops and magnetic field strength as function of position along the loops. Using this information, we construct models of temperature and density along these loops. The results are compared with XRT observations in different filters. This work is funded by the Hinode/XRT contract from NASA to SAO.

Session: Perspectives on the Physics of Coronal Loops

Author: : Mandy Hagenaar

Title: Magnetic Flux Emergence on Different Scales

Abstract: Magnetic flux emerges on the Sun on many different scales, from weak intranetwork to network concentrations and (ephemeral) active regions. Methods previously developed to recognize regions of magnetic emergence on MDI Full Disk magnetograms fail when applied to Hinode/SOT Stokes maps: the resolution is so much higher that simple bipoles on MDI are observed as collections of fragments. We present a new method for the automated detection and characterization of flux emergence on a range of scales, Our findings are compared with simulations, and we discuss the implications for our understanding of emerging flux ropes.

Session: Solar Magnetic Activity

Authors: : I. G. Hannah

Title: Combined RHESSI and Hinode Flare Observations (Invited Talk)

Abstract: Thousands of flares have been observed with RHESSI since Hinode launched in late 2006 and hundreds of these events have coverage with both spacecraft. The combination of these data sets provides powerful insights into the underlying flare physics of particle acceleration and heating. I will discuss the flare observations that have been done using both RHESSI and Hinode and possible future analysis.

Session: Flare Physics

Authors: E. P. Kontar and I. G. Hannah

Title: Regularized inversion techniques for the analysis of XRT Differential Emission Measures

Abstract: Hinode XRT provides unprecedented spatial resolution knowledge of the plasma temperature distribution resulting from heating in the solar atmosphere. However, the inference of the Differential Emission Measure DEM(T) from XRT raw data is an ill-posed inverse problem. Here, we develop and apply an enhanced regularization algorithm used in RHESSI X-ray software for this process making use of general constraints on the form of the differential emission measures. We show by simulations that this technique yields DEM(T) with considerably more information and higher quality than previous algorithms. The algorithm naturally provides signal dependent resolution of the method thus giving a clear criteria to determine whether the plasma is consistent with isothermal model.

Session: Flare Physics

Authors: : H. Hara

Title: Coronal Plasma Motions in Active Region Loops Observed with Hinode EIS

Abstract: The solar active region 10938 has been observed from the disk center to the west limb with the Hinode EUV Imaging Spectrometer. In the disk center observation, subsonic upflow motions of tens of km/s and enhanced nonthermal velocities have been found near the footpoints of the active-region loops assuming a single Gaussian approximation for the emission-line profiles. When the same part of the active region is observed near the limb, both upflows and enhanced nonthermal velocities essentially decrease. There is a strong correlation between Doppler velocity and nonthermal velocity. Significant deviations from a single Gaussian profile are found in the blue wing of the line profiles for the upflows. These suggest that there are unresolved high-speed upflows. We discuss the implications for coronal heating mechanisms.

Session: Perspectives on the Physics of Coronal Loops

Author: : Louise Harra

Title: Outflows related to flares and CMEs (Invited Talk)

Abstract: This invited review will concentrate on the latest results from Hinode regarding the response to the corona during an eruptive event. The changes in the atmosphere can be long lasting, and Hinode now allows us to observe the velocity structure in the atmosphere.

Session: Source of the Solar Wind/CME

Authors: L. Heggland, B. De Pontieu and V. H. Hansteen

Title: Observational signatures of simulated reconnection events in the solar chromosphere and transition region

Abstract: We present the results of numerical simulations of wave-induced magnetic reconnection in a model of the solar atmosphere from the photosphere to the corona. In the magnetic field geometry we study, the waves, driven by a monochromatic piston and a driver taken from Hinode observations, induce periodic reconnection of the magnetic field, and this reconnection appears to help drive long-period chromospheric jets. We produce simulated observations in several transition region and chromospheric lines, and find many similarities to the signatures of explosive events, some types of spicules and other phenomena thought to be caused by reconnection.

Session: Bringing Modeling and Obvservations Together

Authors: Hudson, H.S., Fivian, M.D., Zahid, H.J.

Title: Implications of RHESSI measurements of solar shape and faculae

Abstract: The solar aspect sensors of the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) allow us to study the precise shape of the Sun in a narrow bandpass filter at about 6700A. The measurement is analogous in some ways to Dicke's original oblateness measurements. Interpreted strictly as limb position, the individual measurements have a precision of a few milli arcsec (mas), and we have been obtaining about 100 points per second since launch in February 2002. We find the oblateness of the Sun (the difference of equatorial and polar radius) in July-September 2004 to have been 7.98+-0.14 mas, consistent with the expectation from the surface rotation rate. To obtain this result we made use of the (positive) correlation we observed between the RHESSI radius value and the brightness of the EIT 284A limb. This correlation establishes a relationship between facular brightening and apparent radius. On-disk data show that facular contrast has a maximum at intermediate values of mu and decreases again at the extreme limb. The behavior of the contrast at the extreme limb is not well understood at present, but the limb observation show that it cannot go exactly to zero. We discuss this in the context of the "hot wall" and cloud models of faculae and plage, noting that the hot wall model would predict zero contrast at the limb.

Session: Solar Magnetic Activity

Authors: Hui Tian

Title: Cool and hot components of a coronal bright point

Abstract: We performed a systematic study of the Doppler shifts and electron density measured in an EUV bright point observed simultaneously in more than 10 EUV lines with formation temperatures from log(T/K) = 4.5 to 6.3. Those parts of a BP seen in transition region and coronal lines are deŻned as its cool and hot components, respectively. We find that the transition from cool to hot occurs at a temperature around log(T/K) = 5.6+-0.1. The two components of the BP reveal a totally different orientation and Doppler-shift pattern, which might result from a twist of the associated magnetic loop system. The analysis of magnetic-field evolution and topology seems to favour a two-stage heating process, in which magnetic cancelation and separator reconnection are powering, respectively, the cool and hot components of the BP. We also found that the electron densities of both the cool and hot components of the BP are higher than those of the surrounding quiet Sun, and comparable to or smaller than active-region densities.

Session: Hinode Perspectives on Coronal/Chromoshperic Heating

Authors: Kiyoshi Ichimoto and SOT team

Title: Convective nature of the Evershed Effect Observed by SOT/Hinode

Abstract: The Evershed effect has been one of the longstanding mystery in solar physics in its nature and origin. The Solar Optical Telescope (SOT) aboard Hinode revealed the fine scale structure of the Evershed flow and its relation to the filamentary structures of the sunspot penumbra; The Evershed flow is confined in narrow channels with nearly horizontal magnetic fields embedded in deep layer of penumbral atmosphere. It is a dynamic phenomenon with the flow velocity close to the sound speed in the photosphere, and individual flow channels are associated with tiny upflow (source) at the inner end and down flow (sink) at the outer end. The penumbral bright grains are exactly correlated with the upflowing gas, thus the Evershed flow is certainly carrying the heat to maintain the penumbral brightness. SOT/Hinode also discovered the twisting appearance of penumbral filaments which may be attributed to the overturning convective motions. thus the Evershed effect may be naturally interpreted as a consequence of the convection under the strong inclined magnetic field in sunspot penumbra. We will discuss the current penumbral models, i.e., the rising flux tube model and the gappy model, in the lights of the new observations provided by Hinode.

Session: Sunspot Structure and Dynamics

Authors: Yusuke Iida, Takaaki Yokoyama and Kiyoshi Ichimoto

Title: The vector magnetic and Doppler velocity fields at the cancellation sites

Abstract: Spatial structures and time evolutions of the vector magnetic and Doppler velocity fields around the magnetic cancellatoin sites are studied by using the Hinode SOT Spectropolarimeter (SP) and Filtergrams (FG). Two senarios, i.e. the "U-loop emergence" and "Omega-loop submergence" scenarios are theoretically suggested, but it is still indefinite which of them occurs in the cancellation regions. In order to study this, the magnetic and velocity field structures at the cancellation sites are investigated. We used the data sets of the quiet sun to find relatively isolated cancellation events away from, e.g., plages or networks. Two cancellation events are studied in detail so far. >From the vector magnetic data synthesized from the SP observations, we found a horizontal field (100 - 300 Gauss) connecting the colliding opposite polarities in each of the investigated events. We also found stable red-shift downflow patches around the cancellation sites by using the Dopplergrams obtained by the FG at the NaI wavelength band. Note that the effect of the 5-minute oscillations was subtracted from the images by taking temporal averages over longer than five minutes. Interestingly, the red-shift patches are already seen in each of the positve and negative polarities even before the collision. They show an apparent motion toward the collision site during the cancellation event along with the appearance of the horizontal field. We interpret that these magnetic and velocity structures and evolutions support the submergence scenarios at the cancellation sites.

Session: Solar Magnetic Activity

Authors: S. Imada, H. Hara, T. Watanabe, A. Asai, T. Minoshima, L. K. Harra, and J. T. Mariska

Title: Non-Gaussian line profiles associated with flows in a large solar flare (Invited Talk)

Abstract: We studied the characteristics of the non-Gaussian line profile of Fe XIV in and around the flare arcade (13th Dec 2006). We found that the broad non-Gaussian line profiles associated with redshifts were observed in the flare arcade. There were two typical types of broad line profile. One was distorted line profile caused by multiple flows, and the other was symmetric line profile without any additional component. We successfully distinguished those two types by higher order statistical moments or M defined in this talk. The distorted/symmetric broad line profiles were preferentially observed in new/old flare loops, respectively. The symmetric broad line profiles can result from the turbulence. Our results may indicate that the old flare loops stores the turbulent plasma.

Session: Flare Physics

Authors: K. Ishibashi

Title: Plasma Temperature of Hot and Diffused Emission in the Quiet Sun Coronae

Abstract: High throughput and sensitivity of the Hinode/XRT allow us to detect hard X-ray plasma at much lower emissivity than the Yohkoh/SXT could. Through medium-Beryllium filter, the Hinode/XRT detected the presence of hard X-ray diffused coronal plasma (T ~ 5 -- 10MK) in the Quiet Sun state. The presence of such hot emission -- not related to any active regions -- appears to be somewhat restricted in the mid-latitude region in space, but somewhat ubiquitous in time.

A question has been raised as to whether the plasma temperatures of those diffused structures truly approach to ~10MK. With multi-filter observations by the Hinode/XRT, a crude spectroscopic analysis can be performed to identify if a copious amount of hot X-ray emission (e.g., Si XIII forming at kT ~ 0.86keV or other lines below 10AA) are present in their spectra. This presentation addresses results of such plasma diagnostics.

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: Ryohko Ishikawa and Saku Tsuneta

Title: Statistical properties of transient horizontal magnetic fields

Abstract: Following discovery of horizontal magnetic field with ASP (Lites et al 1996), and the SOLIS and GONG instruments (Harvey et al. 2007), high resolution spectro-polarimetric observations with the SOT have confirmed this finding, and extended the studies considerably (Lites et al　2008, Centeno et al. 2007, Orozco Suarez et al. 2007, Ishikawa et al. 2008, Ishikawa & Tsuneta 2008, Tsuneta et al. 2008).

We present statistical properties of the transient horizontal magnetic field (THMF). The topics to be reported include (1) size and life time distribution, (2) vertical speed of THMF, (3) locations of emergence and disappearance in terms of granular structure, (4) PDF (probability distribution function) of intrinsic magnetic field strength, filling factor, and degree of linear polarization (5) orientation of the field vector. The extensive statistical survey reveals numbers of so far unknown unique and remarkable properties of THMFs, leading us to conclude that 1) THMFs are receptive to convective motion and 2) a local dynamo processes is essentially responsible for THMFs. We also estimate the magnetic energy flux carried by THMFs based on the statistical　data and find that these magnetic energy fluxes are comparable to total chromospheric and coronal energy loss (Withbroe & Noyes 1977), implying a role of THMF for chromospheric heating and dynamism (Ishikawa and Tsuneta 2008).

Session: Solar Magnetic Activity

Author: : Aase Marit Janse

Title: Spontaneous Current Sheets: Radically different in 3D fields vs in 2D fields

Abstract: We present mathematical models to demonstrate the inevitability of current-sheet formation in a magnetic field governed by the ideal hydromagnetic induction equation, as described by the Parker theory. This process, central to the heating of the solar corona, is radically different in fully three-dimensional fields as compared with two-dimensional fields. Magnetic neutral points or separatrix flux surfaces are necessary for sheet formation in two-dimensional fields. In fully three-dimensional fields, current sheets form readily even in the complete absence of neutral points and separatrix surfaces, and, these sheets can form densely throughout the field in response to changes in the magnetic volume. This general result is established for fields that are topologically untwisted, including the first direct demonstration of sheet formation in the absence of any magnetic neutral point. Implications of this basic result for understanding the flare phenomenon will be discussed.

Session: Flare Physics

Author: : Phil Judge

Title: New Perspectives on the Chromosphere/Transition Region" (Keynote Talk)

Abstract: I will review observations and theoretical work concerning the role of the chromosphere as the lower boundary for the corona. I will highlight the need for measurements of the chromospheric magnetic field as the plasma regimes change from beta $>$ 1 to $<$ 1, using a striking observational example. I will review some of the important physical processes occurring within the partially ionized chromosphere which can greatly alter the conditions at the coronal base from those expected based only upon photospheric measurements. I will re-iterate the obvious conclusion, but one often ignored, that one must understand specific chromospheric processes if one is to have hope of addressing the nature of the supply of mass, momentum and energy into the corona.

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: Suguru Kamio, Hirohisa Hara, Tetsuya Watanabe, and Werner Curdt

Title: Outflows from the Sun (Invited Talk)

Abstract: We studied properties of coronal jet and explosive events in a polar coronal hole and their relationship with photospheric magnetic fields. Hinode/SUMER collaboration allowed us to investigate small-scale activities in the coronal hole with a broad temperature coverage. Coronal jets are classified into two categories; transient jets and stable jets associated with bright points lasting over one hour. Detailed analysis indicates that their locations coincide with localized strong magnetic fields in the photosphere, which are perpendicular to the local surface. There are also cool upflows and explosive events only identified in transition region temperatures. They preferably occurred near weak network fields which may be low-lying fields in the transition region. We summarize properties of observed events and discuss their implications for the magnetic configuration in the coronal hole.

Session: Source of the Solar Wind/CME

Authors: Ryouhei Kano

Title: Photospheric Magnetic Activities to Trigger Micro-Flares observed with the Hinode SOT and XRT.

Abstract: For understanding the coronal heating, it is important to reveal the coupling between photospheric magnetic activities and coronal transient events. Micro-flares are a good target to study the coupling, because they are smaller and simpler than flares.

In the active region 10923, no major flare happened on November 14, 2006, but many micro-flares were observed with the Hinode X-ray Telescope (XRT). We used a set of longitudinal magnetogram taken with the filtergpam of the Hinode Solar Optical Telescope (SOT). We found that most of the micro-flares were associated with magnetic activities below their footpoints. From the observation, flux emergence is the dominant source to trigger micro-flares.

Session: Hinode Perspectives on Coronal/Chromoshperic Heating

Authors: Kato, Y., Magara, T., and Shimizu, T.

Title: Radiation Transfer Analysis on Heating Mechanism of Magnetohydrodynamic Emerging Magnetic Flux Tubes

Abstract: In spite of the large number of magnetohydrodynamic (MHD) simulations of the emerging flux tube in the solar atmosphere, radiation properties of the MHD emerging flux tube have been poorly understood. This is because a heating at the footpoint of the emerging magnetic field lines is significant and the heating process accompanied with the heat conduction and the vaporation in the MHD flux tube have not been worked out yet. In this study, by using a heating model based on MHD data, we have performed three-dimensional (3-D) multi-wavelength radiation transfer calculation of the MHD emerging flux tube in order to examine our MHD models and also to identify a possible heating mechanism of the observed X-ray coronal loops. It is found that the current dissipation model are difficult for reproducing the structure of X-ray loops observed by Hinode XRT and Yohkoh SXT. This suggests that alternative modeling of heating process should be incorporated into our MHD models. We discuss some unresolved issues of heating process in the MHD emerging flux tube.

Session: Perspectives on the Physics of Coronal Loops

Authors: : Jun'ichi Kotoku(NAOJ), Toshifumi Shimizu(ISAS/JAXA), Ryousuke Imada(NAOJ), Yukio Katsukawa(NAOJ), Ryouhei Kano(NAOJ), Saku Tsuneta(NAOJ), Taro Sakao(ISAS/JAXA), Hinode team

Title: Long time observation of X-ray bright point with Hinode

Abstract: We observed quiet region for 13 hours on 10 Oct 2007 with Hinode and found X-ray bright points with magnetic canceling feature. This system consists of three magnetic poles: positive, negative, positive. West two poles showed clear magnetic cancelation feature. During the observation time, there seemed to be no strong correlation with X-ray light curve and the flux of magnetic fragments around footpoints. We report magnetic features and time evolutions of this X-ray bright point.

Session: Solar Magnetic Activity

Authors: : Y. Katsukawa, J. Jurcak, K. Ichimoto, Y. Suematsu, S. Tsuneta, T. Shimizu, T. E. Berger, R. A. Shine, T. D. Tarbell, B. W. Lites

Title: Chromospheric Activity at the Smallest Scales Obtained by Hinode (Invited Talk)

Abstract: HINODE Solar Optical Telescope (SOT) found ubiquitous occurrence of fine-scale jetlike elongated brightenings in penumbral chromospheres, which are referred to as penumbral microjets. Their very transient nature suggest that magnetic reconnection in interlaced magnetic field configuration is the most possible cause of penumbral microjets. In order to understand magnetic configuration driving penumbral microjets, we investigated relationship between penumbral microjets seen in CaII H images and photospheric magnetic fields measured by the SOT spectro-polarimeter. We found the inclination angles of penumbral microjets derived with CaII H images are roughly consistent with inclination angles of a relatively vertical background component in uncombed magnetic field configuration. In addition, we found small areas with downflows at photospheric layers that are coincident with brightenings seen in Ca II H images. The size of the downflow patches is 0.5'' or smaller. They are sporadically observed in the center-side penumbra and have different geometry from the Evershed flow. We derived, using a Stokes inversion technique with height-dependent atmospheric model, that the downflows preferentially take place in the lower photosphere. The downflow is a possible signature of the chromospheric brightenings in the penumbra and might correspond to downward outflows driven by magnetic reconnection.

Session: Solar Magnetic Activity

Authors: : R. KITAI, T. KAWATE, Y. HASHIMOTO, T. MATSUMOTO, H. WATANABE, K. OTSUJI, T. NAKAMURA, N. NISHIZUKA, K. NISHIDA, S. UENO, S. NAGATA AND K. SHIBATA

Title: Solar Plages : Chromospheric Heating and Spicular Mass Ejections

Abstract: At Hida observatory of Kyoto University, we continue to study the heating and mass ejection phenomena in the solar chromosphere with Domeless Solar Telescope (DST) and Solar Magnetic Activity Research Telescope (SMART). In this work, we will report some recent cooperative observational results with Hinode on the following topics:

(1) Plage heating and waves Analysis of a long time series of CaII K spectrograms at a plage area showed us a clear co-existence of 3- and 5-min oscillation in Doppler velocity. The phase relation between the Doppler velocity and the intensities of CaII K line showed different behavior according to the oscillatory mode. We simulated the response of the VAL model atmosphere to the input of 3-min or 5-min acoustic disturbances, in 1-D geometry. With the results of CaII K line profile synthesis by MULTI code of the disturbed atmosphere, we will discuss unsteady heating of plage chromosphere similar to the quiet chromospheric heating model proposed by Carlsson and Stein (1997).

(2) Disk spicules in and around plage regions After applying a special image processing (MADMAX) to SOT/Hinode BFI images in CaII H, we clearly identified numerous ejecting features in a plage area. Their morphological shapes of thin tapered cylinder and their dynamics strongly suggest us that they are spicules in a plage. The plage area was observed spectroscopically in Ca II H&K lines with the DST telescope, simultaneously as the SOT/Hinode BFI observation. Basic properties of these spicular features will be reported and be discussed from the view point of Type I, II classification of limb spicules ( de Pontieu et al. 2007).

Session: Hinode Perspectives on Coronal/Chromospheric Heating

Authors: I.N. Kitiashvili, L. Jacoutot, A.G. Kosovichev, N.N. Mansour, A.A. Wray

Title: Realistic Numerical Modeling of Solar Magnetoconvection and Oscillations

Abstract: We have developed 3D, compressible, non-linear radiative magnetohydrodynamics simulation to study the influence of the magnetic field of various strength and geometry on the turbulent convective cells and on the excitation mechanisms of the acoustic oscillations by calculating spectral properties of the convective motions and oscillations. The results reveal substantial changes of the granulation structure with increased magnetic field, and a frequency-dependent reduction in the oscillation power in a good agreement with Hinode observations. These simulations results explain the enhanced high-frequency acoustic emission observed at the boundaries of active region ("acoustic halo" phenomenon). This phenomenon is caused by the changes of the spatial-temporal spectrum of the turbulent convection in magnetic field, resulting in turbulent motions of smaller scales and higher frequencies than in quiet Sun regions. The results of the realistic simulations and comparison with the Hinode data provide important insight into the structure of the turbulent magnetoconvection, turbulent energy transport, and excitation mechanism of solar acoustic waves.

Session: Bringing Modeling and Obvservations Together

Authors: James A. Klimchuk

Title: Models of Coronal Loops (Keynote Talk)

Abstract: It is often said that coronal loops are the fundamental building blocks of the magnetically-closed corona. This is certainly true, especially when one realizes that the diffuse component of the corona can be thought of as a collection of indistinguishable loops. During the Skylab era, it was believed that loops are in states of quasi static equilibrium. However, more recent observations combined with numerical models have revealed that this interpretation is not correct, at least for many loops. The concept of loops as bundles of impulsively-heated strands is very appealing and solves many of the problems faced by static models, but it too faces observational challenges. Yet another idea involves the fascinating phenomenon of thermal nonequilibrium. I will review the various attempts to model coronal loops and discuss how they agree and disagree with observations, paying particular attention to the latest results from Hinode.

Session: Perspectives on the Physics of Coronal Loops

Authors: Yuan-Kuen Ko, George A. Doschek, Harry P. Warren

Title: Ultra-Hot Plasma in Active Regions Observed by the Extreme-ultraviolet Imaging Spectrometer on Hinode

Abstract: The Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft obtains high resolution spectra of the solar atmosphere in two wavelength ranges: 170 - 210 and 250 - 290 angstroms. These wavelength regions contain a wealth of emission lines covering temperature regions from the chromosphere/transition region (e.g., He II, Si VII) up to soft X-ray flare temperatures (Fe XXIII, Fe XXIV). Of particular interest for understanding coronal heating is a line of Ca XVII at 192.86 angstroms, formed near a temperature of 5 million degrees. This line is blended with lines of Fe XI and O V. However, by using a specific procedure outlined in this paper, the Ca XVII line can be extracted from the blended emission. EIS has obtained many raster observations of active regions by stepping the slit in small increments across the active region, producing monochromatic images of the active region. The Ca XVII blend has been included in many of these rasters. In this paper we discuss the procedure to extract the Ca XVII line from the blend and show examples of the 5 million degree plasma emission in several active regions. We find that the 5 million degree corona has two morphological features in these active region loops -- `fat' medium-sized loops confined in smaller regions than the 1-2 million degree corona, and diffusive emission surrounding these loops. We discuss the emission measure of the 5 million degree plasma relative to the cooler plasma in the active regions.

Session: Perspectives on the Physics of Coronal Loops

Authors: K. E. Korreck (1), G. Stenborg (2)

1. SAO 2. Interferometrics, Inc.

Title: Flows from Flaring Active Regions Observered with Hinode's XRT and STEREO

Abstract: Outflows from the Sun somehow make up the solar wind. The fast solar wind is now attributed to coronal holes, however, the source of the slow solar wind is more uncertain. Recent work has pointed to flow coming from the edges of active regions as the source of the slow solar wind. We explore outflows from Hinode's XRT as well as STEREO to understand the outflow parameters. The outflow information is used to propagate a solar wind parcel to 1AU. The ACE SWICS data is then used to compare outflows seen at these sources and then at 1AU.

Session: Source of the Solar Wind/CME

Authors: A.G. Kosovichev

Title: Recent Progress and Future Directions for Helioseismology (Invited Talk)

Abstract: Hinode/SOT observations provide unique data for high-resolution helioseismology. These data have allowed us for the first time to resolve the subsurface convective boundary layer, investigate the structure of sunspot oscillations, detect flare-generated MHD waves in the sunspot umbra, carry out multi-wavelength studies of solar oscillations, and obtain helioseismic data for probing the subsurface dynamics in near-polar regions. The future directions in helioseismology will be focused on understanding the mechanism of solar dynamo, diagnostics of emerging magnetic flux, formation and evolution of sunspot regions and their flaring activity. These tasks require development of new helioseismology methods for probing conditions in strong magnetic field regions and in the deep convection zone, including the tachocline. The new developments in helioseismology will be supported by realistic MHD simulations and based on massive data analysis from Hinode and Solar Dynamics Observatory.

Session:

Authors: Sam Krucker and R.P. Lin

Title: Coronal hard X-ray thin target bremsstrahlung emission from flare-accelerated electrons

Abstract: Coronal hard X-ray emissions provide unique information about the supra-thermal electrons closest to the site in the corona where their acceleration is believed to occur. However, the intense hard X-ray emissions from footpoints of flare loops generally make it impossible to observe faint coronal sources. Coronal hard X-ray emissions from flare-accelerated electrons are therefore best observed in partially-limb occulted flares.

Here we present X-ray observations of a partially limb-occulted solar flare taken by the X-ray telescope (XRT) onboard Hinode and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Non-thermal X-ray emission during the impulsive phase is observed to come from a coronal loop. Two minutes later at the soft X-ray peak, the non-thermal loop seen in the impulsive phase is observed in thermal soft X-ray emission. This support the standard flare model where flare-accelerated non-thermal electrons produce thin target hard X-ray emission in the flare loop and precipitate into the chromosphere heating and evaporating hot plasma that fill the flare loop. These observations provide one of the best evidence for hard X-ray thin target bremsstrahlung emission from flare-accelerated electrons in the corona.

Session: Flare Physics

Authors: : Masahito Kubo

Title: Magnetic Flux Loss and Flux Transport in a Decaying Active Region

Abstract: We estimate the temporal change of magnetic flux perpendicular to the solar surface in a decaying active region by using a time series of the spatial distribution of vector magnetic fields in the photosphere. The vector magnetic fields are derived from full spectropolarimetric measurements with the Solar Optical Telescope aboard Hinode. We compare a magnetic flux loss rate to a flux transport rate in a decaying sunspot and its surrounding moat region. The amount of magnetic flux that decreases in the sunspot and moat region is very similar to magnetic flux transported to the outer boundary of the moat region. The flux loss rates of magnetic elements with positive and negative polarities are balanced each other around the outer boundary of the moat region. These results suggest that most of the magnetic flux in the sunspot is transported to the outer boundary of the moat region as moving magnetic features, and then removed from the photosphere by flux cancellation around the outer boundary of the moat region.

Session: Sunspot Structure and Dynamics

Authors: Masahito Kubo

Title: Evolution of Vector Magnetic Fields of Dark-cored Penumbral Filaments

Abstract: We investigate temporal change of the vector magnetic field and velocity field in a dark-cored penumbral filament, using a time series of G-band images and simultaneous spectropolarimetric measurements with the Solar Optical Telescope aboard the Hinode spacecraft. Magnetic and velocity field maps with a 5.5 minute cadence are derived from the spectropolarimetric measurements with an assumption of a Milne-Eddington atmosphere. Strong Evershed flows are observed along the dark core and originate from a penumbral bright grain. The dark core having the strong Evershed flows elongates toward the umbra with the inward motion of the penumbral bright grain. The dark core has weaker and more horizontal fields than its lateral brightenings when the Evershed flows are observed. It is confirmed that Evershed flows are closely related to the formation of the weaker and more horizontal magnetic fields. The horizontal magnetic fields with the Evershed flows disappears at almost same time as the disappearance of the penumbral bright grain, but the dark core still survives for 10-20 minutes after that. During this period, the dark core gradually becomes as bright as its lateral brightenings. These results suggest that the dark core is formed by cooling of the plasma carried by the Evershed flows.

Session: Sunspot Structure and Dynamics

Authors: Andreas Lagg (1,2), Ryoko Ishikawa (1), Laura Merenda (2), Thomas Wiegelmann (2), Saku Tsuneta (1), Sami K. Solanki (2)

(1) National Astronomical Observatory of Japan (2) Max-Planck-Institute for Solar Sytem Research, Katlenburg-Lindau, Germany

Title: Internetwork horizontal magnetic fields in the quiet Sun chromosphere: results from a joint Hinode/VTT study

Abstract: We present results from a joint Hinode/VTT observing campaign performed in May 2008. Spectropolarimetric data of a quiet Sun supergranular network cell at a heliocentric angle of 56 degrees in the He 10830 line were analyzed using an inversion code involving Hanle and Zeeman effects to retrieve magnetic field strength and direction in the upper chromosphere. Simultaneously recorded Hinode SP data reveal the photospheric magnetic field topology and clearly show the presence of magnetic flux concentrations in the internetwork. The photospheric magnetic field maps are used to feed potential field extrapolations similar to the work by Schrijver and Title (2003). The extrapolated magnetic field topology is compared with the magnetic field configuration directly resulting from the He 10830 inversions. The chromospheric measurements show horizontal magnetic structures extending over a length of up to 20 Mm above the internetwork, indicative for the presence of a magnetic canopy. The photospheric magnetic flux concentrations in the internetwork are obviously not sufficiently strong to prevent the formation of a canopy at chromospheric heights.

References:
Schrijver, C. and Title, A., ApJL 597:L165–L168, 2003

Session: Past, Present, and Future Collaborative Observational/Theory Programs

Authors: Jin-Yi Lee, Katharine K. Reeves, Korreck, Kelly E., Leon Golub, K.D. Leka and Graham Barnes

Title: Evolution of magnetic properties for two active regions observed by Hinode/XRT and TRACE

Abstract: We investigate two active regions observed by the X-ray Telescope (XRT) on board Hinode and the Transition Region and Coronal Explorer (TRACE). One shows a constant brightness of the coronal loop in both XRT and TRACE observations. The other shows a brightening in the TRACE observation just after a decrease in X-ray brightness indicating the cooling of the coronal loop. The coronal magnetic topology is derived using the magnetic charge topology (MCT) model for these two active regions applied to magnetograms from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO). We discuss the results of the MCT analysis in light of the different coronal emission behavior. This work is funded by the Hinode/XRT contract through SAO, and AFOSR contract FA9550-06-C-0019.

Session: Perspectives on the Physics of Coronal Loops

Authors: Jorrit Leenaarts

Title: MULTI3D - a 3D NLTE radiative transfer code

Abstract: I will present preliminary results from the MPI parallelized radiative transfer code MULTI3D.

Session: Bringing Modeling and Obvservations Together

Authors: K.D. Leka, Ashley Crouch, Graham Barnes

Title: Minimum Energy Method for Resolving the Azimuthal Ambiguity in Hinode/SOT Vector Magnetogram Data

Abstract: WIt has been demonstrated through a series of tests using model data that minimum energy methods are the best available automated techniques to resolve the azimuthal ambiguity that is present in solar vector magnetogram data. We have developed a fast implementation of a minimum energy method that minimizes a combination of the divergence and the current density, following Metcalf (1994). The vertical variation of the field in the divergence and current density is approximated by an extrapolation of the observed boundary. We present in this poster details of application of this code to Hinode/SOT data and demonstrate its use for the Hinode community. This work was supported by funding from NASA/LWS under contract NNH05CC75C and the NWRA subcontract from SAO under NASA NNM07AB07C.

Session: Sunspot Structure and Dynamics

Authors: M. G. Linton

Title: Flare Loop Formation via Magnetic Reconnection

Abstract: Magnetic reconnection is believed to be the key driver of solar flares, and the source of post-flare loops that form below flares. I will present simulations of patchy coronal reconnection in a flare current sheet, focusing on how localized, three dimensional reconnection creates evacuated downflowing loops which form into post-flare arcades in the low corona. I will compare the results with Hinode observations of post flare arcade loops and photospheric flare ribbons.

Session: Flare Physics

Author: :Bruce Lites

Title: Is Flux Submergence and Essential Aspect of Flux Emergence?

Abstract: High resolution Hinode observations of an emerging flux region permit one to examine the detailed structure of the magnetic field vector in emerging flux regions. We find the field to have a concave-upward geometry on the smallest scales observable (0.3"), indicating the presence of U-loops at the sites of approaching and canceling opposite polarities. This structure suggests that reconnection at or below the surface is taking place, allowing the emerging flux to rid itself of the mass that drains into the local dips in the magnetic field. Supersonic down flows are often observed adjacent to, but not coincident with, the sites of canceling flux. We suggest that these are sites that drain the mass contained in the buoyantly-rising flux elements. The observations then suggest that the sub-surface reconnected O-loops descend with convective down flows, thus making flux submergence important to the larger scale flux emergence process.

Session: Solar Magnetic Activity

Authors: Yang Liu

Title: Solar Polar Field Observed by SOHO/MDI and Hinode

Abstract: Using 1-minute cadence, time-series full disk magnetograms taken by SOHO/MDI in a campaign run in 2007 March, and the vector magnetograms taken by Hinode/SOT, we have studied evolutionary characteristics of magnetic elements in solar southern pole. We present here our exploration on relationship between lifetime and flux of magnetic elements, and distribution of element lifetime at high latitude. An attempt to measure differential rotation at high latitude is also made here.

Session: Solar Magnetic Activity

Authors: D.W. Longcope, C.E. Parnell, and A.L. Haynes

Title: The number of magnetic null points in the quiet Sun corona

Abstract: The coronal magnetic field above a particular photospheric region will vanish at a certain number of points, called null points. These points can be found directly in a potential field extrapolation or their density can be estimated from Fourier spectrum of the magnetogram. The spectral estimate, which assumes that the extrapolated field is random, homogeneous and has Gaussian statistics, is found to be relatively accurate for quiet Sun magnetograms from SOHO's MDI. The majority of null points occur at low altitudes, and their distribution is dictated by high wavenumbers in the Fourier spectrum. This portion of the spectrum is significantly affected by Poisson noise, and as many as two-thirds of null points identified from a direct extrapolation can be attributed to noise. The null distribution above 1500 km is found to depend on wavelengths that are reliably measured by MDI in either its low resolution or high resolution mode. After correcting the spectrum to remove white noise and compensate for the modulation transfer function we find that a potential field extrapolated contains, on average, one magnetic null point above 1.5 Mm over every 322 square mm patch of quiet Sun. Analysis of 562 quiet Sun magnetograms spanning the two latest solar minimum shows that the null point density is relatively constant with roughly 10% day-to-day variation. At heights above 1.5 Mm, the null point density decreases approximately as the inverse cube of height. The photospheric field in the quiet Sun is well approximated as that from discrete elements with mean flux 1.0e19 Mx distributed randomly with density 0.007 per Mm. This work supported by NASA LWS

Session: Solar Magnetic Activity

Author: : Tetsuya Magara

Title: Hinode's Observational Result on the Saturation of Magnetic Helicity Injected into the Solar Atmosphere and Its Relation to the Occurrence of a Solar Flare

Abstract: We present a result on the evolution toward the onset of a solar flare, using Hinodefs observations of photospheric magnetic field. Hinode can provide the temporal development of the photospheric field as a vector quantity, which shows that magnetic shear initially developed in a flare-productive active region (AR10930), then it decreased toward the onset of an X-class flare. The magnetic helicity in this active region first increased rapidly, while it became saturated in the late phase. We explain the physical origin of these features in terms of the emergence of a magnetic flux tube into the solar atmosphere, and investigate how it relates to the occurrence of a flare. We also discuss how the magnetic helicity evolves in different types of flares.

Session: Flare Physics

Authors: Sara Martin, Olga Panasenco, and Yashar Agah (Helio Research La Crescenta, CA, USA) Oddbjorn Engvold and Yong Lin, (Institute for Theoretical Astronphysics, Univeristy of Oslo,Norway)

Title: Relating Prominences Observed from Hinode to Known 3-D Structures of Filaments

Abstract: The 3-dimensional structure of the vast majority of prominences (filaments) consist of two interrelated magnetic and plasma structures: (1) extremely narrow, ribbon-like spines confined to curved planes parallel to polarity reversal boundaries in the photosphere and (2) barbs that have one end merged and parallel with the spine and the other gradually deviating sideways from the spine and curving downward to their roots in the chromosphere/photosphere. Both spines and barbs consist of similar fine, parallel or nearly parallel, field-aligned threads of continuously flowing plasma. To relate these structures of filaments seen against the disk to prominence observations above the limb from Hinode, as well as to prominence observations from the ground, is not always a simple task; one must take into consideration the relative visibility of the threads due principally to: (1) their number, plasma density and geometry in the spines and barbs in the various categories of prominences and (2) the column density as seen from various viewing angles, (3) spectral line observed and (4) relative instrument exposure times. Additionally, there are prominences and parts of prominences observed H alpha that have no counterpart in filaments observed in H alpha against the disk. However, a first step in relating limb and disk observations is to map well-observed prominences in three dimensions from observing and tracking the mass motions of their field-aligned threads and groups of unresolved threads from different perspectives afforded as prominences (filaments) transit the solar disk due to solar rotation. A prime example of the disk transit of a large filament is one with visible threads in its spine and very tall barbs as it was observed at Helio Research over an 18-day interval from the first appearance of its top at the east limb until it reached the west limb. This example, along with observations from the Swedish Solar Telescope and other ground and space-based observatories, are used to illustrate how various prominence structures observed from Hinode can be related to the substructures of prominences, i.e., spines and barbs, observed and not observed, in different categories prominences and seen from different viewing angles.

Session: Solar Magnetic Activity

Authors: John T. Mariska

Title: Doppler Shift Oscillations Observed with the EUV Imaging Spectrometer on Hinode

Abstract: Damped Doppler shift oscillations have been observed in emission lines from ions formed at flare temperatures with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on SOHO and the Bragg Crystal Spectrometer on Yohkoh. Recently, they have also been detected in lines formed at coronal temperatures observed with the EUV Imaging Spectrometer (EIS) on Hinode. I report on additional observations of Doppler shift oscillations in an active region observed in 2007 August. These observations include density-sensitive emission lines from Fe XII and Fe XIII. The oscillations observed with EIS generally have a much lower amplitude than those observed with earlier instruments. This is probably the result of the perturbation that initiates the oscillations being less energetic than the events that produce oscillations in much hotter emission lines. EIS is capable of detecting coronal velocity fluctuations with amplitudes of less than 0.5 km/s with short integration times in strong coronal lines, potentially allowing access to a much richer range of coronal oscillatory phenomena than has been available with earlier instruments.

Session: Perspectives on the Physics of Coronal Loops

Authors: : Cristina Chifor, Alphonse C. Sterling, Helen E. Mason, Ronald L. Moore, Peter R. Young

Title: Evidence for Tether-cutting Leading to a Filament-associated Eruption Observed by Hinode

Abstract: We present Hinode observations of the onset of a solar eruption involving a filament ejection on 2007 May 20. Results from Hinode/SOT, Hinode/XRT and Hinode/EIS have been analysed together with supporting observations from Stereo/SECCHI/EUVI and SoHO/MDI. We observed a converging motion between two opposite polarity sunspots which form the primary magnetic polarity inversion line, along which sits the filament material before eruption. The eruption onset is associated with positive emerging flux canceling repeatedly in a negative polarity region north of the sunspots. We discuss the filament eruption and small scale transient brightenings observed in the onset region prior to eruption. We derive plasma properties from the Hinode/EIS observations. We conclude that the array of observations is consistent with the pre-eruption sheared-core magnetic arcade being gradually destabilised by evolutionary tether-cutting flux cancelation that was driven by converging photospheric flows.

Session: Solar Magnetic Activity

Authors: Satoshi Masuda (STEL, Nagoya University)

Title: Construction of Hinode/XRT flare catalogue

Abstract: In the Yohkoh era, 'The Yohkoh HXT/SXT Flare Catalogue' was created (Sato et al. 2006). It was published as a printed book and is also open at the homepage of Yohkoh/HXT (http://gedas.stelab.nagoya-u.acjp/HXT/). It includes a lot of information, i.e., time, location, GOES time profile, SXT image, HXT 4-bands images, and so on. It was very useful to analyze solar flares statistically and to search events which have some characteristics.

For Hinode, we have just started creating such a catalogue. Since the sun has been quiet for these two years, Hinode have not detected a large number of events. The solar activity will increase in the near future. So it is a good time to start maintaining a flare catalogue. The pointing of Hinode changes more often than that of Yohkoh and the field of view is generally smaller than Yohkoh (HXT always covered the whole sun). The catalogue will be very helpful for researchers to know if some particular event was observed with Hinode or not. Based on the GOES flare list, at first we are checking if XRT observed the flare-occurring region during the flare period. We report the current situation.

Session: Flare Physics

Authors: James McCaughey, Iain Hannah, Kathy Reeves, Paolo Grigis, and Edward DeLuca

Title: The Neupert effect in microflares with Hinode/XRT and RHESSI

Abstract: The Neupert effect, in which the integrated hard X-ray light curve resembles the soft X-ray light curve, is often attributed to flare-accelerated particles heating and evaporating material into hot coronal loops. The Neupert effect has been observed more commonly in larger flares, although it remains unclear whether it is actually less common in microflares or rather is more difficult to detect due to the shorter duration and less intense emissions of microflares. RHESSI provides good temporal resolution of nonthermal hard X-ray emissions and some thermal soft X-ray emissions, while Hinode/XRT provides sensitive, high-resolution imagery of soft X-ray thermal emissions. We use this complementary approach to examine 74 microflares in November and December 2006 with light curves from both XRT and RHESSI. We are investigating the correlation between the presence of an observed Neupert effect and other spectral and morphological characteristics of the microflares. Further research will also aim to better constrain instrumental effects in order to clarify the degree to which the presence or absence of the Neupert effect in microflares can be reliably determined using XRT and RHESSI.

Session: Flare Physics

Authors: David E. McKenzie

Title: Solar Flare Physics in the Hinode Era (Keynote Talk)

Abstract: Hinode's manifest of instrumentation was conceived to investigate the magnetic connections through the photosphere, lower atmosphere, and corona. The complementarity of the instruments is indeed useful, as demonstrated in numerous flares and eruptions in just the first two years of operation. I will review some of the findings from Hinode's observations of flares to date.

It is true, of course, that Hinode's capabilities have evolved since launch. These changes cause the planning of observations to be more complex, and the analysis to be less straightforward; but they do not diminish Hinode's ability to produce important observations of solar flares. On the contrary, Hinode is poised to make truly surprising discoveries. I will explain why this is so, and why we should look forward to the challenge of the coming activity cycle.

Session: Flare Physics

Authors: Scott W. McIntosh

Title: The Inconvenient Truth About Coronal Dimmings

Abstract: We investigate Hinode multi-wavelength high resolution spectro-polarimetric, spectral and broadband images that span the deep photosphere into the corona over the course of a coronal dimming that took place in December 2006. These observations reinforce the belief that coronal dimmings, or transient coronal holes as they are also known, as they are indeed the locations of open magnetic flux in the corona resulting from the launch of a CME. We will see that, as open magnetic regions, they must act just as coronal holes do, only for a considerably shorter span of time - as temporary sources of the fast solar wind. An inescapable question therefore arises - what impact does this source of plasma momentum have on the propagation and in-flight characteristics of the CME that initiates to coronal dimming in the first place?

Session: Source of the Solar Wind/CME

Authors: Scott W. McIntosh, Bart De Pontieu

Title: Connecting Dynamic Phenomena with SOHO/SUMER and Hinode/SOT

Abstract: We will explore the connection of dynamic structure in the chromosphere and transition region using observations from the WHI: Quiet Sun Characterization program of April 2008. In particular, we will study the multi-thermal spectral appearance of spicules in these regions and establish their common magnetic roots.

Session: Hinode Perspectives on Coronal/Chromoshperic Heating

Author: : Ryan Milligan

Title: Velocity Characteristics of Evaporating Plasma Using Hinode/EIS.

Abstract: Chromospheric evaporation due to nonthermal electrons is commonly believed to be responsible for much of the EUV and X-ray emission observed during solar flares. Observationally this process has been investigated by detecting blueshifts of a single, high-temperature emission line such as the Ca XIX line from Yohkoh/BCS or Fe XIX from SOHO/CDS. With the launch of Hinode, the EUV Imaging Spectrometer (EIS) now offers the opportunity to diagnose this fundamental process over a multitude of high-temperature emission lines, at high spatial, spectral and temporal resolution. The work presented here focuses on how plasma velocities at loop footpoints vary as a function of temperature during the impulsive phase of a C-class flare and possible implications for the standard chromospheric evaporation model.

Session: Flare Physics

Author: : Ryan Milligan

Title: A High-Temperature Microflare Observed With RHESSI and Hinode

Abstract: In this study, data from RHESSI and Hinode are combined to investigate the origin of an unusually high-temperature of 15 MK observed during a B-class event. The absence of any detectable hard X-ray emission coupled with weak blueshifted emission lines suggests that this was a result of direct heating in the corona, as opposed to chromospheric evaporation due to nonthermal electrons. These findings are in agreement with a recent 0D hydrodynamical simulation of microflare plasmas (Klimchuk et al. 2008) which found that a higher continuum temperature can be attained whenever less energy is used to accelerate electrons out of the thermal distribution. In addition, unusual redshifts in the 2 MK Fe XV line were observed cospatial with one of the flare ribbons during the rise phase of the event. As downward flows of such high temperature plasma are not predicted by any known flare model, some possible explanations will be suggested.

Session: Flare Physics

Authors: Urmila Mitra-Kraev, Michael J. Thompson, Alexander G. Kosovichev

Title: Observations of the Sun's Meridional Flow (Invited Talk)

Abstract: The meridional flow is a key ingredient of some solar dynamo models, and may play a crucial role in the 11-year activity cycle of the Sun. The flow is poleward close to the solar surface and must, by mass conservation, turn equatorward deeper down in the convection zone. Helioseismic observations can be used to reveal the flow pattern and its variations. I will give an overview over past observations, and present recent new results on solar cycle-dependent variations of the meridional flow.

Session: Local Helioseismology with Hinode

Authors: Ron Moore

Title: Jet-Front Speed and the Origin of Jets in Polar Coronal Holes

Abstract: The area-average strength of the open magnetic field in the polar coronal holes can be estimated from the radial component of the magnetic field measured by Ulysses in the solar wind, the fraction of the solar sphere covered by the polar coronal holes, and the fraction of the heliosphere filled by the fast solar wind from the polar coronal holes. For the present minimum phase of the solar cycle, the estimated strength is ~ 10 G. Using this strength for the ambient open field in the standard reconnection model for jets in coronal holes, we obtain for any given jet-front speed a lower bound on the initial temperature of the expanding jet-front plasma, and an upper bound on the ambient plasma density at the reconnection site. These two bounds indicate the following. For jet-front speeds ~ 1000 km/s, (1) the reconnection site has to be in the low corona or upper transition region (ne < 10^9 cm^-3), not in the lower transition region or chromosphere, (2) the jet-front plasma is initially heated to T >~ 10^7 K, and (3) hence a compact X-ray flare is produced at the base of the jet. For jet-front speeds <~ 100 km/s, (1) the jet can be produced by reconnection in the lower transition region (~10^9 < ne <~ 10^10 cm^-3) or upper chromosphere (~10^10 < ne <~ 10^12 cm^-3), (2) the initial temperature of the jet-front plasma can be less than 10^6 K, and (3) hence some EUV and H-alpha jet-type macrospicules may be produced with no detectable X-ray emission.

This work is funded by NASA’s Science Mission Directorate through the Heliophysics Guess Investigators Program and the Hinode Mission Operations and Data Analysis Program.

Session: Solar Magnetic Activity

Authors: F. Moreno-Insertis

Title: X-Ray jets in coronal holes: numerical simulation and Hinode observations.

Abstract: Observations with the XRT and EIS instruments onboard Hinode show the appearance of a large number of X-Ray jets in coronal holes, in some cases simultaneously with the emergence of magnetic flux from below the photosphere. We have carried out three-dimensional numerical experiments of the reconnection and jet-launching processes that result from the emergence of magnetic flux from the solar interior into an atmosphere with open field lines, mimicking the situation in a coronal hole. In the experiment, the values of density and magnetic field in the corona are close to those expected in a coronal hole. We combine the results of the 3D numerical simulations with data from the Hinode detectors and show the results of theory and observation to be in excellent agreement.

Session: Bringing Modeling and Observations Together

Authors: Kaori Nagashima, Takashi Sekii, Alexander G. Kosovichev, Junwei Zhao, Theodore D. Tarbell, Saku Tsuneta

Title: Travel-time analyses of an emerging-flux region

Abstract: We report on travel-time analyses of a newly-formed plage region, exploiting high-resolution data provided by Hinode/SOT.

Hinode observed an emerging-flux region (to be NOAA AR 10975) close to the disc centre for 12 hours on 23 November 2007. The SOT observation was in Ca II H line and in Fe I 557.6nm line (Lande g=0); we can use both chromospheric intensity oscillation data and 'non-magnetic' photospheric Dopplergrams for our analyses. The Dopplergrams are not affected by magnetic field and, therefore, are useful in exploring magnetic structure. By cross-correlating oscillation signals, we have detected travel-time anomaly in the plage region. We are currently scrutinising the travel-time measurement method and trying to interpret the anomaly in terms of subsurface structure of this growing active region.

Session: Local Helioseismology with Hinode

Authors: Shin'ichi Nagata

Title: Convective Instability and formation of solar magnetic flux tubes

Abstract: We show the observational evidence for the formation of s

Second Hinode Science Meeting Beyond Discovery – Toward Understanding

29 September- 3 October 2008 Boulder, Colorado USA

Abstracts

Second Hinode Science Meeting
Beyond Discovery – Toward Understanding

29 September- 3 October 2008
Boulder, Colorado USA