Solar Transients and Space Weather (STSW)
Science Highlights
Ubiquitous Outflow in Coronal Holes has Deep Roots
McIntosh et al. (2010) build upon recent spectroscopic investigations of the roots of the solar wind exploring multi-wavelength observations of a large equatorial coronal hole (ECH) with the instruments on the Solar Dynamics Observatory (SDO) taken on August 23, 2010.
The ECH observed was the source of a persistent 650 km/s solar wind observed by ACE. A clear feature of this ECH, like its polar counterparts, is the ubiquitous appearance of persistent small high-speed ejecta visible at a range of temperatures from emission formed at ~100,000K (He II 304Å) to ~1MK (Fe IX 171Å) throughout the ECH with the Atmospheric Imaging Assembly (AIA) across temperature wherever the polarity of the local magnetic field is of the same sign as the coronal hole net polarization as observed the Helioseismic and Magnetic Imager (HMI).
In regions of stronger magnetic field throughout the ECH the same jets exhibit emission from a plasma of ~2MK at their base. In a followup to recent spectroscopic efforts, we investigate the properties of these jets, applying space-time analysis and a novel algorithm designed to track motions in coronal imaging datasets to recover phase and angular information about the jets. While preliminary, the results of the latter suggest that the apparent speed (~75km/s) of the ejecta is consistent across temperatures from the chromosphere to corona in the stronger magnetic field regions the propagation angles are consistent with those inferred from the Milne-Eddington inversion of HMI Stokes polarization measurements.
The rooting of these ejecta in cooler chromospheric material and the consistent magnitude of the velocities is consistent with the emerging picture of an explosive and relentless mass transport through the chromosphere and low transition region in the form of dynamic spicules.