HAO 2010 PROFILES IN SCIENCE: Dr. Savita Mathur

Contact

303-497-2178
savita@ucar.edu

Dr. Savita Mathur is a Post Doc I in the High Altitude Observatory of NCAR. Her research interests are in helio- and asteroseismology. This includes the study of the dynamics and the structure of the solar core through gravity modes. She is currently working on the data analysis of the Kepler mission to study the oscillations of solar-like stars and red giants, and is involved in the development of the Asteroseismic Modelling Portal. Other interests include effect of flares on acoustic modes, stellar activity, instrumentation, solar modelling, and inversion techniques.

Publication:

(1) The first discovery of a stellar magnetic cycle using asteroseismic data of the CoRoT mission

Abstract:

The magnetic activity cycle of the Sun has been studied during many years. We know that this 11-year cycle manifests itself with sunspots or particle ejections that increase during the maximum of the activity cycle. However, we still don't completely understand the underlying mechanisms that govern these phenomena. The study of the activity cycles of other stars can bring us more constraints and allow us to get a broader understanding of these cycles. Work by HAO scientists in collaboration with French and Spanish scientists shows the first discovery a magnetic activity cycle in a star observed by the CoRoT satellite using seismology. They studied the temporal variation of the amplitude and frequency of the acoustic modes of the star over a period of 420 days (with a gap of 240 days). The anti-correlated variation of these two parameters is similar to what we observe in the Sun. For this star, which is 34% larger than the Sun and that rotates with a period of 3.4 days, they obtain a lower limit of 120 days for the magnetic cycle. A survey has also started to observe this star in Ca H and K lines showing that this star is an active star. The observation of a short cycle is a very interesting result having in mind the Kepler mission. If such short cycles are not so uncommon, it should be possible to observe magnetic activity cycle during the 3.5 years of observations by the mission.

Team: Savita Mathur (HAO/NCAR), R.A. Garcia (CEA Saclay, France),
D. Salabert (IAC Tenerife, Spain), J. Ballot (LATT, France), C. Regulo (IAC Tenerife, Spain), T. Metcalfe (HAO/NCAR), A. Baglin (LESIA, France)

(top panel) Light curve of HD49933 obtained with CoRoT. (second panel) Temporal  evolution of the starspots proxy. (third panel) Maximum amplitude per  radial mode versus time. (bottom panel) Temporal evolution of the frequency shifts
Figure: (top panel) Light curve of HD49933 obtained with CoRoT. (second panel) Temporal evolution of the starspots proxy. (third panel) Maximum amplitude per radial mode versus time. (bottom panel) Temporal evolution of the frequency shifts.