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Monday 04 Apr 2016Seminar: The magnetic characteristics of cool dwarfs

Victor See - University of St Andrews

Physics, 4th floor 14:30-15:30

Low mass stars with outer convective zones are known to host strong magnetic fields at their surfaces. These fields induce stellar activity, drive angular momentum- & mass-loss and affect exoplanetary habitability. Their characterisation is therefore an important step to understanding a wide range of stellar phenomenon. Zeeman-Doppler imaging is a powerful tool that can map the strength and geometry of the large-scale magnetic fields of these stars. It is also possible to study the evolution of stellar magnetic fields via repeated observations of individual targets. Currently, we have magnetic maps for ~100 stars. A number of these stars have shown global polarity reversals similar to those the Sun undergoes every ~11 years.

In this talk, I will discuss how the magnetic characteristics of cool dwarfs vary as a function of fundamental parameters of the star. I will demonstrate that the stellar mass and rotation period are both important parameters that determine the magnetic geometry of a star. These trends give insight into the underlying dynamo mechanisms responsible for generating stellar magnetic fields. I will then go onto discuss what we can learn about stellar activity cycles from Zeeman-Doppler imaging.

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