Speaker
Description
Differential rotation is a key driver of magnetic activity and dynamo processes in the Sun and other stars, especially as they differ across the solar layers, but also in active regions. We aim to accurately quantify the velocity at which round $\alpha$-spots traverse the solar disk as a function of their latitude, and compare these rates to those of the quiet Sun and other sunspot types. We then aim to extend this work to other stars and investigate how differential rotation affects the modulation of stellar light curves by introducing a generalized stellar differential rotation law. This is achieved by tracking 105 manually identified $\alpha$-sunspots in the 6173~\AA continuum observed by the Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory (SDO). This dataset, which represents over a decade of data allows us to derive a differential rotation law for $\alpha$-sunspots, which falls in between the rotation rate of quiet Sun and younger, and more complex sunspots. We extend this analysis to other stars by introducing a scaling law based on the rigid rotation rates of these stars. This scaling law is implemented into the Stellar Activity Grid for Exoplanets (SAGE) code to illustrate how differential rotation alters the photometric modulation of active stars. Our findings emphasize the necessity of considering differential rotation effects when modeling stellar activity and exoplanet transit signatures.
