Differential Rotation In Sun Like Stars From Surface Variability And Asteroseismology

Differential Rotation in Sun-like Stars from Surface Variability and Asteroseismology

In his PhD dissertation Martin Bo Nielsen performs observational studies of rotation in stars like the Sun. The interior rotation in stars is thought to be one of the driving mechanisms of stellar magnetic activity, but until now this mechanism was unconstrained by observational data. NASA’s Kepler space mission provides high-precision observations of Sun-like stars which allow rotation to be inferred using two independent methods: asteroseismology measures the rotation of the stellar interior, while the brightness variability caused by features on the stellar surface trace the rotation of its outermost layers. By combining these two techniques Martin Bo Nielsen was able to place upper limits on the variation of rotation with depth in five Sun-like stars. These results suggest that the interior of other Sun-like stars also rotate in much the same way as our own Sun.

Differential Rotation in Sun-like Stars from Surface Variability and Asteroseismology

Thanks to helioseismology we know the internal rotation of the Sun as a function of radius and latitude. The presence of a shear at the base of the solar convection zone is thought to play a key role in the generation of magnetic fields. So far however, the internal rotation profiles of stars other than the Sun are unknown, and placing constraints on models of rotation and magnetic dynamos is therefore difficult.. The NASA Kepler mission has provided high-quality photometric data that can be used to study the rotation of stars with two different techniques; asteroseismology and surface acti...

Asteroseismology in the Kepler Era