Doppler imaging of active young stars

Abstract

This thesis investigates the activity of three young solar analogues, R58, LQ Lup, and RX J0850.1-7554, using Doppler imaging, as a way to investigate the early history of solar activity by proxy. The spot distributions of the targeted stars have been mapped and differential rotation measurements obtained from the drift of spot features over the course of the observations. A large polar spot is present on all targets examined within this thesis, as well as the simultaneous presence of mid and low latitude features. Comparison of differential rotation results for R58 and LQ Lup to previous work suggests these stars can undergo changes in differential rotation over time. Furthermore, a differential rotation measurement for RX J0850.1-7554 suggests this star is the first known example of a G-type star with solid body rotation. Overall, the results presented suggest the young Sun was a star with a major polar spot feature and some smaller spots at lower latitudes, and most likely possessed a fundamentally different dynamo to today.s Sun.