Starspots on the active young solar-type star AH Lep

Starspots on the active young solar-type star AH Lep

Young solar-type stars inform us about the early evolution of objects that form a major component of the stellar population of our galaxy.

Single active young solar-type stars close to the Sun’s mass also provide us with proxies for the Sun’s early history, its activity and underlying magnetic dynamo.

The active young solar-type star AH Lep provides a convenient target to image its magnetic activity in detail.

AH Lep is of particular interest because of its relatively modest rotation rate (v sin i = 28 km s-1) compared with other previously studied active stars; in other words, this star represents the opportunity to study the effects of rotation on the dynamo of young solar-type stars.

This thesis investigates the starspot features and magnetic field of AH Lep using the techniques of Doppler and Zeeman Doppler Imaging, resulting in a tomographic map of the star and magnetic field detections.

In contrast to the large polar spot features of more rapidly rotating active solar-type stars, mid-latitude starspots predominate on AH Lep. At the time of observation at least, AH Lep displayed little in the way of a polar spot and instead showed large spot features more reminiscent of the Sun today than the polar spot dominated appearance of rapid and ultrarapid rotators. Total spot coverage (3.3%) is not small but is significantly less than that of rapid rotators.

The magnetic field of AH Lep was detected in a number of observations and a tentative magnetic map was constructed. More observations under the most favourable conditions are needed to investigate more fully the magnetic topology of the star.