CFHT UM2019 - Presentation Details

Abstract Details

Title: Surprising activity of A-type stars revealed by Kepler: are magnetic fields the culprit?

Presenter: James Sikora


A recent analysis of photometry obtained using the Kepler spacecraft has revealed the highly unexpected result that approximately 40% of main sequence A-type stars exhibit periodic variability that may be attributable to starspots. This is surprising in light of the fact that such activity is normally associated with the presence of magnetic fields, which are rare amongst stars much more massive than the Sun. Furthermore, a significant number of the Kepler A-type stars exhibit unusual signals in their periodograms, which have been speculatively attributed to a high frequency of hot Jupiters orbiting these stars. We have recently completed a spectroscopic survey of a subsample of the stars found to be exhibiting both of these unexpected properties. This survey is designed to test two specific hypotheses related to these discoveries including if spotted A-type stars are substantially more common than previously believed. We will summarize our findings and discuss our ongoing efforts to understand the origins of the discoveries.