Precise Evolutionary Asteroseismology of High-Amplitude {\delta} Scuti Star AE Ursae Majoris

TL;DR

This paper demonstrates how precise asteroseismology of the high-amplitude { extdelta} Scuti star AE Ursae Majoris can test stellar evolution theory at a single-star level, especially regarding its post-main-sequence stage.

Contribution

It introduces a framework for using period variations in pulsating stars to test stellar evolution models with unprecedented precision from a single star.

Findings

AE Ursae Majoris is in the post-main-sequence stage.

Observed period variation matches evolutionary predictions.

Framework can be applied to other pulsating stars.

Abstract

Stellar structure and evolution theory is one of the basis in modern astronomy. Stellar inner structures and their evolutionary states can be precisely tested by asteroseismology, since the inner information is brought to the stellar surface by the global oscillating waves and becomes observable. For stellar evolutionary speed (i.e. how long time scale does a star stay at a special evolution phase?), because of the insurmountable gap between the time scales of the evolutionary history of human civilization and a star, it can only be roughly tested by ensemble of stars in different evolutionary stages in most cases, and all the snapshots of these stars make up our global view of stellar evolution. The effect of stellar evolution on the structure and the corresponding global size of a pulsating star will lead to tiny period variations of its pulsation modes, which are the most valuable indicators of its evolutionary state and can be used to test the stellar evolution theory by a single star rather than ensemble of stars. Here, we report a High-Amplitude $\delta$ Scuti star AE Ursae Majoris, who locates in the post main-sequence (MS) evolutionary stage and its observed linear period variation rate can be practically ascribed to its evolutionary effect. The result tests the stellar evolution theory from the pre-MS to post-MS with an unprecedented precision by a single star, and the framework can be extended to other type of pulsating stars to perform precise evolutionary asteroseismology, which aims to test the current stellar evolution theory in different evolutionary stages, discover the discrepancies between the theory and observations, and ultimately build a complete and precise stellar evolution theory to backtrack the history of each of these stars.