The Changing Lightcurve of the Double-Mode RR Lyrae Variable Star V338 Boo

TL;DR

This paper analyzes the lightcurve of the double-mode RR Lyrae star V338 Boo, revealing amplitude changes in pulsation modes over 54 days, which could provide insights into stellar pulsation mechanisms.

Contribution

It presents the first detailed analysis of amplitude variations in both fundamental and overtone modes of V338 Boo using TESS data, highlighting complex pulsation behavior.

Findings

Fundamental mode amplitude varies over 54 days.

Overtone mode shows smaller amplitude changes.

Harmonics and mode combinations exhibit unusual behavior.

Abstract

We present an analysis of the lightcurve extracted from Transiting Exoplanet Survey Satellite Full Frame Images of the double-mode RR Lyrae V338 Boo. We find that the fundamental mode pulsation is changing in amplitude across the 54 days of observations. The first overtone mode pulsation also changes, but on a much smaller scale. Harmonics and combinations of the primary pulsation modes also exhibit unusual behavior. Possible connections with other changes in RR Lyrae pulsations are discussed, but a full understanding of the cause of the changes seen in V338 Boo should shed light on some of the most difficult and unanswered questions in stellar pulsation theory, and astrophysics more generally.