TESS photometry of extreme helium stars PV Tel and V821 Cen

TL;DR

This study presents TESS space-based photometry of two extreme helium stars, PV Tel and V821 Cen, revealing their variability patterns and providing new insights into their irregular light curves.

Contribution

First space-based photometric analysis of V821 Cen, confirming its variability and characterizing the irregular light curves of both stars.

Findings

V821 Cen is variable for the first time.

Both stars show irregular, non-periodic light curves.

TESS data confirms previously reported variability in PV Tel.

Abstract

PV Tel variables are extreme helium (EHe) stars known to be intrinsic light and velocity variable on characteristic timescales 0.1 - 2 d. With two exceptions, they are best described as irregular. Light curves have invariably been obtained from single-site terrestrial observatories. We present TESS observations of two bright EHe stars, Popper's star (V821 Cen) and Thackeray's star (PV Tel). PV Tel is variable on timescales previously reported. V821 Cen is proven to be variable for the first time. Neither light curve shows any evidence of underlying regularity. Implications are considered.