Short Term Variability of Evolved Massive Stars with TESS

Trevor Z. Dorn-Wallenstein, Emily M. Levesque, James R. A. Davenport

Published 2019-01-28Version 1

We present the first results from a study of TESS Sector 1 and 2 light curves for seven evolved massive stars in the LMC: five yellow supergiants (YSGs) and two luminous blue variables (LBVs), including S Doradus. We find coherent short-timescale variability in both LBVs and three of the YSGs. One of the YSGs, HD 269953, displays drastically different variability from its fellows, which may indicate nonradial pulsations. While the field surrounding HD 269953 is quite crowded, it is the brightest star in the region, and has infrared colors indicating it is dusty. We suggest HD 269953 may be in a post-red supergiant evolutionary phase. We find a signal with a period of $\sim5$ days for the LBV HD 269582. The periodogram of S Doradus shows a complicated structure, with peaks below frequencies of 1.5 cycles per day. We analyze the noise characteristics of all seven light curves, and find a red noise component in all of them. However, the power law slope of the red noise and the timescale over which coherent structures arise changes from star to star. Our results highlight the potential for studying evolved massive stars with TESS.