An Investigation into the Variability of Luminous Blue Variable Stars with TESS

TL;DR

This study analyzes the variability of 37 Luminous Blue Variable stars using TESS data, revealing no correlation between their photometric Fourier parameters and stellar properties, suggesting they are similar to supergiant alpha Cygni variables.

Contribution

First comprehensive Fourier analysis of LBV light curves from TESS, comparing variability characteristics with stellar parameters across different galaxies.

Findings

No correlation between Fourier parameters and stellar properties.

LBVs may be an extension of alpha Cygni variables.

Photometric variability does not distinguish LBVs from other supergiants.

Abstract

Luminous Blue Variables (LBVs) are enigmatic, evolved, massive stars. Their variability has been observed to be episodic with large eruptions, along with variations on time-scales of days to decades. We have extracted light curves of 37 LBVs from the first four years of the TESS mission. These light curves provide two years of photometric time-series for stars in the LMC, with several months of data for Galactic or SMC targets. We analyze the Fourier properties of the stellar light curves to determine their characteristic frequencies and red noise amplitudes, comparing them to mass-loss parameters through H$\alpha$ strength, and in the case of the LMC stars, $B-V$ color and luminosity as estimated by their apparent $g$-magnitudes. We confirm the absence of correlation between any of the Fourier parameters and stellar parameters, implying that there is no trend in how these stars vary as measured with these photometric data, which may point towards these stars being an extension to the supergiant $\alpha$ Cygni variables and not a unique class of object with regards to their short-term variations.