Halo Photometry and Asteroseismology for 98 of the Brightest Stars Observed by TESS

TL;DR

This study develops a halo photometry method to extract light curves from the brightest TESS stars, enabling asteroseismic analysis and discovery of new stellar variability in 98 stars, with data publicly available.

Contribution

We adapted halo photometry for TESS to analyze the brightest stars, detecting oscillations and variability, and linking these stars to future and ongoing observations.

Findings

Detected oscillations in 5 stars for the first time

Derived stellar masses using asteroseismic parameters

Identified new variable stars and binary signatures

Abstract

The Transiting Exoplanet Survey Satellite (TESS) mission has facilitated studies of asteroseismology, eclipsing binaries, and transits in many stars. However, the brightest stars saturate TESS, yet they are the most amenable to photon-hungry high-resolution studies and have long observational histories. In this work, we adapted the halo photometry used in $K$2 to extract light curves from the unsaturated halo pixels of the star's point spread function. We used this method to extract light curves for 98 of the brightest stars observed by TESS in Sectors 1-93. These bright stars include 15 red giants, five $\delta$ Scuti variables, eight stochastic low-frequency variables, eight eclipsing binaries, and 46 other variables. We measured $\nu_{\rm max}$ for 13 red giants using pyMON and $\Delta\nu$ for one of them, $\beta$ Gem (Pollux). For five of them, this represents the first time that oscillations were detected. We derived their stellar masses using the measured $\nu_{\rm max}$ and previous interferometric and radiometric angular diameters. We also discovered $\delta$ Scuti and $\gamma$ Doradus variability in $\alpha$ Cep, possible asteroseismic binary signatures in $\epsilon$ Car, and a new eclipsing binary, $\gamma$ And. Furthermore, we identified 18 stars in our sample that will be observed by the future PLAnetary Transits and Oscillations of stars (PLATO) mission, and 69 stars that have Stellar Observations Network Group (SONG) observations, including some simultaneous with TESS. The light curves are publicly available on the Mikulski Archive for Space Telescopes.