Internal rotation and buoyancy travel time of 60 gamma Doradus stars from uninterrupted TESS light curves spanning 352 days

TL;DR

This study analyzes 60 gamma Doradus stars using TESS light curves to identify pulsation modes and measure internal rotation and buoyancy travel time, providing insights into stellar internal structure with high precision.

Contribution

It introduces a method to determine internal rotation and buoyancy travel time for gamma Doradus stars using 1-year TESS data, achieving comparable precision to longer Kepler observations.

Findings

Successfully identified modes and measured internal rotation and buoyancy travel time for 60 stars.

Achieved measurement precisions of 0.03 d^{-1} for rotation and 400 seconds for buoyancy travel time.

Demonstrated that 1-year TESS data can provide valuable constraints on stellar internal structure.

Abstract

Context. Gamma Doradus (hereafter $\gamma$~Dor) stars are gravity-mode pulsators whose periods carry information about the internal structure of the star. These periods are especially sensitive to the internal rotation and chemical mixing, two processes that are currently not well constrained in the theory of stellar evolution. Aims. We aim to identify the pulsation modes and deduce the internal rotation and buoyancy travel time for 106 $\gamma$ Dor stars observed by the Transiting Exoplanet Survey Satellite (TESS) mission in its southern continuous viewing zone (hereafter S-CVZ). We rely on 140 previously detected period-spacing patterns, that is, series of (near-)consecutive pulsation mode periods. Methods. We used the asymptotic expression to compute gravity-mode frequencies for ranges of the rotation rate and buoyancy travel time that cover the physical range in $\gamma$~Dor stars. Those frequencies were fitted to the observed period-spacing patterns by minimising a custom cost function. The effects of rotation were evaluated using the traditional approximation of rotation, using the stellar pulsation code GYRE. Results. We obtained the pulsation mode identification, internal rotation and buoyancy travel time for 60 TESS $\gamma$~Dor stars. For the remaining 46 targets, the detected patterns are either too short or contained too many missing modes for unambiguous mode identification, and longer light curves are required. For the successfully analysed stars, we found that period-spacing patterns from 1-yr long TESS light curves can constrain the internal rotation and buoyancy travel time to a precision of $\rm 0.03~d^{-1}$ and 400s, respectively, which is about half as precise as literature results based on 4-yr Kepler light curves of $\gamma$~Dor stars.