Revisiting bright delta Scuti stars and their period-luminosity relation with TESS and Gaia DR3

TL;DR

This study uses TESS and Gaia DR3 data to analyze delta Scuti stars, confirming their period-luminosity relation, identifying non-pulsators, and revealing new high-frequency delta Scuti stars with overtone sequences.

Contribution

It provides a comprehensive catalog of delta Scuti stars with revised periods and distances, clarifies the period-luminosity relation, and demonstrates the utility of this relation for star classification.

Findings

62 stars are not delta Scuti pulsators, mostly binary variables.

Most delta Scuti stars lie on a fundamental mode ridge in the period-luminosity diagram.

The period-density relation for Kepler delta Scuti stars is tightly constrained with Q=0.0315 days.

Abstract

We have used NASA's TESS mission to study catalogued delta Scuti stars. We examined TESS light curves for 434 stars, including many for which few previous observations exist. We found that 62 are not delta Scuti pulsators, with most instead showing variability from binarity. For the 372 delta Scuti stars, we provide a catalogue of the period and amplitude of the dominant pulsation mode. Using Gaia DR3 parallaxes, we place the stars in the period-luminosity diagram and confirm previous findings that most stars lie on a ridge that corresponds to pulsation in the fundamental radial mode, and that many others fall on a second ridge that is a factor two shorter in period. This second ridge is seen more clearly than before, thanks to the revised periods and distances. We demonstrate the value of the period-luminosity diagram in distinguishing delta Scuti stars from short-period RR Lyrae stars, and we find several new examples of high-frequency delta Scuti stars with regular sequences of overtone modes, including XX Pyx and 29 Cyg. Finally, we revisit the sample of delta Scuti stars observed by Kepler and show that they follow a tight period-density relation, with a pulsation constant for the fundamental mode of Q = 0.0315 d.