$\delta$ Scuti pulsations in the bright Pleiades eclipsing binary HD 23642

TL;DR

This paper reports the discovery of delta Scuti pulsations in the secondary star of the bright Pleiades eclipsing binary HD 23642 using TESS data, providing insights into stellar rotation, inclination, and system properties.

Contribution

It is the first detailed analysis of pulsations in HD 23642, combining TESS photometry, spectroscopy, and stellar models to characterize the system's physical and evolutionary properties.

Findings

Detected 46 pulsation frequencies consistent with delta Scuti stars.

Found rotational splitting indicating the star's rotation period matches the orbital period.

Determined the system's age as approximately 170 million years.

Abstract

We announce the discovery of pulsations in HD 23642, the only bright eclipsing system in the Pleiades, based on light curves from the Transiting Exoplanet Survey Satellite (TESS). We measure 46 pulsation frequencies and attribute them to delta Scuti pulsations in the secondary component. We find four l=1 doublets, three of which have frequency splittings consistent with the rotation rate of the star. The dipole mode amplitude ratios are consistent with a high stellar inclination angle and the stellar rotation period agrees with the orbital period. Together, these suggest that the spin axis of the secondary is aligned with the orbital axis. We also determine precise effective temperatures and a spectroscopic light ratio, and use the latter to determine the physical properties of the system alongside the TESS data and published radial velocities. We measure a distance to the system in agreement with the Gaia parallax, and an age of 170 +/- 20 Myr based on a comparison to theoretical stellar evolutionary models.