Variability and stellar pulsation incidence in Am/Fm stars using TESS and Gaia data

TL;DR

This study analyzes the variability and pulsation incidence in 1276 Am/Fm stars using TESS and Gaia data, revealing diverse pulsational behaviors and their relation to stellar evolution and mixing processes.

Contribution

It provides the first comprehensive analysis of pulsation characteristics in a large sample of Am/Fm stars using space-based data, highlighting the diversity of pulsational types and their evolutionary implications.

Findings

51% of stars show no variability

25% are pulsating Am/Fm or { ho} Puppis stars

54% of pulsators are { m delta} Scuti type

Abstract

Aims. We aim to study chemically peculiar Am and Fm stars, distinguished by their unique abundance patterns, which are crucial for studying mixing processes in intermediate-mass stars. These stars provide a window into the atomic diffusion in their stellar envelopes, the evolution-dependent changes in mixing, and the resulting effects on pulsation mechanisms. Methods. This study examines the pulsation characteristics of the Am/Fm star group. Our analysis encompasses 1276 stars (available as catalogues on GitHub), utilising data from TESS and Gaia and focusing on stars from the Renson catalogue. Results. In our sample, 51% (649 stars) display no variability, thus categorised as constant stars. Among the remaining, 25% (318 stars) are pulsating Am/Fm and {\rho} Puppis stars, including 20% (261 stars) that are exclusively Am/Fm stars. Additionally, 17% (210 stars) show variability indicative of binarity and/or rotational modulation and 7% (93 stars) are eclipsing binaries. Of the pulsating stars, 10% (32 stars) are {\gamma} Doradus type, 54% (172 stars) {\delta} Scuti type, and 36% (114 stars) are hybrids, underlining a diverse pulsational behaviour of Am/Fm stars. Conclusions. Our findings indicate that pulsating stars predominantly occupy positions near the red edge of the classical instability strip, allowing us to ascertain the incidence of pulsations in this stellar population.