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

¹ DTU Space, Technical University of Denmark, Elektrovej 327, Kgs. Lyngby 2800, Denmark
e-mail: antoci@space.dtu.dk
² Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
³ Centre for Astrophysics, University of Southern Queensland, Toowoomba, Qld 4350, Australia
⁴ Instytut Astronomiczny, Uniwersytet Wrocławski, Kopernika 11, 51-622 Wrocław, Poland

Received: 22 December 2023
Accepted: 19 August 2024

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 and Fm star group. Our analysis encompasses 1276 stars (available as catalogues on GitHub), utilising data from TESS and Gaia and focussing on stars from the Renson catalogue.

Results. In our sample, 51% of stars (649) display no variability, and are thus categorised as constant stars. Among those that remain, 25% (318 stars) are pulsating Am, Fm, and ρ Puppis stars, including 20% (261 stars) that are exclusively Am and Fm stars. Additionally, 17% of stars (210) show variability indicative of binarity and/or rotational modulation and 7% (93 stars) are eclipsing binaries. Of the pulsating stars, 10% (32 stars) are γ Doradus type, 54% (172 stars) δ Scuti type, and 36% (114 stars) are hybrids, underlining a diverse pulsational behaviour of Am and 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.