TESS photometry and CAOS spectroscopy of six eclipsing binaries with Am components

¹ INAF–Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
e-mail: giovanni.catanzaro@inaf.it
² Università degli Studi di Catania, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Via Androne 81, 95124 Catania, Italy

Received: 24 January 2024
Accepted: 24 February 2024

Abstract

In this paper, we present the results of a comprehensive study of six eclipsing binaries whose components are confirmed or suspected Am stars. By combining long-term, high-resolution Catania Astrophysical Observatory Spectropolarimeter (CAOS) spectroscopy and TESS photometry, we have been able to accurately obtain the orbital parameters of each system as well as the atmospheric parameters of its components. We performed an in-depth chemical analysis and provided chemical abundances of C, O, Na, Mg, Si, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Y, Zr, and Ba. From the solution of the light and radial curves, we have determined the masses, radii, and temperatures with a good degree of accuracy. We observe apsidal motion in the eccentric system HD 216429, in which the Rossiter-McLaughlin effect is also noted. We inferred the age of our targets by fitting isochrones on the HR diagram and find that both components in each system are properly described with the same isochrone, which reinforces our results. Furthermore, dynamical and evolutionary masses, independently obtained, show an excellent agreement. According to the out-of-eclipse variability shown in their TESS light curves and their position on the Hertzsprung-Russell diagram, we claim that the stars HD 42954 (as δ Sct type) and HD 151604 (γ Dor) have a pulsating nature. Based on the chemical analysis, we corroborate that four of the systems studied here are formed by Am stars, while in the remaining ones (HD 126031 and HD 216429) only the primary component exhibits a peculiar composition. Additionally, the age distribution found in Am stars supports their suitability as age tracers in stellar populations.