Impact of the new solar abundances on the calibration of the PMS binary system RS Cha

TL;DR

This study demonstrates that stellar evolution models using the new AGS05 solar mixture can accurately reproduce the observed properties of the pre-main sequence binary system RS Cha, aligning with recent solar abundance revisions.

Contribution

It introduces stellar models based on the AGS05 solar mixture that successfully match RS Cha's observational data, improving previous calibrations with the GN93 mixture.

Findings

Models with AGS05 mixture fit RS Cha observations

Initial helium content estimated at Y~0.255

System age determined to be approximately 9.13 Myr

Abstract

Context: In a recent work, we tried to obtain a calibration of the two components of the pre-main sequence binary system RS Cha by means of theoretical stellar models. We found that the only way to reproduce the observational parameters of RS Cha with standard stellar models is to decrease the initial abundances of carbon and nitrogen derived from the GN93 solar mixture of heavy elements by a few tenths of dex. Aims: In this work, we aim to reproduce the observational properties of the RS Cha stars with stellar evolution models based on the new AGS05 solar mixture recently derived from a three-dimensional solar model atmosphere. The AGS05 mixture is depleted in carbon, nitrogen and oxygen with respect to the GN93 mixture. Methods: We calculated new stellar models of the RS Cha components using the AGS05 mixture and appropriate opacity tables. We sought models that simultaneously satisfy the observations of the two components (masses, radii, luminosities, effective temperatures and metallicity). Results: We find that it is possible to reproduce the observational data of the RS Cha stars with AGS05 models based on standard input physics. From these models, the initial helium content of the system is Y~0.255 and its age is ~9.13 +- 0.12 Myr.