New seismic analysis of the exoplanet-host star Mu Arae

TL;DR

This study uses a new asteroseismic method and updated parallax data to precisely model the star Mu Arae, revealing its internal structure, high helium content, and key stellar parameters.

Contribution

Introduces a novel asteroseismic analysis approach combined with updated parallax data to accurately determine Mu Arae's properties and internal structure.

Findings

Mu Arae has a mass and radius with about 1% uncertainty.

The star has a high helium abundance around Y=0.3.

Precise estimates of the star's age, mass, and radius were obtained.

Abstract

We present detailed modelling of the exoplanet-host star Mu Arae, using a new method for the asteroseismic analysis, and taking into account the new value recently derived for the Hipparcos parallax. The aim is to obtain precise parameters for this star and its internal structure, including constraints on the core overshooting. We computed new stellar models in a wider range than Bazot et al. (2005), with various chemical compositions ([Fe/H] and Y), with or without overshooting at the edge of the core. We computed their adiabatic oscillation frequencies and compared them to the seismic observations. For each set of chemical parameters, we kept the model which represented the best fit to the echelle diagram. Then, by comparing the effective temperatures, gravities and luminosities of these models with the spectroscopic error boxes, we were able to derive precise parameters for this star. First we find that all the models which correctly fit the echelle diagram have the same mass and radius, with an uncertainty of the order of one percent. Second, the final comparison with spectroscopic observations leads to the conclusion that besides its high metallicity, Mu Arae has a high helium abundance of the order of Y=0.3. Knowing this allows finding precise values for all the other parameters, mass, radius and age.