Core properties of alpha Cen A using asteroseismology

TL;DR

This study uses long-term asteroseismic observations of alpha Centauri A to refine models of its internal structure, particularly its core, by analyzing frequency data and rotational splittings.

Contribution

It provides new asteroseismic constraints and improved frequency measurements, enhancing understanding of alpha Centauri A's core and limiting core overshooting in models.

Findings

44 detected frequencies consistent with previous studies

14 frequencies show possible rotational splittings

Derived new large and small frequency separations

Abstract

A set of long and nearly continuous observations of alpha Centauri A should allow us to derive an accurate set of asteroseismic constraints to compare to models, and make inferences on the internal structure of our closest stellar neighbour. We intend to improve the knowledge of the interior of alpha Centauri A by determining the nature of its core. We combined the radial velocity time series obtained in May 2001 with three spectrographs in Chile and Australia: CORALIE, UVES, and UCLES. The resulting combined time series has a length of 12.45 days and contains over 10,000 data points and allows to greatly reduce the daily alias peaks in the power spectral window. We detected 44 frequencies that are in good overall agreement with previous studies, and found that 14 of these show possible rotational splittings. New values for the large and small separations have been derived. A comparison with stellar models indicates that the asteroseismic constraints determined in this study allows us to set an upper limit to the amount of convective-core overshooting needed to model stars of mass and metallicity similar to those of alpha Cen A.