Constraining fundamental stellar parameters using seismology. Application to α Centauri AB
Abstract
We apply the LevenbergMarquardt minimization algorithm to seismic and classical observables of the αCen binary system in order to derive the fundamental parameters of αCenA+B, and to analyze the dependence of these parameters on the chosen observables, on their uncertainty, and on the physics used in stellar modelling. We show that while the fundamental stellar parameters do not depend on the treatment of convection adopted (Mixing Length Theory  MLT  or “Full Spectrum of Turbulence”  FST), the age of the system depends on the inclusion of gravitational settling, and is deeply biased by the small frequency separation of component B. We try to answer the question of the universality of the mixing length parameter, and we find a statistically reliable dependence of the αparameter on the HR diagram location (with a trend similar to the predictions based on 2D simulations). We propose the frequency separation ratios as better observables to determine the fundamental stellar parameters, and to use the large frequency separation and frequencies to extract information about the stellar structure. The effects of diffusion and equation of state on the oscillation frequencies are also studied, but present seismic data do not allow their determination.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 October 2005
 DOI:
 10.1051/00046361:20052988
 arXiv:
 arXiv:astroph/0505537
 Bibcode:
 2005A&A...441..615M
 Keywords:

 stars: oscillations;
 stars: interiors;
 stars: fundamental parameters;
 stars: individual: α Cen;
 Astrophysics
 EPrint:
 15 pages, 8 figures, accepted by A&