2000ApJ...531..503G -
Astrophys. J., 531, 503-520 (2000/March-1)
alpha Centauri AB.
GUENTHER D.B. and DEMARQUE P.
Abstract (from CDS):
Detailed models of α Centauri A and B based on the Hipparcos, Yale, and Söderhjelm parallaxes are compared. The consequences of the uncertainty in mass, luminosity, surface temperature, and composition on the structure and the p-mode pulsation spectrum of the models are presented. All of the models were constructed using the most current stellar structure physics available to us, including helium and heavy-element diffusion, OPAL (Lawrence Livermore Opacity Library) equation of state, and OPAL and Alexander opacities. Self-consistent models of α Cen A and B that satisfy the observational constraints have an initial helium mass fraction YZAMS≃0.28. The age of the system depends critically on whether or not α Cen A has a convective core. If it does (our best model), then α Cen AB is ∼7.6 Gyr old, and if it does not, then the binary system is ∼6.8 Gyr old. Both ages and YZAMS are accurate to ±∼10% owing to observational uncertainties. The Galactic enrichment parameter (ΔY/ΔZ) for our best model pair is less than 1. Pulsation analyses of our best models yield an average large and small spacing of 101±3 µHz and 4.6±0.4 µHz, respectively, for α Cen A, and 173±6 µHz and 15±1 µHz for α Cen B. Some methodologies that use p-mode frequency observations to constrain the system further are outlined. We include a simple test to determine whether or not α Cen A has a convective core and introduce a method to use the small frequency spacing to determine the age of system, overcoming the limitation that it is also sensitive to composition.
Abstract Copyright:
∼
Journal keyword(s):
Stars: Binaries: Visual - Stars: Fundamental Parameters - Stars: Individual: Constellation Name: α Centauri - Stars: Interiors - Stars: Oscillations
Simbad objects:
3
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2000ApJ...531..503G and select 'bookmark this link' or equivalent in the popup menu