Asteroseismological constraints on the coolest GW Vir variable star PG 1159-typePG 0122 200 - AstrophysicsReportar como inadecuado

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Abstract: We present an asteroseismological study on PG 0122+200, the coolest knownpulsating PG1159 GW Vir star. Our results are based on an augmented set ofthe full PG1159 evolutionary models recently presented by Miller Bertolami andAlthaus 2006. We perform extensive computations of adiabatic g-mode pulsationperiods on PG1159 evolutionary models with stellar masses ranging from 0.530 to0.741 Msun. We derive a stellar mass of 0.626 Msun from a comparison betweenthe observed period spacing and the computed asymptotic period spacing, and astellar mass of 0.567 Msun by comparing the observed period spacing with theaverage of the computed period spacing. We also find, on the basis of aperiod-fit procedure, an asteroseismological model representative of PG0122+200 which is able to reproduce the observed period pattern with an averageof the period differences of 0.88 s. The model has an effective temperature of81500 K, a stellar mass of 0.556 Msun, a surface gravity log g= 7.65, a stellarluminosity and radius of logL-Lsun= 1.14 and logR-Rsun= -1.73,respectively, and a He-rich envelope thickness of Menv= 0.019 Msun. We derive aseismic distance of about 614 pc and a parallax of about 1.6 mas. The resultsof the period-fit analysis carried out in this work suggest that theasteroseismological mass of PG 0122+200 could be 6-20 % lower than thoughthitherto and in closer agreement to within 5 % with the spectroscopic mass.This result suggests that a reasonable consistency between the stellar massvalues obtained from spectroscopy and asteroseismology can be expected whendetailed PG1159 evolutionary models are considered.

Autor: A. H. Córsico, M. M. Miller Bertolami, L. G. Althaus, G. Vauclair, K. Werner


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