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Astron. Astrophys. 354, 636-644 (2000)


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Calibration of [FORMULA] Pegasi system

P. Morel, Ch. Morel, J. Provost and G. Berthomieu

Département Cassini, UMR CNRS 6529, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice CEDEX 4, France

Received 12 July 1999 / Accepted 13 December 1999

Abstract

Recent observations provide determinations of individual masses, chemical composition and metallicity of the components of the spectroscopic and interferometric binary [FORMULA] Peg (Boden et al. 1999). Using updated physics, to calibrate the system, we have computed using the stellar evolutionary code CESAM (Morel 1997), evolutionary sequences of stellar models with the masses of [FORMULA] Peg A [FORMULA] and [FORMULA] Peg B [FORMULA] (Boden et al. loc. cit.) and with different values of the mixing-length parameter [FORMULA], the helium Y and the heavy element Z initial mass fraction with the constraint of the observed metallicity. Adopting effective temperatures and luminosities, as derived from observations with the bolometric corrections, and the empirical scale of temperatures of Alonso et al. (1995, 1996), we find [FORMULA], [FORMULA], [FORMULA], [FORMULA]. The evolution time, including pre-main sequence, is found within [FORMULA]. The calibrated models of [FORMULA] Peg. A and B are non homogeneous zero age main sequence stars with the evolutionary time [FORMULA] My. Due to the large uncertainties of their determinations, the values derived for the mixing-length parameters are smaller than the solar one but however marginally compatible with it. Our results ought to be improved as soon as a more accurate value of the magnitude difference in the V filter will be available. Detailed spectroscopic analysis for both components looks practicable, so it is urgently needed.

Key words: stars: binaries: spectroscopic – stars: binaries: visual – stars: fundamental parameters – stars: individual: Peg

Send offprint requests to: P. Morel

Correspondence to: Pierre.Morel@obs-nice.fr

© European Southern Observatory (ESO) 2000

Online publication: February 9, 2000

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