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Astron. Astrophys. 318, 783-790 (1997)

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1. Introduction

The double-lined PMS spectroscopic binaries are extremely useful tools to test the relative mass and age calibrations of theoretical evolutionary models. In fact, if theoretical masses can be determined for each component of such binaries, then theoretical mass ratios can be obtained and compared with the accurate dynamical mass ratios provided by these binaries. Furthermore, the assumption of coeval formation of the binary components can be used to constrain the theoretical mass-age calibrations even more (e.g. Mathieu 1994). On the other hand, the dynamical results obtained from the observation of such binaries provide lower mass limits for each component. Although these mass limits are generally too small to constrain the theoretical models in a relevant way, in some cases, however, their values are large enough to provide useful constraints to stellar models. As we will show later, this is precisely the case for the PMS double-lined spectroscopic binary NTTS 162814-2427, making this binary particularly suitable for testing purposes (see also Mathieu et al. 1989, hereafter MWM).

In the present work we make use of the most recent observational data available for the binary NTTS 162814-2427 and the hypothesis of coeval formation of its components as a test to sequences of PMS stellar models computed with a new hydrodynamic evolutionary code. In order to estimate the uncertainties on the mass and age determinations we computed models with different physical inputs concerning the low- and high-temperature opacities, the EOS and the treatment of convection. The method used for the comparison between theoretical and observational results also allows to estimate the uncertainties on the mass-age determinations due to the uncertainties in the effective temperature and luminosity of each component.

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© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998