Cool Stars 14 - Submitted Abstract # 75
This version created on 05 October 2006

Models for internal stuctures of components of Hyades binaries:  the
dependence of the mixing-length parameter on stellar mass


Mutlu Yildiz, Ege University

We present our findings based on a detailed analysis of the binaries
of the Hyades, in which the masses of the components are well known.
We fit the models of the components of a binary system to observations
so as to give the observed total V and B-V of that system and the
observed slope of the main sequence in the corresponding parts.
According to our findings, there is a very definite relationship
between the mixing-length parameter and the stellar mass.  While no
strict information is gathered for the chemical composition of the
cluster, as a result of degeneracy in the colour-magnitude diagram, by
adopting Z= 0.033 and using models for the components of 70  Tau and
theta2 Tau we find the hydrogen abundance to be X= 0.676 and the age
to be 670  Myr.  If we assume that Z= 0.024, then X= 0.718 and the age
is 720  Myr.  Our findings concerning the mixing-length parameter are
valid for both sets of the solution.  For both components of the
active binary system V818 Tau, the differences between radii of the
models with Z= 0.024 and the observed radii are only about 4 per cent.
More generally, the effective temperatures of the models of low-mass
stars in the binary systems studied are in good agreement with those
determined by spectroscopic methods.

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