Modelling the components of binaries in the Hyades: the dependence of the mixing-length parameter on stellar mass |
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Authors: | M Yldz K Yakut H Bak A Noels |
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Institution: | Ege University, Department of Astronomy and Space Sciences, Bornova, 35100 ?zmir, Turkey;Institute of Astronomy, Catholic University of Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium;Department of Physics, Faculty of Arts and Sciences, Çanakkale Onsekiz Mart University, 17100 Çanakkale, Turkey;Institut d'Astrophysique et Géophysique, Universitéde Liège, Allée du 6 Aôut, B-4000 Liège, Belgium |
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Abstract: | 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. The fitting formula for this relationship can be given as α= 9.19( M /M⊙? 0.74)0.053? 6.65 , which is valid for stellar masses greater than 0.77 M⊙ . 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 θ2 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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Keywords: | stars: abundances binaries: eclipsing stars: evolution stars: interiors open clusters and associations: individual: Hyades |
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