Bibcode
Aparicio, A.; Bertelli, G.; Chiosi, C.; Garcia-Pelayo, J. M.
Bibliographical reference
Astronomy and Astrophysics (ISSN 0004-6361), vol. 240, no. 2, Dec. 1990, p. 262-288. Research supported by ASI, Ministero dell'Universita e della Ricerca Scientifica e Tecnologica, and Research and Education Council of Andalucia.
Advertised on:
12
1990
Citations
73
Refereed citations
66
Description
In this paper we present the Johnson-Cousins UBVR CCD photometry of the
stars in King 2, an old open cluster towards the galactic anticenter. We
have obtained the colour- magnitude diagram, the colour excess, the
reddening, an estimate of the metallicity, and the distance modulus. The
comparison of the observational colour- magnitude diagram with the
theoretical simulations based on stellar models with convective
overshoot shows that a major revision of the model structure is
required. To this aim, we explore the possibility that the formulation
of convective overshoot for stars in the mass range 1 to
2Msun ought to be different from the one currently in use.
The point of major uncertainty that we see to affect the stars in this
domain is whether or not convective overshoot may erode the gradient in
molecular weight in the regions surrounding the convective core. We find
that models, in which this is not allowed to occur, better fit the
overall morphology of the colour- magnitude diagram of King 2. In
addition to this, analyzing the width of the main sequence band we
suggest that a significant fraction of the stars are members of binary
systems, and evaluate the range spanned by their mass ratios. Finally,
we derive the luminosity function and the mass function for the main
sequence stars of the cluster.