Bibcode
Martinez Roger, C.; Paez, E.; Castellani, V.; Straniero, O.
Referencia bibliográfica
Astronomy and Astrophysics 290, 62-68 (1994)
Fecha de publicación:
10
1994
Número de citas
13
Número de citas referidas
12
Descripción
We report the results of a CCD investigation of stars in a selected
region near the center of the intermediate age galactic cluster NGC
7789. A CM diagram is presented for a sample of 1122 stars, which should
be complete down to V=20. On the ground of recent theoretical
evolutionary models, simulations of both the colour-magnitude diagram
and the cluster luminosity function are discussed under different
assumptions about age, mass function and binary population. We find that
the faint main sequence (V<15) appears rather depopulated of stars,
with a distribution of luminosity lower than that expected in the case
of a Salpeter's mass function. The distribution of post main sequence
stars in the various evolutionary phases is well reproduced by classical
models (i.e. with negligible overshooting of the unstable convective
layers). Data are best fitted by models having an age of 1.2Gyr. Derived
values for distance modulus and reddening are in agreement with previous
evaluations. We obtain V-M_v_=12.3+/-0.2 and E(B-V)=0.32+/-0.03.