Bibcode
Vallenari, A.; Aparicio, A.; Fagotto, F.; Chiosi, C.
Referencia bibliográfica
Astronomy and Astrophysics (ISSN 0004-6361), vol. 284, no. 2, p. 424-436
Fecha de publicación:
4
1994
Número de citas
23
Número de citas referidas
23
Descripción
We present Johnson CCD photometry in the B and V passbands for the
stellar content of two intermediate age star clusters of the Large
Magellanic Cloud (LMC), NGC 2134 and NGC 2249. In total 1613 stars are
measured in NGC 2134 and 850 in NGC 2249. With the aid of two grids of
stellar models calculated with convective overshoot (both from the core
and the envelope) and different radiative opacities, we examine the
color-magnitude diagrams (CMDs) and luminosity functions (LFs) of the
clusters and estimate reddening, metallicity, and age. The opacities in
usage are either the classical ones by Huebner et al. (1977)
(therinafter LAOL) or those by Iglesias et al. (1992) (therinafter
OPAL). Adopting the distance modulus of (m - M0) = 18.5 mag,
we find that stellar models with metallicity Z = 0.008 are best suited
to matech the main features of the observed CMDs. Accordingly, we get
E(B-V) = 0.22 and the age of 1.9 x 108 yr for NGC
2134, and E(B-V) = 0.25 and the age of 5.5 x 108
yr for NGC 2249. Similar analysis is made using both the opacity source
(OPAL or LAOL) bringing into evidence the major differences. Finally,
for the sake of comparison we also examine the CMDs and LFs by means of
models with identical opacities but the classical scheme of mixing. The
LFs indicate that classical models with OPAL require unusually steep
slopes of the initial mass function (IMF), x = 3.35 or greater, whereas
models with overshoot and OPAL are consistent with the classical slope,
x = 2.35.