Issue |
Astron. Astrophys. Suppl. Ser.
Volume 146, Number 1, October I 2000
|
|
---|---|---|
Page(s) | 91 - 101 | |
DOI | https://doi.org/10.1051/aas:2000357 | |
Published online | 15 October 2000 |
Predicted colours for simple stellar populations
II. The case of old stellar clusters
1
Osservatorio Astronomico di Collurania, Via M. Maggini, I-64100 Teramo, Italy e-mail: brocato, raimondo@astrte.te.astro.it
2
Istituto Nazionale di Fisica Nucleare, LNGS, L'Aquila, Italy
3
Dipartimento di Fisica, Università di Pisa, I-56100 Pisa, Italy e-mail: vittorio@astr18pi.difi.unipi.it
4
Istituto Nazionale di Fisica Nucleare, I-56100 Pisa, Italy
5
Associazione Euratrom-ENEA CRE, I-00044 Frascati, Italy e-mail: fpoli@frascati.enea.it
Send offprint request to: E. Brocato
Received:
10
February
2000
Accepted:
3
July
2000
This paper presents theoretical integrated colours of old stellar
populations as computed adopting an homogeneous set of stellar models,
covering all the major evolutionary phases of globular cluster
stars. We show that adopting Reimers parameterization of mass loss
rates, the choice gives synthetic CM diagrams of simple
stellar populations in agreement with the typical dependence of
globular cluster CM diagrams on metallicity. We present theoretical
,
,
and
integrated colours for
cluster metallicity in the range
to 0.02 and for age between 8
and 15 Gyr.
The stochastic occurrence of luminous post-AGB stars is briefly discussed.
We find that for an age
Gyr the predicted
integrated colours
appear in good agreement with available data for both galactic and LMC
old globulars. We discuss the uncertainties of integrated colours due to
statistical fluctuations in the number of luminous stars, giving for
each colour the expected uncertainty as a function of the cluster
integrated V-magnitude. Comparison with Kurth et al. (1999) discloses that
the still existing differences in the evolutionary results appear
of minor relevance as far as integrated cluster colours is concerned.
Finally, we show that reasonable uncertainties
either in the cluster age or in the efficiency of mass loss have
marginal effects on the predicted colours.
Key words: galaxy: globular clusters: general / galaxies: star clusters / galaxies: Magellanic Clouds / stars: AGB and post-AGB / Stars: Hertzsprung-Russel (HR) and C-M diagrams
© European Southern Observatory (ESO), 2000