2000/01/25 by Leo Girardi, L. Girardi, Girardi, Leo
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0001434
6 pages, to appear in proc. of Strasbourg workshop "Massive Stellar Clusters", ASP Conf. Ser., eds. A. Lancon, C. Boily
arxiv created 2000/01/25 · openalex publication_date 2000/01/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We briefly review the main features in the broad-band colour evolution of star clusters, over the complete age interval from 107 to 10^(10) yr. The emphasis is in the problem of age-dating distant young clusters (<2 Gyr) from their integrated colours. It is shown that U-B and B-V are less sensitive to metallicity than colours involving red pass-bands, like V-I, at least up to ages of some few Gyr. Since U-B and B-V are determined by well-understood and well-populated evolutionary stages, they are also less affected by theoretical uncertainties and by the ubiquitous effect of stochastic colour dispersion. The latter effects become important for the V-K colour. Thus, we argue that U-B and B-V are, presently, the more suitable broad-band colours for age-dating distant clusters. For other potentially useful colours like V-R and V-I, empirical tests of their evolution are still missing.