1995/11/07 by M. Catelan, J. A. de Freitas Pacheco · 20 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Cluster (spacecraft) #Ejecta #Galaxy #Gamma-ray bursts and supernovae #Globular cluster #Horizontal branch #Physics #Red giant #Red-giant branch #Stars #Stellar, planetary, and galactic studies #Supernova #astro-ph
paper · pdf · doi:10.1086/133705
published in Publications of the Astronomical Society of the Pacific 108, 166 (Institute of Physics) · 18 pages, LaTeX file (requires AAS LaTeX macro v4.0). Two tables and five figures available upon request. To appear in PASP (February 1996 issue)
arxiv created 1995/11/07 · openalex publication_date 1996/02/01 · openalex created_date 2016/06/24 · arxiv updated 2016/08/30 · openalex updated_date 2026/08/05
Morphological aspects of the V, B-V diagram of metal-rich globular clusters are analyzed, on the basis of stellar evolution models for horizontal-branch (HB) and red giant branch stars. These have been incorporated into detailed synthetic HB models, the influence of differential reddening upon which is also discussed. The synthetic HB models are found to be very clumpy in the color-magnitude diagram, though more extended structures occasionally result due to the effect of evolution away from the zero-age HB. In particular, "sloped" clumps may be naturally expected for sufficiently high helium abundances. Differential reddening is found to have a smaller influence than evolution itself upon the morphology of the clump. The synthetic HB models are also used to study the age difference between metal-rich clusters on the basis of the "Delta-V" method. We emphasize the importance of knowing in advance the relative abundances of helium and metals in order to estimate this age difference quantitatively. We present chemical evolution models that serve to illustrate the effect, and show that, for two clusters of identical [Fe/H] and Delta-V, the one enriched predominantly by ejecta from supernovae type II explosions will appear younger than the other which also suffered enrichment from supernovae type Ia ejecta. The implied locations of the red giant branch feature known as the "bump" are also discussed on the basis of recent observational and theoretical results. Our corresponding predictions should be checked against accurate observational data obtained with the Hubble Space Telescope.