Measuring age differences among globular clusters having similar metallicities - A new method and first results

Abstract

view Abstract Citations (328) References (71) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Measuring Age Differences among Globular Clusters Having Similar Metallicities: A New Method and First Results Vandenberg, Don A. ; Bolte, Michael ; Stetson, Peter B. Abstract A color-difference technique for estimating the relative ages of globular clusters with similar chemical compositions on the basis of their CM diagrams is described and demonstrated. The theoretical basis and implementation of the procedure are explained, and results for groups of globular clusters with m/H = about -2, -1.6, and -1.3, and for two special cases (Palomar 12 and NGC 5139) are presented in extensive tables and graphs and discussed in detail. It is found that the more metal-deficient globular clusters are nearly coeval (differences less than 0.5 Gyr), whereas the most metal-rich globular clusters exhibit significant age differences (about 2 Gyr). This result is shown to contradict Galactic evolution models postulating halo collapse in less than a few times 100 Myr. Publication: The Astronomical Journal Pub Date: August 1990 DOI: 10.1086/115529 Bibcode: 1990AJ....100..445V Keywords: Color-Magnitude Diagram; Globular Clusters; Metallic Stars; Metallicity; Stellar Composition; Astronomical Photometry; Chemical Composition; Interstellar Extinction; Star Clusters; Statistical Analysis; Stellar Evolution; Astrophysics; CLUSTERS: GLOBULAR full text sources ADS | data products SIMBAD (22)