MASS-TO-LIGHT RATIOS FOR M31 GLOBULAR CLUSTERS: AGE DATING AND A SURPRISING METALLICITY TREND
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
- UCO/Lick Observatory, Santa Cruz, CA 95064 (United States)
- Utrecht University, Utrecht (Netherlands)
We have obtained velocity dispersions from Keck high-resolution integrated spectroscopy of 10 M31 globular clusters (GCs), including three candidate intermediate-age GCs. We show that these candidates have the same V-band mass-to-light (M/L{sub V} ) ratios as the other GCs, implying that they are likely to be old. We also find a trend of derived velocity dispersion with wavelength, but cannot distinguish between a systematic error and a physical effect. Our new measurements are combined with photometric and spectroscopic data from the literature in a re-analysis of all M31 GC M/L{sub V} values. In a combined sample of 27 GCs, we show that the metal-rich GCs have lower M/L{sub V} than the metal-poor GCs, in conflict with predictions from stellar population models. Fragmentary data for other galaxies support this observation. The M31 GC fundamental plane is extremely tight, and we follow up an earlier suggestion by Djorgovski to show that the fundamental plane can be used to estimate accurate distances (potentially 10% or better)
- OSTI ID:
- 21301673
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 2 Vol. 138; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
Similar Records
STRUCTURAL PARAMETERS FOR GLOBULAR CLUSTERS IN THE OUTER HALO OF M31
KINEMATICS OF OUTER HALO GLOBULAR CLUSTERS IN M31