Globular clusters in M81
Abstract
We have performed a comprehensive spectroscopic and photometric analysis of the M81 globular cluster system, using HST ACS imaging in the B, V, and I bands and 74 globular cluster spectra from Hectospec at the MMT. M81 has over 200 globular clusters, about 100 of which have spectra. The M81 globular clusters have a bimodal metallicity distribution with peaks at [Fe/H] -1.6 and -0.9, and significant rotation in all subpopulations (similar to the globular cluster system of M31) whether the subpopulations are divided by distance from the center or metallicity. The metal-rich and inner (ɜ kpc) subpopulations have the highest rotation amplitudes. The dereddened globular cluster luminosity function peaks at V 20.2, giving a distance of 3.63 Mpc using the HST Key Project GCLF calibration (absolute magnitude of -7.6), in excellent agreement with previous distance estimates. The metal-rich and metal-poor globular clusters have similar effective radii. This research was supported by the NASA grant GO-10250 from the Space Telescope Science Institute and the National Science Foundation grant AST 0507229.
- Publication:
-
American Astronomical Society Meeting Abstracts #215
- Pub Date:
- January 2010
- Bibcode:
- 2010AAS...21534002N