천문학회보 (The Bulletin of The Korean Astronomical Society)
- 제38권2호
- /
- Pages.37.1-37.1
- /
- 2013
- /
- 1226-2692(pISSN)
Optical and Near-IR Photometry of the NGC 4874 Globular Cluster System with the Hubble Space Telescope
- Cho, Hyejeon (Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University) ;
- Blakeslee, John P. (Herzberg Institute of Astrophysics, National Research Council of Canada (NRC-HIA)) ;
- Peng, Eric W. (Department of Astronomy, Peking University) ;
-
Lee, Young-Wook
(Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University)
- 발행 : 2013.10.08
초록
We present our study of analyzing the photometric properties of the globular cluster (GC) system which resides in the extended halo of the central bright Coma cluster galaxy NGC 4874. The core of the Coma cluster of galaxies (Abell 1656) was observed with both the HST Advanced Camera for Surveys (ACS) in the F475W (g475) and F814W (I814) and Wide Field Camera 3 IR Channel (WFC3/IR) in the F160W (H160) filters. The data analysis procedure and GC candidate selection criteria are briefly described. We investigate the interesting "tilt" features in color-magnitude diagrams for this GC system and their link to the nonlinear color-metallicity relation for GCs. The NGC 4874's GC system exhibits a bimodal distribution in the optical g475-I814 color and much more than half the GCs fall in the red side at g475-I814 ~ 1.1. This bimodality is weakened in the optical-IR I814-H160 color; the quantitative analysis on the features of both color distributions using the Gaussian Mixture Modeling code proves the bimodalities are different. Both colors, thus, cannot linearly reflect the bimodality of an underlying metallicity, supporting the suggestion that observed bimodalities in extragalactic GC colors are the metallicity-to-color projection effect.
키워드