Ages and structural and dynamical parameters of two globular clusters in the M81 group
| Autor: | Ma, Jun, Wang, Song, Wu, Zhenyu, Zhang, Tianmeng, Zou, Hu, Nie, Jundan, Zhou, Zhiming, Zhou, Xu, Peng, Xiyang, Wang, Jiali, Wu, Jianghua, Du, Cuihua, Yuan, Qirong |
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| Rok vydání: | 2017 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/stx761 |
| Popis: | GC-1 and GC-2 are two globular clusters (GCs) in the remote halo of M81 and M82 in the M81 group discovered by Jang et al. using the {\it Hubble Space Telescope} ({\it HST}) images. These two GCs were observed as part of the Beijing--Arizona--Taiwan--Connecticut (BATC) Multicolor Sky Survey, using 14 intermediate-band filters covering a wavelength range of 4000--10000 \AA. We accurately determine these two clusters' ages and masses by comparing their spectral energy distributions (from 2267 to 20000~{\AA}, comprising photometric data in the near-ultraviolet of the {\it Galaxy Evolution Explorer}, 14 BATC intermediate-band, and Two Micron All Sky Survey near-infrared $JHK_{\rm s}$ filters) with theoretical stellar population-synthesis models, resulting in ages of $15.50\pm3.20$ for GC-1 and $15.10\pm2.70$ Gyr for GC-2. The masses of GC-1 and GC-2 obtained here are $1.77-2.04\times 10^6$ and $5.20-7.11\times 10^6 \rm~M_\odot$, respectively. In addition, the deep observations with the Advanced Camera for Surveys and Wide Field Camera 3 on the {\it HST} are used to provide the surface brightness profiles of GC-1 and GC-2. The structural and dynamical parameters are derived from fitting the profiles to three different models; in particular, the internal velocity dispersions of GC-1 and GC-2 are derived, which can be compared with ones obtained based on spectral observations in the future. For the first time, in this paper, the $r_h$ versus $M_V$ diagram shows that GC-2 is an ultra-compact dwarf in the M81 group. Comment: MNRAS 468, 4513-4528 (2017), 16 pages, 9 figures and 11 tables |
| Databáze: | arXiv |
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