期刊
ASTROPHYSICAL JOURNAL
卷 751, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/751/2/130
关键词
galaxies: dwarf; Galaxy: halo; stars: abundances
资金
- National Natural Science Foundation of China [11178013, 11073026, 11150110135, 10978015]
- Provincial Natural Science Foundation of ShanDong [Y2008A08, ZR2010AM006]
We have selected 556 red horizontal branch stars along the streams of the Sagittarius (Sgr) dwarf galaxy from Sloan Digital Sky Survey DR7 spectroscopic data using a theoretical model. The metallicity and alpha-element distributions are investigated for stars in the Sgr streams and for Galactic stars at the same locations. We find that the Sgr stars have two peaks in the metallicity distribution while the Galactic stars have a more prominent metal-poor peak. Meanwhile, [alpha/Fe] ratios of the Sgr stars are lower than those of the Galactic stars. Among the Sgr stars, we find a difference in the metallicity distribution between the leading and trailing arms of the Sgr tidal tails. The metallicity and [alpha/Fe] distribution of the leading arm is similar to that of the Galaxy. The trailing arm is composed mainly of a metal-rich component and [alpha/Fe] is obviously lower than that of the Galactic stars. The metallicity gradient is -(1.8 +/- 0.3) x10(-3) dex deg(-1) in the first wrap of the trailing arm and -(1.5 +/- 0.4) x10(-3) dex deg(-1) in the first wrap of the leading arm. No significant gradient exists along the second wraps of the leading or trailing arms. It seems that the Sgr dwarf galaxy initially lost the metal-poor component in the second wrap (older) arms due to the tidal force of our Galaxy and then the metal-rich component is disrupted in the first wrap (younger) arms. Finally, we found that the velocity dispersion of the trailing arm from 88 degrees < Lambda(circle dot) < 112 degrees is sigma = 9.808 +/- 1.0 km s(-1), which is consistent with previous work in the literature.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据