Exploring halo substructure with giant stars: Spectroscopy of stars in the Galactic anticenter stellar structure

被引:126
作者
Crane, JD [1 ]
Majewski, SR [1 ]
Rocha-Pinto, HJ [1 ]
Frinchaboy, PM [1 ]
Skrutskie, MF [1 ]
Law, DR [1 ]
机构
[1] Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA
基金
美国国家科学基金会; 美国国家航空航天局;
关键词
galaxies : interactions; Galaxy : disk; Galaxy : structure;
D O I
10.1086/378767
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
To determine the nature of the recently discovered, ringlike stellar structure at the Galactic anticenter, we have collected spectra of a set of presumed constituent M giants selected from the Two Micron All Sky Survey Point Source Catalog. Radial velocities have been obtained for stars spanning similar to100degrees, exhibiting a trend in velocity with Galactic longitude and an estimated dispersion of sigma(v) = 20 +/- 4 km s(-1). A mean metallicity [Fe/H] = -0.4 +/- 0.3 measured for these stars combines with previous evidence from the literature to suggest a population with a significant metallicity spread. In addition, a curious alignment of at least four globular clusters of lower mean metallicity is noted to be spatially and kinematically consistent with this stellar distribution. We interpret the M giant sample position and velocity variation with Galactic longitude as suggestive of a satellite galaxy currently undergoing tidal disruption in a noncircular, prograde orbit about the Milky Way.
引用
收藏
页码:L119 / L122
页数:4
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