A Multi-epoch Kinematic Study of the Remote Dwarf Spheroidal Galaxy Leo II

被引：33

作者：

Spencer, Meghin E. ^{[1
]}

Mateo, Mario ^{[1
]}

Walker, Matthew G. ^{[2
]}

Olszewski, Edward W. ^{[3
]}

机构：

[1] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA

[2] Carnegie Mellon Univ, Dept Phys, McWilliams Ctr Cosmol, Pittsburgh, PA 15213 USA

[3] Univ Arizona, Steward Observ, Tucson, AZ USA

来源：

ASTROPHYSICAL JOURNAL | 2017年 / 836卷 / 02期

基金：

美国国家科学基金会;

关键词：

galaxies: abundances; galaxies: dwarf; galaxies: individual (Leo II); galaxies: kinematics and dynamics; MULTIELEMENT ABUNDANCE MEASUREMENTS; EXPLORING HALO SUBSTRUCTURE; MILKY-WAY; SATELLITE GALAXIES; LOCAL GROUP; INTERNAL KINEMATICS; DSPH GALAXIES; GIANT STARS; FORNAX; MASS;

D O I：

10.3847/1538-4357/836/2/202

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We conducted a large spectroscopic survey of 336 red giants in the direction of the Leo II dwarf galaxy using Hectochelle on the Multiple Mirror Telescope, and we conclude that 175 of them are members based on their radial velocities and surface gravities. Of this set, 40 stars have never before been observed spectroscopically. The systemic velocity of the dwarf is 78.3 +/- 0.6 km s(-1) with a velocity dispersion of 7.4 +/- 0.4 km s(-1). We identify one star beyond the tidal radius of Leo II but find no signatures of uniform rotation, kinematic asymmetries, or streams. The stars show a strong metallicity gradient of -1.53 +/- 0.10 dex kpc(-1) and have a mean metallicity of -1.70 +/- 0.02 dex. There is also evidence of two different chemodynamic populations, but the signal is weak. A larger sample of stars would be necessary to verify this feature.

引用

页数：10

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