期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 694, 期 2, 页码 L144-L147出版社
IOP Publishing Ltd
DOI: 10.1088/0004-637X/694/2/L144
关键词
dark matter; galaxies: dwarf; galaxies: kinematics and dynamics; Local Group
资金
- STFC
- NSF [AST-0206081, 0507453, 0808043, AST-0205790, 0505711, 0807498]
- Science and Technology Facilities Council [ST/H004165/1, PP/E00105X/1, ST/F001967/1, PP/C002229/1, PP/E001068/1, ST/H004157/1] Funding Source: researchfish
- STFC [PP/E001068/1, PP/C002229/1, ST/H004157/1, ST/F001967/1, ST/H004165/1, PP/E00105X/1] Funding Source: UKRI
- Direct For Mathematical & Physical Scien [0808043] Funding Source: National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Mathematical Sciences [0505711] Funding Source: National Science Foundation
- Division Of Astronomical Sciences [0808043] Funding Source: National Science Foundation
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [0507453, 807498] Funding Source: National Science Foundation
We present a spectroscopic study of Leo V, a recently discovered satellite of the Milky Way ( MW). From stellar spectra obtained with the MMT/Hectochelle spectrograph we identify seven likely members of Leo V. Five cluster near the Leo V center ( R < 3') and have a velocity dispersion of 2.4(-1.4)(+2.4) km s(-1). The other two likely members lie near each other but far from the center (R similar to 13' similar to 700 pc) and inflate the globalvelocity dispersion to 3.3(-2.5)(+9.1) x 10(5)M(circle dot) (M/L-V = 75(-58)(+230)[M/L-V](circle dot)). From the stacked spectrum of the five central members we estimate a mean metallicity of [Fe/H]= -2.0 +/- 0.2 dex. Thus, with respect to dwarf spheroidals of similarluminosity, Leo V is slightly less massive and slightly more metal rich. Since we resolve the central velocity dispersion only marginally, we do not rule out the possibility that Leo V is a diffuse star cluster devoid of dark matter. The wide separation of its two outer members implies Leo V is losing mass; however, its large distance (D similar to 180 kpc) is difficult to reconcile with MW tidal stripping unless the orbit is very radial.
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