A Ghost in Bootes: The Least-Luminous Disrupted Dwarf Galaxy

被引：3
|
作者：
Chandra, Vedant [1 ]
Conroy, Charlie [1 ]
Caldwell, Nelson [1 ]
Bonaca, Ana [2 ]
Naidu, Rohan P. P. [1 ]
Zaritsky, Dennis [3 ,4 ]
Cargile, Phillip A. A. [1 ]
Han, Jiwon Jesse [1 ]
Johnson, Benjamin D. D. [1 ]
Speagle, Joshua S. S. [5 ,6 ,7 ]
Ting, Yuan-Sen [8 ,9 ]
Woody, Turner [1 ]
机构：
[1] Ctr Astrophys Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138 USA
[2] Observ Carnegie Inst Sci, 813 Santa Barbara St, Pasadena, CA 91101 USA
[3] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA
[4] Univ Arizona, Dept Astron, Tucson, AZ 85721 USA
[5] Univ Toronto, David A Dunlap Dept Astron & Astrophys, 50 St George St, Toronto, ON M5S 3H4, Canada
[6] Univ Toronto, Dunlap Inst Astron & Astrophys, 50 St George St, Toronto, ON M5S 3H4, Canada
[7] Univ Toronto, Dept Stat Sci, 100 St George St, Toronto, ON M5S 3G3, Canada
[8] Australian Natl Univ, Res Sch Astron & Astrophys, Cotter Rd, Weston, ACT 2611, Australia
[9] Australian Natl Univ, Sch Comp, Acton, ACT 2601, Australia
来源：
ASTROPHYSICAL JOURNAL | 2022年 / 940卷 / 02期
关键词：
MILKY-WAY SATELLITES; STELLAR STREAMS; SPECTROSCOPIC SURVEY; TIDAL STREAMS; HALO; MASS; STREAMFINDER; KINEMATICS; DEBRIS; VIEW;
D O I：
10.3847/1538-4357/ac9b4b
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
We report the discovery of Specter, a disrupted ultrafaint dwarf galaxy revealed by the H3 Spectroscopic Survey. We detected this structure via a pair of comoving metal-poor stars at a distance of 12.5 kpc, and further characterized it with Gaia astrometry and follow-up spectroscopy. Specter is a 25 degrees x 1 degrees stream of stars that is entirely invisible until strict kinematic cuts are applied to remove the Galactic foreground. The spectroscopic members suggest a stellar age tau greater than or similar to 12 Gyr and a mean metallicity <[Fe/H]> = -1.84(-0.18)(+0.16), with a significant intrinsic metallicity dispersion sigma([Fe/H]) = 0.37(-0.13)(+0.21). We therefore argue that Specter is the disrupted remnant of an ancient dwarf galaxy. With an integrated luminosity M-v approximate to -2.6, Specter is by far the least-luminous dwarf galaxy stream known. We estimate that dozens of similar streams are lurking below the detection threshold of current search techniques, and conclude that spectroscopic surveys offer a novel means to identify extremely low surface brightness structures.
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页数：11
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