Tidal streams in the galactic halo:: Evidence for the Sagittarius northern stream or traces of a new nearby dwarf galaxy

被引:79
作者
Martínez-Delgado, D [1 ]
Aparicio, A
Gómez-Flechoso, MA
Carrera, R
机构
[1] Inst Astrofis Canarias, E-38205 Tenerife, Canary Islands, Spain
[2] Univ La Laguna, Dept Astrofis, E-38200 La Laguna, Tenerife, Spain
[3] Observ Geneva, CH-1290 Sauverny, Switzerland
关键词
galaxy : evolution; galaxy : formation; galaxy : halo; galaxies : individual (Sagittarius); galaxy : structure;
D O I
10.1086/319167
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Standard cosmology predicts that dwarfs were the first galaxies to be formed in the universe and that many of them merge afterward to form bigger galaxies such as the Milky Way. This process would have left behind traces such as tidal debris or star streams in the outer halo. We report here the detection of a very low density stellar system at 50 +/- 10 kpc from the Galactic center that could be related to the merger process. It could form part of the Sagittarius northern stream or, alternatively, could be the trace of a hitherto unknown dwarf galaxy. The dwarf galaxy in Sagittarius, the closest satellite of the Milky Way, is currently being tidally disrupted and is a "living" test for galaxy formation theories. The system found here is 60 degrees away from the center of the Sagittarius galaxy. If it is really associated with this galaxy, it would confirm predictions of dynamical interaction models indicating that tidal debris from Sagittarius could extend along a stream completely enveloping the Milky Way in a polar orbit.
引用
收藏
页码:L199 / L202
页数:4
相关论文
共 24 条
[1]  
BERTELLI G, 1994, ASTRON ASTROPHYS SUP, V106, P275
[2]   The absolute proper motion of Palomar 12: A case for tidal capture from the Sagittarius dwarf spheroidal galaxy [J].
Dinescu, DI ;
Majewski, SR ;
Girard, TM ;
Cudworth, KM .
ASTRONOMICAL JOURNAL, 2000, 120 (04) :1892-1905
[3]   The star formation history of the Local Group dwarf galaxy Leo I [J].
Gallart, C ;
Freedman, WL ;
Aparicio, A ;
Bertelli, G ;
Chiosi, C .
ASTRONOMICAL JOURNAL, 1999, 118 (05) :2245-2261
[4]  
Gómez-Flechoso MA, 1999, ASTRON ASTROPHYS, V347, P77
[5]  
HELMI A, 2001, IN PRESS MNRAS
[6]   Galactic halo substructure in the Sloan Digital Sky Survey: The ancient tidal stream from the Sagittarius dwarf galaxy [J].
Ibata, R ;
Irwin, M ;
Lewis, GF ;
Stolte, A .
ASTROPHYSICAL JOURNAL, 2001, 547 (02) :L133-L136
[7]  
IBATA R, 2001, IN PRESS AJ
[8]   Galactic indigestion: Numerical simulations of the Milky Way's closest neighbor [J].
Ibata, RA ;
Lewis, GF .
ASTROPHYSICAL JOURNAL, 1998, 500 (02) :575-590
[9]   The kinematics, orbit, and survival of the Sagittarius dwarf spheroidal galaxy [J].
Ibata, RA ;
Wyse, RFG ;
Gilmore, G ;
Irwin, MJ ;
Suntzeff, NB .
ASTRONOMICAL JOURNAL, 1997, 113 (02) :634-655
[10]   A DWARF SATELLITE GALAXY IN SAGITTARIUS [J].
IBATA, RA ;
GILMORE, G ;
IRWIN, MJ .
NATURE, 1994, 370 (6486) :194-196