The quest RR Lyrae survey:: Confirmation of the clump at 50 kiloparsecs and other overdensities in the outer halo

被引:182
作者
Vivas, AK
Zinn, R
Andrews, P
Bailyn, C
Baltay, C
Coppi, P
Ellman, N
Girard, T
Rabinowitz, D
Schaefer, B
Shin, J
Snyder, J
Sofia, S
van Altena, W
Abad, C
Bongiovanni, A
Briceño, C
Bruzual, G
Della Prugna, F
Herrera, D
Magris, G
Mateu, J
Pacheco, R
Sánchez, G
Sánchez, G
Schenner, H
Stock, J
Vicente, E
Vieira, K
Ferrín, I
Hernandez, J
Gebhard, M
Honeycutt, R
Mufson, S
Musser, J
Rengstorf, A
机构
[1] Yale Univ, Dept Astron, New Haven, CT 06520 USA
[2] Yale Univ, Dept Phys, New Haven, CT 06520 USA
[3] Univ Texas, Dept Astron, Austin, TX 78712 USA
[4] Ctr Invest Astron CIDA, Merida 5101 A, Venezuela
[5] Univ Los Andes, Dept Fis 5101, Merida, Venezuela
[6] Indiana Univ, Dept Astron, Bloomington, IN 47405 USA
关键词
galaxies : individual (Sagittarius); Galaxy : halo; Galaxy : structure; stars : variables : other;
D O I
10.1086/320915
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have measured the periods and light curves of 148 RR Lyrae variables from V = 13.5 to 19.7 from the first 100 deg(2) of the Quasar Equatorial Survey Team RR Lyrae survey. Approximately 55% of these stars belong to the dump of stars detected earlier by the Sloan Digital Sky Survey. According to our measurements, this feature has similar to 10 times the background density of halo stars, spans at least 37.degrees5 by 3.degrees5 in alpha and delta (greater than or equal to 30 by greater than or equal to3 kpc), lies similar to 50 kpc from the Sun, and has a depth along the line of sight of similar to5 kpc (1 sigma). These properties are consistent with the recent models that suggest that it is a tidal stream from the Sagittarius dwarf spheroidal galaxy. The mean period of the type ab variables, 0.58 days, is also consistent. In addition, we have found two smaller overdensities in the halo, one of which may be related to the globular cluster Pal 5.
引用
收藏
页码:L33 / L36
页数:4
相关论文
共 27 条
[1]   The baryon halo of the Milky Way: A fossil record of its formation [J].
Bland-Hawthorn, J ;
Freeman, K .
SCIENCE, 2000, 287 (5450) :79-84
[2]   The metallicity dependence of RR Lyrae absolute magnitudes from synthetic horizontal-branch models [J].
Demarque, P ;
Zinn, R ;
Lee, YW ;
Yi, S .
ASTRONOMICAL JOURNAL, 2000, 119 (03) :1398-1404
[3]   The Ross 451 group of halo stars [J].
Eggen, OJ .
ASTRONOMICAL JOURNAL, 1996, 112 (06) :2661-2666
[5]   Building up the stellar halo of the Galaxy [J].
Helmi, A ;
White, SDM .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1999, 307 (03) :495-517
[6]   Debris streams in the solar neighbourhood as relicts from the formation of the Milky Way [J].
Helmi, A ;
White, SDM ;
de Zeeuw, PT ;
Zhao, HS .
NATURE, 1999, 402 (6757) :53-55
[7]   Simple dynamical models of the Sagittarius dwarf galaxy [J].
Helmi, A ;
White, SDM .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2001, 323 (03) :529-536
[8]  
Hogg H. S., 1973, 3 CATALOGUE VARIABLE
[9]   Great circle tidal streams: Evidence for a nearly spherical massive dark halo around the Milky Way [J].
Ibata, R ;
Lewis, GF ;
Irwin, M ;
Totten, E ;
Quinn, T .
ASTROPHYSICAL JOURNAL, 2001, 551 (01) :294-311
[10]   A DWARF SATELLITE GALAXY IN SAGITTARIUS [J].
IBATA, RA ;
GILMORE, G ;
IRWIN, MJ .
NATURE, 1994, 370 (6486) :194-196