VVV SURVEY NEAR-INFRARED PHOTOMETRY OF KNOWN BULGE RR LYRAE STARS: THE DISTANCE TO THE GALACTIC CENTER AND ABSENCE OF A BARRED DISTRIBUTION OF THE METAL-POOR POPULATION

被引:131
作者
Dekany, I. [1 ,4 ]
Minniti, D. [1 ,4 ,5 ]
Catelan, M. [1 ,4 ]
Zoccali, M. [1 ,4 ]
Saito, R. K. [2 ]
Hempel, M. [1 ,4 ]
Gonzalez, O. A. [3 ]
机构
[1] Pontificia Univ Catolica Chile, Inst Astrofis, Fac Fis, Santiago 7820436, Chile
[2] Univ Fed Sergipe, Dept Fis, BR-49100000 Sao Cristovao, SE, Brazil
[3] European So Observ, Santiago 19, Chile
[4] Milky Way Millennium Nucleus, Santiago 7820436, Chile
[5] Vatican Observ, I-00120 Vatican City, Vatican
关键词
Galaxy: bulge; Galaxy: stellar content; Galaxy: structure; stars: variables: RR Lyrae; MILKY-WAY BULGE; MASSIVE BLACK-HOLE; RED CLUMP GIANTS; OGLE-III; METALLICITY MAPS; EXTINCTION MAP; LIGHT CURVES; DATA RELEASE; 2MASS; ABUNDANCES;
D O I
10.1088/2041-8205/776/2/L19
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have combined optical and near-infrared data of known RR Lyrae (RRL) stars in the bulge in order to study the spatial distribution of its metal-poor component by measuring precise reddening values and distances of 7663 fundamental-mode RRL stars with high-quality photometry. We obtain a distance to the Galactic center of R-0 = 8.33 +/- 0.05 +/- 0.14 kpc. We find that the spatial distribution of the RRL stars differs from the structures traced by the predominantly metal-rich red clump (RC) stars. Unlike the RC stars, the RRL stars do not trace a strong bar, but have a more spheroidal, centrally concentrated distribution, showing only a slight elongation in its very center. We find a hint of bimodality in the density distribution at high southern latitudes (b < -5 degrees), which needs to be confirmed by extending the areal coverage of the current census. The different spatial distributions of the metal-rich and metal-poor stellar populations suggest that the Milky Way has a composite bulge.
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页数:5
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