期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 776, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/776/2/L19
关键词
Galaxy: bulge; Galaxy: stellar content; Galaxy: structure; stars: variables: RR Lyrae
资金
- BASAL CATA Center for Astrophysics and Associated Technologies [PFB-06]
- Ministry for the Economy, Development, and Tourism's Programa Iniciativa Cientifica Milenio [P07-021-F]
- FONDECYT [1130196, 1110326, 1110393]
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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