Abstract
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°), 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.
Original language | English |
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Article number | L19 |
Journal | Astrophysical Journal Letters |
Volume | 776 |
Issue number | 2 |
DOIs | |
Publication status | Published - 20 Oct 2013 |
Keywords
- Galaxy: bulge
- Galaxy: stellar content
- Galaxy: structure
- stars: variables: RR Lyrae
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science