The RR Lyrae population of the Galactic bulge from the MACHO database: Mean colors and magnitudes

Journal Article · Thu Jan 01 00:00:00 EST 1998 · Astrophysical Journal

DOI:https://doi.org/10.1086/305017· OSTI ID:627543

Alcock, C ^[1]; Allsman, R A ^[1]; Alves, D R ^[1]; Axelrod, T S ^[1]; Becker, A C ^[2]; Basu, A; Baskett, L ^[1]; Bennett, D P; Cook, K H ^[1]; Freeman, K C ^[3]; others, and

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1. Lawrence Livermore National Laboratory, P.O. Box 808, 7000 East Avenue, Livermore, California94550 (United States)
2. Center for Particle Astrophysics, 301 Le Conte Hall, University of California at Berkeley, Berkeley, California94720 (United States)
3. Mount Stromlo and Siding Spring Observatories, Australian National University, Private Bag, Weston Creek, ACT2611 (Australia)

Mean colors and magnitudes of RR Lyrae stars in 24 fields toward the Galactic bulge from the MACHO database are presented. Accurate mean reddenings are computed for these fields on the basis of the mean colors. The distribution along the line of sight of the RR Lyrae population is examined on the basis of the mean magnitudes, and it is shown that the bulk of the RR Lyrae population is not barred. Only the RR Lyrae stars in the inner fields closer to the Galactic center (l{lt}4{degree}, b{gt}{minus}4{degree}) show evidence for a bar. The red giant clump stars in the MACHO fields, however, clearly show a barred distribution, confirming the results of previous studies. Given the different spatial distribution, the RR Lyrae stars and the clump giants trace two different populations. The RR Lyrae variables would represent the inner extension of the Galactic halo in these fields. {copyright} {ital 1998} {ital The American Astronomical Society}

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 627543
• Journal Information: Astrophysical Journal, Vol. 492, Issue 1; Other Information: PBD: Jan 1998
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
GALAXY NUCLEI
VARIABLE STARS
DATA ANALYSIS
GRAVITATIONAL LENSES
GIANT STARS
ELEMENT ABUNDANCE