来自 MACHO 数据库的银河盘中 RR Lyrae 恒星群
摘要
Presented are the mean colors and magnitudes of RR Lyrae stars in 24 fields towards the Galactic bulge from the MACHO database. 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 in the inner fields closer to the Galactic center (l<4, b>-4) 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 and the clump giants trace two different populations. The RR Lyrae would represent the inner extension of the Galactic halo in these fields.
引用
@article{arxiv.astro-ph/9707311,
title = {The RR Lyrae Population of the Galactic Bulge from the MACHO Database},
author = {The MACHO Collaboration and C. Alcock and R. A. Allsman and D. R. Alves and T. S. Axelrod and A. Basu and L. Baskett and A. Becker and D. P. Bennett and K. H. Cook and K. C. Freeman and K. Griest and M. J. Lehner and S. L. Marshall and D. Minniti and B. A. Peterson and M. R. Pratt and P. J. Quinn and A. W. Rodgers and C. W. Stubbs and W. Sutherland and A. Tomaney and T. Vandehei and D. L. Welch},
journal= {arXiv preprint arXiv:astro-ph/9707311},
year = {2007}
}
备注
29 pages including 11 PostScript figures, uses aaspp4.sty. To appear in The Astrophysical Journal