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The distance from the Sun to the centre and the shape of the old bulge in the Galaxy: 16 221 OGLE RR Lyrae stars
Monthly Notices of the Royal Astronomical Society ( IF 4.8 ) Pub Date : 2020-09-23 , DOI: 10.1093/mnras/staa2845
Griv E, Gedalin M, Pietrukowicz P, et al.

ABSTRACT
A statistical method is used to determine both the Sun’s distance r0 from the Galactic Centre and the 3D structure of the old stellar population of the Galactic bulge. The space distribution of 16 221 high latitude type-RRab RR Lyrae stars from the optical OGLE survey located towards the bulge is explored. An estimate by using RR Lyraes leads to a mean r0 = 8.28 ± 0.14 kpc within the effective bulge radius of rbulge = 2–3 kpc. The distribution of RR Lyraes within rbulge has the shape of an ellipsoid slightly elongated almost towards the Sun with a major axis of its symmetry a and two minor axes b and c of about the same length. The axial ratio is a: b: c ≈ 1: 0.7: 0.7. These age-old, metal-poor, and kinematically hot stars do not trace a strong bar-like structure in the direction of the bulge at distances >1 kpc from the Galactic Centre, as b/a ∼ 1.


中文翻译:

太阳到中心的距离以及星系中旧凸起的形状:16 221个OGLE RR天琴星

摘要
使用统计方法确定太阳到银河系中心的距离r 0和银河系凸起的旧恒星种群的3D结构。研究了从光学OGLE测向凸出处的16221颗高纬度RRab RR天琴座星的空间分布。使用RR Lyraes进行的估算得出 在r凸出 = 2–3 kpc的有效凸出半径内的平均值r 0 = 8.28±0.14 kpc。RR琴琴在r凸起内的分布呈椭圆形,几乎对称于太阳,其主轴长为a,两个短轴为bc大约相同的长度。轴比是一个bc ^ ≈1:0.7:0.7。这些年代久远,贫金属,和运动学热星不会在距离>从银河中心1个KPC,如迹在凸出的方向上的强棒状结构b /〜1。
更新日期:2020-10-13
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