MAPPING THE X-SHAPED MILKY WAY BULGE
MAPPING THE X-SHAPED MILKY WAY BULGE
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DOI：
10.1088/0004-6256/142/3/76
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发表时间：
2011-07
期刊：
影响因子：
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通讯作者：
R. Saito;M. Zoccali;A. McWilliam;D. Minniti;O. Gonzalez;V. Hill
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作者：
R. Saito;M. Zoccali;A. McWilliam;D. Minniti;O. Gonzalez;V. Hill
我们使用两微米全天巡天数据分析了整个银河系凸起的红团（RC）星的分布。我们绘制了区域内1 deg2区域中RC的位置|L| 8. ° 5和3. ° 5| B| 0.88 ° 5，总共170 deg2。在中心区域看到的单个RC在两个半球的高银河系边缘分裂成两个组成部分，由两个结构在沿着同一视线的不同距离产生。对于靠近l = 0 °轴的圆，在Z-X平面中X形状清晰可见。在明亮和暗淡的RC星群中，对RC星空间密度的粗略测量与采用的RC距离一致，提供了进一步的支持证据，证明X结构是真实的，并且在我们的凸起区域中存在近似的前后对称性。我们的结论是，银河系核球内部有一个X形结构，|L| 0.02 °，相对于视线几乎是从侧面看。为了区分可能导致观察到的X形结构的不同可能性，需要将扩展到最内部隆起区域的额外的深近红外测光与光谱数据相结合。
We analyzed the distribution of the red clump (RC) stars throughout the Galactic bulge using Two Micron All Sky Survey data. We mapped the position of the RC in 1 deg2 fields within the area |l| ⩽ 8.°5 and 3.°5 ⩽ |b| ⩽ 8.°5, for a total of 170 deg2. The single RC seen in the central area splits into two components at high Galactic longitudes in both hemispheres, produced by two structures at different distances along the same line of sight. The X-shape is clearly visible in the Z–X plane for longitudes close to the l = 0° axis. Crude measurements of the space densities of RC stars in the bright and faint RC populations are consistent with the adopted RC distances, providing further supporting evidence that the X-structure is real, and that there is approximate front–back symmetry in our bulge fields. We conclude that the Milky Way bulge has an X-shaped structure within |l| ≲ 2°, seen almost edge-on with respect to the line of sight. Additional deep near-infrared photometry extending into the innermost bulge regions combined with spectroscopic data is needed in order to discriminate among the different possibilities that can cause the observed X-shaped structure.