THE X-SHAPED BULGE OF THE MILKY WAY REVEALED BY WISE
THE X-SHAPED BULGE OF THE MILKY WAY REVEALED BY WISE
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DOI：
10.3847/0004-6256/152/1/14
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发表时间：
2016-02
期刊：
影响因子：
--
通讯作者：
M. Ness;D. Lang
中科院分区：
文献类型：
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作者：
M. Ness;D. Lang
银河系凸起有一个盒子状/花生状的形态和一个X形的结构。这个X形的形状是由测光测量得到的“红色团块中的分裂”揭示的，它来自星星计数沿着朝向凸起的视线。这种四四方方的X形凸起形态并不是银河系所独有的，在其他棒旋星系中也观察到了这种凸起。N体模拟表明，盒状和X形凸起形成的磁盘通过动力学不稳定性。也有人提出银河系的球核不是X形的，而是在一个古老的经典球状球核中，红团星的明显分裂是不同恒星族群的结果。我们提出了一个宽视场红外巡天探测器（WISE）的银河系隆起的图像，通过下采样的公开可用的“unWISE”coadds。WISE拍摄的银河系核球图像表明，银河系核球的X形性质是不言而喻和无可辩驳的。X形凸起本身的形态和构成该结构内轨道的凸起恒星的比例对银河系的形成历史具有重要意义，并且，考虑到四方形X形凸起的普遍性，一般来说，螺旋星系。
The Milky Way bulge has a boxy/peanut morphology and an X-shaped structure. This X-shape has been revealed by the “split in the red clump” from star counts along the line of sight toward the bulge, measured from photometric surveys. This boxy, X-shaped bulge morphology is not unique to the Milky Way and such bulges are observed in other barred spiral galaxies. N-body simulations show that boxy and X-shaped bulges are formed from the disk via dynamical instabilities. It has also been proposed that the Milky Way bulge is not X-shaped, but rather, the apparent split in the red clump stars is a consequence of different stellar populations, in an old classical spheroidal bulge. We present a Wide-Field Infrared Survey Explorer (WISE) image of the Milky Way bulge, produced by downsampling the publicly available “unWISE” coadds. The WISE image of the Milky Way bulge shows that the X-shaped nature of the Milky Way bulge is self-evident and irrefutable. The X-shape morphology of the bulge in itself and the fraction of bulge stars that comprise orbits within this structure has important implications for the formation history of the Milky Way, and, given the ubiquity of boxy X-shaped bulges, spiral galaxies in general.