The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
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DOI：
10.1086/338983
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发表时间：
2001-11
期刊：
影响因子：
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通讯作者：
H. Newberg;B. Yanny;C. Rockosi;E. Grebel;H. Rix;J. Brinkmann;I. Csabai;G. Hennessy;R. Hindsley-R.-Hi
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文献类型：
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作者：
H. Newberg;B. Yanny;C. Rockosi;E. Grebel;H. Rix;J. Brinkmann;I. Csabai;G. Hennessy;R. Hindsley-R.-Hi
我们在银河系中发现了新的结构，从sloan数字天空调查中检测到的五百万颗恒星的颜色和尺寸在两个先前发现的潮汐破坏结构中的恒星的图（CMD）。在一个方向上，我们甚至能够从散布在110 deg2的天空上的恒星中检测到一团红色的恒星。另外五个恒星的过度度。银河系比厚型恒星明显蓝色，但恒星比幂律球形的预测更接近银河系。结构可能是银河系的新矮人卫星，隐藏在银河平面上，在潮湿的过程中，它可能是磁盘状的一部分。恒星的分布是金属势的，比例高约2 kpc，比例长度约为10 kpc。任何已知的银河系结构。球体必须非常扁平，轴向比= 0.5。
We identify new structures in the halo of the Milky Way from positions, colors, and magnitudes of five million stars detected in the Sloan Digital Sky Survey. Most of these stars are within 1.°26 of the celestial equator. We present color-magnitude diagrams (CMDs) for stars in two previously discovered, tidally disrupted structures. The CMDs and turnoff colors are consistent with those of the Sagittarius dwarf galaxy, as had been predicted. In one direction, we are even able to detect a clump of red stars, similar to that of the Sagittarius dwarf, from stars spread across 110 deg2 of sky. Focusing on stars with the colors of F turnoff objects, we identify at least five additional overdensities of stars. Four of these may be pieces of the same halo structure, which would cover a region of the sky at least 40° in diameter, at a distance of 11 kpc from the Sun (18 kpc from the center of the Galaxy). The turnoff is significantly bluer than that of thick-disk stars, yet the stars lie closer to the Galactic plane than a power-law spheroid predicts. We suggest two models to explain this new structure. One possibility is that this new structure could be a new dwarf satellite of the Milky Way, hidden in the Galactic plane and in the process of being tidally disrupted. The other possibility is that it could be part of a disklike distribution of stars which is metal-poor, with a scale height of approximately 2 kpc and a scale length of approximately 10 kpc. The fifth overdensity, which is 20 kpc away, is some distance from the Sagittarius dwarf streamer orbit and is not associated with any known Galactic structure. We have tentatively identified a sixth overdensity in the halo. If this sixth structure is instead part of a smooth distribution of halo stars (the spheroid), then the spheroid must be very flattened, with axial ratio q = 0.5. It is likely that there are many smaller streams of stars in the Galactic halo.