THE SAGITTARIUS STREAMS IN THE SOUTHERN GALACTIC HEMISPHERE
THE SAGITTARIUS STREAMS IN THE SOUTHERN GALACTIC HEMISPHERE
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DOI：
10.1088/0004-637x/750/1/80
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发表时间：
2011-11
期刊：
影响因子：
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通讯作者：
Sergey E. Koposov;V. Belokurov;N. Evans;G. Gilmore;M. Gieles;M. Irwin;G. Lewis;M. Niederste-Ostholt-M.-Niederst
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作者：
Sergey E. Koposov;V. Belokurov;N. Evans;G. Gilmore;M. Gieles;M. Irwin;G. Lewis;M. Niederste-Ostholt-M.-Niederst
利用斯隆数字巡天第8版数据分析了银河系南半球射手座气流的结构。与射手座潮汐轨道平行，但在∼10°之外，还有另一条更微弱、更缺乏金属的气流。我们提供的证据表明，这两个流遵循相似的距离梯度，但具有不同的形态特征和恒星种群。与较暗的溪流相比，较亮的溪流范围更广，包含更多富含金属的恒星，具有更丰富的颜色-星等图，具有多个转折和一个突出的红色团块。根据结构特征和恒星群混合，流态类似于北方的“分叉”。在南银河帽地区，有来自穿过人马座溪流的鲸鱼溪流的重叠潮汐碎片。利用光度和光谱数据，我们发现蓝色散星群主要属于人马座，蓝色水平分支恒星主要属于这一混乱位置的鲸鱼座流星。
The structure of the Sagittarius stream in the southern Galactic hemisphere is analyzed with the Sloan Digital Sky Survey Data Release 8. Parallel to the Sagittarius tidal track, but ∼10° away, there is another fainter and more metal-poor stream. We provide evidence that the two streams follow similar distance gradients but have distinct morphological properties and stellar populations. The brighter stream is broader, contains more metal-rich stars, and has a richer color–magnitude diagram with multiple turnoffs and a prominent red clump as compared to the fainter stream. Based on the structural properties and the stellar population mix, the stream configuration is similar to the Northern “bifurcation.” In the region of the South Galactic Cap, there is overlapping tidal debris from the Cetus stream, which crosses the Sagittarius stream. Using both photometric and spectroscopic data, we show that the blue straggler population belongs mainly to Sagittarius and the blue horizontal branch stars belong mainly to the Cetus stream in this confused location in the halo.