Leo I - The youngest Milky Way dwarf spheroidal galaxy?
Leo I - The youngest Milky Way dwarf spheroidal galaxy?
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狮子座一号 - 最年轻的银河系矮球状星系？
DOI：
10.1086/116736
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
M. Ruiz
中科院分区：
文献类型：
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作者：
M. Lee;W. Freedman;M. Mateo;I. Thompson;M. Roth;M. Ruiz
我们获得了银河系中已知最远的卫星--狮子座I矮椭球星系（dSph）中16000颗恒星的深CCD测光结果。由此产生的狮子座I的色星等图（CMD）揭示了几个引人注目的特征。(1)有一个定义明确的红巨星分支（RGB），它非常蓝，比所有其他矮dSphs和银河系球状星团都有一个更平坦的斜坡。RGB的尖端位于I TRGB =18.25±0.10等和（V-I）TRGB =1.43±0.02等。（2）与所有其他已知的dSphs不同，Leo I没有明显的水平分支;但是，它确实显示了一个强大的红巨星团，其V = 22.4等和（V-I）= 0.8等。（3）Leo I的CMD显示了1050个异常造父变星候选者
We have obtained deep CCD photometry of ∼16 000 stars in the Leo I dwarf spheroidal galaxy (dSph), the most distant known satellite of the Milky Way Galaxy. The resulting color-magnitude diagrams (CMDs) of Leo I reveal several striking features. (1) There is a well-defined red giant branch (RGB) which is very blue and has a flatter slope than all other dwarf dSphs and Galactic globular clusters. The tip of the RGB is at I TRGB =18.25±0.10 mag and (V−I) TRGB =1.43±0.02 mag. (2) Unlike all of the other known dSphs; Leo I has no obvious horizontal branch; however, it does show a strong clump of red giants at V≃22.4 mag and (V−I)≃0.8 mag. (3) The CMD of Leo I shows ∼50 anomalous Cepheid candidates