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首页> 外文期刊>The Astrophysical journal >Improved Searches for H I in Three Dwarf Spheroidal Galaxies
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Improved Searches for H I in Three Dwarf Spheroidal Galaxies

机译:在三个矮球状星系中对H I的改进搜索

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摘要

Previous searches for H I in our Galaxy's dwarf spheroidal companions have not been complete enough to settle the question of whether or not these galaxies have H I, especially in their outer parts. We present VLA observations of three dwarf spheroidals: Fornax, Leo II, and Draco, all of which have known stellar velocities. The new data show no H I emission or absorption. Column density limits in emission are 4 × 1018 to 7 × 1018 cm-2 in the centers of the galaxies. The importance of the new observations is that they cover larger areas than previous searches and are less plagued by confusion with foreground (Galactic) H I. The apparent absence of neutral gas in the Fornax dwarf spheroidal is especially puzzling, because recent photometry shows evidence of stars only 108 years old. We discuss whether the VLA observations could have missed significant amounts of H I.
机译:先前在银河系的矮球形伴星中搜索H I的过程还不够完善,无法解决这些星系是否具有H I的问题,尤其是在它们的外部。我们介绍了VLA对三个矮球体的观测:Fornax,Leo II和Draco,它们都具有恒星速度。新数据表明没有H I发射或吸收。在星系中心,发射的柱密度极限为4×1018至7×1018 cm-2。新观测的重要性在于,与以前的搜索相比,它们覆盖的区域更大,并且与前景(银河系)H I的混淆较少受到困扰。Fornax矮球体中明显没有中性气体,这尤其令人困惑,因为最近的光度法显示了星星只有108岁。我们讨论了VLA观察是否可能遗漏了大量的HI。

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