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arXiv 2012.09911astro-ph.GA
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LSB星系中的异常恒星星族

Anomalous Stellar Populations in LSB Galaxies

James Schombert, Stacy McGaugh

摘要:

我们提出了新的HST WFC 3近红外观测的CMD的两个LSB星系,F575-3和F615-1,值得注意的是没有目前的恒星形成的基础上缺乏H $α$发射。解决了近红外CMD的关键特征,如红巨星分支(RGB),渐近巨星分支(AGB)区域和蓝色主序列(bMS)的顶部。F575-3在文献中的所有CMD中具有最蓝的RGB,表明平均金属丰度极低。F615-1有着异常宽的RGB和AGB序列,表明它有多个由贫金属气体(可能是下落物质)形成的恒星。这两个星系都有一个不寻常的恒星群体,红色的RGB和较低的光度比典型的AGB恒星。这些恒星有正常的光学颜色,但有异常的近红外颜色。我们认为,这一人口的恒星可能类似于当地特有的恒星,如Be星与强大的近红外线过剩,由于周围的磁盘的热气体。

英文摘要:

We present new HST WFC3 near-IR observations of the CMD's in two LSB galaxies, F575-3 and F615-1, notable for having no current star formation based on a lack of H$α$ emission. Key features of the near-IR CMD's are resolved, such as the red giant branch (RGB), the asymptotic giant branch (AGB) region and the top of the blue main sequence (bMS). F575-3 has the bluest RGB of any CMD in the literature, indicating an extremely low mean metallicity. F615-1 has unusually wide RGB and AGB sequences suggesting multiple episodes of star formation from metal-poor gas, possibly infalling material. Both galaxies have an unusual population of stars to the red of the RGB and lower in luminosity than typical AGB stars. These stars have normal optical colors but abnormal near-IR colors. We suggest that this population of stars might be analogous to local peculiar stars like Be stars with strong near-IR excesses owing to a surrounding disk of hot gas.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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