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Cepheid variables in the flared outer disk of our galaxy

机译：星系外盘的造父变星

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摘要

Flaring and warping of the disk of the Milky Way have been inferred from observations of atomic hydrogen but stars associated with flaring have not hitherto been reported. In the area beyond the Galactic centre the stars are largely hidden from view by dust, and the kinematic distances of the gas cannot be estimated. Thirty-two possible Cepheid stars (young pulsating variable stars) in the direction of the Galactic bulge were recently identified. With their well-calibrated period-luminosity relationships, Cepheid stars are useful distance indicators. When observations of these stars are made in two colours, so that their distance and reddening can be determined simultaneously, the problems of dust obscuration are minimized. Here we report that five of the candidates are classical Cepheid stars. These five stars are distributed from approximately one to two kiloparsecs above and below the plane of the Galaxy, at radial distances of about 13 to 22 kiloparsecs from the centre. The presence of these relatively young (less than 130 million years old) stars so far from the Galactic plane is puzzling, unless they are in the flared outer disk. If so, they may be associated with the outer molecular arm.
机译：从原子氢的观察可以推断出银河系盘的耀斑和翘曲，但迄今尚未报道与耀斑有关的恒星。在银河系中心以外的区域，恒星在很大程度上被尘埃所掩盖，并且无法估算出气体的运动距离。最近发现了在银河凸起方向上的32个可能的造父变星（年轻的脉动变星）。造父变星具有经过良好校准的周期-光度关系，因此它们是有用的距离指示器。当对这些恒星进行两种颜色的观测时，可以同时确定它们的距离和变红，从而将灰尘遮盖的问题降到最低。在这里，我们报告说有五位候选人是经典造父变星。这五颗恒星分布在银河系平面上方和下方约一到两千帕秒，距中心约13到22千帕秒的径向距离。距离银河系平面如此遥远的这些相对年轻（不到1.3亿年历史）的恒星的存在令人费解，除非它们位于向外张开的外盘中。如果这样，它们可能与外部分子臂相关。

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  • 来源
    《Nature》 |2014年第7500期|342-344|共3页
  • 作者

    Michael W. Feast; John W. Menzies; Noriyuki Matsunaga; Patricia A. Whitelock;

  • 作者单位

    Astrophysics, Cosmology and Gravity Centre, Astronomy Department, University of Cape Town, Rondebosch 7701, South Africa,South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa;

    South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa;

    Department of Astronomy, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;

    Astrophysics, Cosmology and Gravity Centre, Astronomy Department, University of Cape Town, Rondebosch 7701, South Africa,South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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