论文标题
黄色的临时巨型分支星星作为标准蜡烛。 I.银河球状簇中的光度功能的校准
Yellow Post-Asymptotic-Giant-Branch Stars as Standard Candles. I. Calibration of the Luminosity Function in Galactic Globular Clusters
论文作者
论文摘要
我们使用银河系（和LMC）球状簇中低表面重力恒星的调查结果表明，“黄色”的轴突后巨型支流（YPAGB）恒星可能是出色的出色外层次标准蜡烛，它可能是能够与早期型星系产生准确的距离，这些蜡烛可以准确地达到几个百分点。我们表明，球状簇中10个已知YPAGB恒星的平均降压幅度为<mbol> = -3.38 +/- 0.03，该值比最新的后 - 霍森塔尔 - 分支 - 分支 - 分支进化轨迹预测到的值〜0.2 mag亮。更重要的是，我们表明分布中观察到的分散体仅为0.10 mag，即小于单个头孢虫的散射小。我们描述了可以产生如此小的分散体的物理学，并表明，如果人们将调查限制为颜色范围0 <（b-v）0 <0.5，则可以很容易地在最小的污染中轻松地识别出不可变化的YPAGB星的样品。这些恒星的明亮绝对V幅度（<mv> = -3.37）使它们成为旧恒星种群中最明亮的物体和理想种群II标准蜡烛，用于测量〜10 MPC，并具有当前仪器。因此，在M81和雕塑家组中的星系晕halos中进行的哈勃太空望远镜调查可以作为Cepheid和TRGB距离尺度的有效交叉检查。
We use results of a survey for low-surface-gravity stars in Galactic (and LMC) globular clusters to show that "yellow" post-asymptotic-giant-branch (yPAGB) stars are likely to be excellent extragalactic standard candles, capable of producing distances to early-type galaxies that are accurate to a few percent. We show that the mean bolometric magnitude of the 10 known yPAGB stars in globular clusters is <Mbol> = -3.38 +/- 0.03, a value that is ~0.2 mag brighter than that predicted from the latest post-horizontal-branch evolutionary tracks. More importantly, we show that the observed dispersion in the distribution is only 0.10 mag, i.e., smaller than the scatter for individual Cepheids. We describe the physics that can produce such a small dispersion, and show that, if one restricts surveys to the color range 0 < (B-V)0 < 0.5, then samples of non-variable yPAGB stars can be identified quite easily with a minimum of contamination. The bright absolute V magnitudes of these stars (<Mv> = -3.37) make them, by far, the visually brightest objects in old stellar populations and ideal Population II standard candles for measurements out to ~10 Mpc with current instrumentation. A Hubble Space Telescope survey in the halos of galaxies in the M81 and Sculptor groups could therefore serve as an effective cross-check on both the Cepheid and TRGB distance scales.
