论文标题
关于红色团块的颜色金属关系和对麦芽云的红色
On the Color-Metallicity Relation of the Red Clump and the Reddening Toward the Magellanic Clouds
论文作者
论文摘要
朝向大麦芽云（LMC）的零点是一些争议的主题。它的不确定性是通过了解LMC恒星绝对灭绝来衡量的方法的系统误差。为了解决此问题，我们使用了三种不同的方法来校准最广泛使用的度量标准，以预测LMC灭绝，即红色团块的内在颜色，$（v-i）_ {rc，0} $，用于内部$ \ sim $ 3度。第一种方法是在$δ\ rm {[[fe/h]} \大约1.10 $的宽金属范围内，使用47 TUC，太阳能邻域和NGC 6791的宽大金属范围校准Basti等线的颜色zeropoints。 从这些努力中，我们还测量了太阳邻域红色团块的这些属性，（$ v-i $，$ g_ {bp} -k_ {s} $，$ g-k_ {s} $，$ g_ {rp} -k_ {s s} {s} $ m_ {ks} $）$ _ {rc，0} = $（1.02、2.75、2.18、1.52、0.64、0.15、0.15、0.15，$ - $ 0.23，$ - $ 1.63）。第二和第三种方法是将红色团块的颜色与LMC中的Cepheids和RR Lyrae的颜色进行比较。使用这三种方法，我们估计LMC红色团块的内在颜色为$（v-i）_ {rc，0，\ rm {lmc}} = \ {\ {\ {\ of 0.93,0.91 \ of约0.02,0.2,0.89 （v-i）_ {rc，0，\ rm {smc}} = \ {\ oft 0.85,0.84 \ pm 0.02 \} $分别用于小麦芽岩云。我们估计亮度为$ m_ {i，rc，\ rm {lmc}}} = - 0.26 $和$ m_ {i，rc，rc，\ rm {smc}} = - 0.37 $。我们表明，这对用于测量$ H_0 $的麦哲伦云中红色巨型分支的尖端的最新校准具有重要意义。
The zero point of the reddening toward the Large Magellanic Cloud (LMC) has been the subject of some dispute. Its uncertainty propagates as a systematic error for methods which measure the extragalactic distance scale through knowledge of the absolute extinction of LMC stars. In an effort to resolve this issue, we used three different methods to calibrate the most widely-used metric to predict LMC extinction, the intrinsic color of the red clump, $(V-I)_{RC,0}$, for the inner $\sim$3 degrees of that galaxy. The first approach was to empirically calibrate the color zeropoints of the BaSTI isochrones over a wide metallicity range of $Δ\rm{[Fe/H]} \approx 1.10$ using measurements of red clump stars in 47 Tuc, the Solar Neighborhood, and NGC 6791. From these efforts we also measure these properties of the Solar Neighborhood red clump, ($V-I$, $G_{BP}-K_{s}$, $G-K_{s}$, $G_{RP}-K_{s}$, $J-K_{s}$, $H-K_{s}$, $M_{I}$, $M_{Ks}$)$_{RC,0} =$ (1.02, 2.75, 2.18, 1.52, 0.64, 0.15, $-$0.23, $-$1.63). The second and third methods were to compare the observed colors of the red clump to those of Cepheids and RR Lyrae in the LMC. With these three methods, we estimated the intrinsic color of the red clump of the LMC to be $(V-I)_{RC,0,\rm{LMC}} = \{ \approx 0.93,0.91 \pm 0.02,0.89 \pm 0.02\}$ respectively, and similarly using the first and third method we estimated $ (V-I)_{RC,0,\rm{SMC}} = \{\approx 0.85,0.84 \pm 0.02 \}$ respectively for the Small Magellanic Cloud. We estimate the luminosities to be $M_{I,RC,\rm{LMC}}=-0.26$ and $M_{I,RC,\rm{SMC}}=-0.37$. We show that this has important implications for recent calibrations of the tip of the red giant branch in the Magellanic Clouds used to measure $H_0$.
