论文标题
从Gaia Edr3测得的Omega Centauri的视差以及红色巨型分支的尖端的直接几何校准和哈勃常数
The Parallax of Omega Centauri Measured from Gaia EDR3 and a Direct, Geometric Calibration of the Tip of the Red Giant Branch and the Hubble Constant
论文作者
论文摘要
我们使用来自ESA Gaia Mission早期数据版本3（EDR3）的数据来测量$ω$ CEN的三角视差，这是银河系中最庞大的球形群集的第一个高精度视差测量。我们使用来自EDR3的位置和高质量适当的运动数据的组合来识别超过100,000个集群成员，其中67,000个位于EDR3可视parallaxes最好校准的大小和颜色范围内。我们发现估计的视差是鲁棒的，可以很好地控制群集的颜色标记中的系统学。我们发现$ 0.191 \ pm0.001 $（统计）$ \ pm0.004 $（系统）MAS（2.2 \％总不确定度）的群集的视差为$ 5.24 \ pm0.11 $ kpc。 $ω$ CEN的视差提供了一个独特的机会，可以直接和几何校准红色巨型分支（TRGB）的尖端的发光度，因为它是唯一具有足够质量的群集，可以提供足够的红色巨星，在尖端以下超过100个幅度，以精确的，无用的模型测量。结合尖端和前景银河系的既有和最广泛使用的测量结果，我们发现$ m_ {i，trgb} = - 3.97 \ 3.97 \ pm0.06 $ mag for $ i $ band band luminite in the Blue Edge的亮度。使用$ω$ CEN的GAIA EDR3视差校准的TRGB发光度来校准SNIA的光度，从而使Hubble常数$ H_0 = 72.1 \ pm2.1 \ pm2.0 $ km s $ s $^{ - 1} $ MPC $^{ - 1} $。我们将$ω$ CEN的恒星数据以电子方式提供，并鼓励对此处介绍的结果进行独立的分析。
We use data from the ESA Gaia mission Early Data Release 3 (EDR3) to measure the trigonometric parallax of $ω$ Cen, the first high precision parallax measurement for the most massive globular cluster in the Milky Way. We use a combination of positional and high quality proper motion data from EDR3 to identify over 100,000 cluster members, of which 67,000 are in the magnitude and color range where EDR3 parallaxes are best calibrated. We find the estimated parallax to be robust, demonstrating good control of systematics within the color-magnitude diagram of the cluster. We find a parallax for the cluster of $0.191\pm0.001$ (statistical) $\pm0.004$ (systematic) mas (2.2\% total uncertainty) corresponding to a distance of $5.24\pm0.11$ kpc. The parallax of $ω$ Cen provides a unique opportunity to directly and geometrically calibrate the luminosity of the Tip of the Red Giant Branch (TRGB) because it is the only cluster with sufficient mass to provide enough red giant stars, more than 100 one magnitude below the tip, for a precise, model-free measurement of the tip. Combined with the pre-existing and most widely-used measurements of the tip and foreground Milky Way extinction, we find $M_{I,TRGB}=-3.97\pm0.06$ mag for the $I$-band luminosity of the blue edge. Using the TRGB luminosity calibrated from the Gaia EDR3 parallax of $ω$ Cen to calibrate the luminosity of SNIa results in a value for the Hubble constant of $H_0=72.1\pm2.0$ km s$^{-1}$ Mpc$^{-1}$. We make the data for the stars in $ω$ Cen available electronically and encourage independent analyses of the results presented here.
