论文标题
Wiyn Open Cluster研究LXXX：HDI CCD $ UBVRI $ of旧开放群集NGC 7142的光度法和与M67的比较
WIYN Open Cluster Study LXXX: HDI CCD $UBVRI$ Photometry of the Old Open Cluster NGC 7142 and Comparison to M67
论文作者
论文摘要
我们在$ 0.5 ^\ circole \ times0.5 ^\ circ $ field the NGC 7142的方向上呈现$ ubvri $的光度法，在$ 0.5 ^\ times0.5 ^\ circ $ field中，在WIYN 0.9-meter望远镜上使用半学位成像器（HDI）进行，以提高该集群基本参数的知识。我们的光度法跨越$ u $，10.6-22.0 mag in $ b $，10.0-21.8 mag in $ v $，9.2-20.7 mag in $ r $，$ r $和8.5-19.9 mag in $ i $ $ i $。使用颜色彩色图，使用包括$ u $的所有四种颜色组合，而不是$ b-v $，我们得出了群集的变红金属关系，首选值$ e（b-v $）= 0.338 $ \ pm $ 0.031 $ 0.031 MAG的MAG，用于主序列的左派和[0.0 $ pm pm pm pm \ pm \ pm \ pm \ pm \ pm \ pm \ pm \ pm \ fe/h hy = 0.0 $ 0.0 n. 0.0 n. 0.0 n. 0.0 cluster已经采用了一个未经修复的参考群集，Cardelli的灭绝关系，并假定了Yonsei-Yale（$ Y^2 $）等速线的金属依赖性。将我们的数据与$ Y ^2 $等级的比较中的多种颜色量图（CMDS）产生距离金属性和年龄金属关系，首选值为$ M-m \ = \ = \ = \ 12.65 \ \ \ \ \ \ pm \ pm \ 0.23 $ mag and age = $ 4.0 ^$ 4.0 ^{ - 0.7 ^{ - 0.7} { - 0.7} { - 0.7} { - 0.7} $ 1.3} $ 1.3} $ 1.3}。 Re-evaluation of the parameters of M67 using Stetson's $UBVI$ photometry yields [Fe/H] = -0.02 $\pm$ 0.05 dex, $E(B-V$) = 0.04 $\pm$ 0.01 mag, $m-M$ = 9.75 $\pm$ 0.03 mag, and age = 3.85 $\pm$ 0.17 Gyr;因此，我们发现两个簇的金属性和年龄是无法区分的。半独立的分析采用了M67的参数，并在六个CMD中转移了两个簇的基准，直到它们匹配强烈证实上述值。对于NGC 7142和48 $ \ pm $ 15 $μ$，对于M67，我们推断的视差和Gaia DR2值之间的差异为$ 87 \\ pm \ 60 $ $ $ $ $。
We present $UBVRI$ photometry of 8702 stars in a $0.5 ^\circ\times0.5 ^\circ$ field in the direction of NGC 7142, taken with the Half Degree Imager (HDI) at the WIYN 0.9-meter telescope, to improve knowledge of this cluster's basic parameters. Our photometry spans the ranges 10.6 - 20.4 mag in $U$, 10.6 - 22.0 mag in $B$, 10.0 - 21.8 mag in $V$, 9.2 - 20.7 mag in $R$, and 8.5 - 19.9 mag in $I$. Using color-color diagrams that employ all four color combinations that include $U$, versus $B-V$, we derive a reddening-metallicity relation for the cluster, with preferred values $E(B-V$) = 0.338 $\pm$ 0.031 mag for the left-edge fiducial of the main sequence and [Fe/H] = 0.0 $\pm$ 0.1 dex, where the Hyades cluster has been used as an unreddened reference cluster, the extinction relations of Cardelli have been employed, and the metallicity dependence of the Yonsei-Yale ($Y^2$) isochrones has been assumed. Comparison of our data to the $Y^2$ isochrones in multiple color-magnitude diagrams (CMDs) yields distance-metallicity and age-metallicity relations, with preferred values of $m-M\ =\ 12.65\ \pm\ 0.23$ mag and age = $4.0 ^{-0.7}_{+1.3}$ Gyr. Re-evaluation of the parameters of M67 using Stetson's $UBVI$ photometry yields [Fe/H] = -0.02 $\pm$ 0.05 dex, $E(B-V$) = 0.04 $\pm$ 0.01 mag, $m-M$ = 9.75 $\pm$ 0.03 mag, and age = 3.85 $\pm$ 0.17 Gyr; we thus find the metallicity and age of the two clusters to be indistinguishable. A semi-independent analysis adopting the parameters of M67 and shifting the fiducials of the two clusters in six CMDs until they match strongly corroborates the values listed above. The differences between our inferred parallaxes and the Gaia DR2 values are $87\ \pm\ 60$ $μ$as for NGC 7142 and 48 $\pm$ 15 $μ$as for M67, consistent with previous studies.
