WIYN Open Cluster Study LXXX: HDI CCD $UBVRI$ Photometry of the Old Open Cluster NGC 7142 and Comparison to M67

Abstract

We present $UBVRI$ photometry of 8702 stars in a $0.5^{\circ }\times 0.5^{\circ }$ 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 = $4.0_{+1.3}^{-0.7}$ 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 $87\pm 60$ $\mu$as for NGC 7142 and 48 $\pm$ 15 $\mu$as for M67, consistent with previous studies.

20 pages, 15 figures, 6 tables, and accepted in the Astronomical Journal

References in corpus (4)

• The Gaia mission
• Ground-based CCD astrometry with wide field imagers. II. A star catalogue for M67: [email protected] MPG/ESO astrometry, FLAMES@VLT radial velocities
• WIYN Open Cluster Study. LXXV. Testing the Metallicity Dependence of Stellar Lithium Depletion Using Hyades-Aged Clusters. 1. Hyades & Praesepe
• Metallicities for 13 nearby open clusters from high-resolution spectroscopy of dwarf and giant stars. Stellar metallicity, stellar mass, and giant planets

Cited by in corpus (3)

• Determination of dynamical ages of open clusters through the A${}^{+}$ parameter -- I
• A uvbyCaHbeta CCD Analysis of the Open Cluster Standard, M67,and its Relation to NGC 752
• Validation of the Gaia Early Data Release 3 parallax zero-point model with asteroseismology