We present deep CCD photometry ( V ~ 21 mag) in BVR Johnson-Cousin filters supported with 2MASS JHKs data set for the open star cluster NGC 7790. The cluster’s parameters such as reddening, distance, metallicity and age etc… are derived using two color diagrams in optical and near-infrared bands. These parameters are E B-V = 0.512 ± 0.006, E V-R = 0.382 ± 0.005, E J-H = 0.337 ± 0.001 and E J-Ks = 0.505 ± 0.001 mag, the distance modulus ( m - M ) 0 = 12.41 ± 0.001 mag, which gives a distance of 3.035 kpc and the metallicity Z = 0.008. The age obtained by fitting the observed CMDs with Padova isochrones is 63.95 Myr. From the analysis of 2MASS data, the limiting radius of the cluster is found to be 9.7 ± 0.83 arcmin, it reflects that the cluster is a compact cluster. The dynamical relaxation time of NGC 7790 is also determined and found to be 0.17 of its age, which means that the cluster is dynamically relaxed. Moreover, luminosity and mass functions are also investigated.

中文翻译：

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年轻疏散星团NGC 7790的新光学和红外光度学研究

我们在 BVR Johnson-Cousin 滤光片中展示了深度 CCD 光度测量（V ~ 21 mag），该滤光片支持疏散星团 NGC 7790 的 2MASS JHKs 数据集。该星团的参数，如变红、距离、金属丰度和年龄等……是使用两种颜色得出的光学和近红外波段的图表。这些参数是 E BV = 0.512 ± 0.006、E VR = 0.382 ± 0.005、E JH = 0.337 ± 0.001 和 E J-Ks = 0.505 ± 0.001 mag，距离模量 (m - M) 0 = 10.001 mag给出 3.035 kpc 的距离和金属度 Z = 0.008。通过将观测到的 CMD 与 Padova 等时线拟合得到的年龄为 63.95 Myr。从2MASS数据分析，发现该星团的极限半径为9.7±0.83 arcmin，反映该星团是一个致密星团。NGC 7790 的动态弛豫时间也被确定并发现为 0。17 的年龄，这意味着集群是动态放松的。此外，还研究了光度和质量函数。