Vol 18, No 3

New open cluster candidates discovered in the XSTPS-GAC survey

Jin-Cheng Guo, Hua-Wei Zhang, Hui-Hua Zhang, Xiao-Wei Liu, Hai-Bo Yuan, Yang Huang, Song Wang, Li Chen, Hai-Bin Zhao, Ji-Feng Liu, Bing-Qiu Chen, Mao-Sheng Xiang, Zhi-Jia Tian, Zhi-Ying Huo, Chun Wang


Abstract The Xuyi Schmidt Telescope Photometric Survey of the Galactic Anti-center (XSTPS-GAC) is a photometric sky survey that covers nearly 6 000 deg2 towards the Galactic Anti-center (GAC) in the g, r, i bands. Half of its survey field is located on the Galactic Anti-center disk, which makes XSTPS-GAC highly suitable to search for new open clusters in the GAC region. In this paper, we report new open cluster candidates discovered in this survey, as well as properties of these open cluster candidates, such as age, distance and reddening, derived by isochrone fitting in the color-magnitude diagram (CMD). These open cluster candidates are stellar density peaks detected in the star density maps by applying the method from Koposov et al. Each candidate is inspected in terms of its true color image composed from three XSTPS-GAC band images. Then its CMD is checked, in order to identify whether the central region stars have a clear isochrone-like trend differing from background stars. The parameters derived from isochrone fitting for these candidates are mainly based on three band photometry of XSTPS-GAC. Moreover, when these new candidates are able to be seen clearly in 2MASS data, their parameters are also derived based on the 2MASS (J − H, J) CMD. There are a total of 320 known open clusters rediscovered and 24 new open cluster candidates discovered in this work. Furthermore, the parameters of these new candidates, as well as another 11 previously known open clusters, are properly determined for the first time.


Keywords open clusters and associations: general — Galaxy: structure — methods: data analysis

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