Sejong Open Cluster Survey (SOS) - IV. The Young Open Clusters NGC 1624 and NGC 1931 Beomdu Lim1,5, Hwankyung Sung2, Michael S. Bessell3, Jinyoung S. Kim4, Hyeonoh Hur2, and Byeong-Gon Park1
[email protected] Received ; accepted Not to appear in Nonlearned J., 45. 1Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348, Korea 2Department of Astronomy and Space Science, Sejong University, 209 Neungdong-ro, arXiv:1502.00105v1 [astro-ph.SR] 31 Jan 2015 Gwangjin-gu, Seoul 143-747, Korea 3Research School of Astronomy and Astrophysics, Australian National University, MSO, Cotter Road, Weston, ACT 2611, Australia 4Steward Observatory, University of Arizona, 933 N. Cherry Ave. Tucson, AZ 85721-0065, USA 5Corresponding author, Korea Research Council of Fundamental Science & Technology Research Fellow –2– ABSTRACT Young open clusters located in the outer Galaxy provide us with an oppor- tunity to study star formation activity in a different environment from the solar neighborhood. We present a UBVI and Hα photometric study of the young open clusters NGC 1624 and NGC 1931 that are situated toward the Galactic anticenter. Various photometric diagrams are used to select the members of the clusters and to determine the fundamental parameters. NGC 1624 and NGC 1931 are, on average, reddened by hE(B − V )i = 0.92 ± 0.05 and 0.74 ± 0.17 mag, respectively. The properties of the reddening toward NGC 1931 indicate an abnormal reddening law (RV,cl = 5.2 ± 0.3). Using the zero-age main se- quence fitting method we confirm that NGC 1624 is 6.0 ± 0.6 kpc away from the Sun, whereas NGC 1931 is at a distance of 2.3 ± 0.2 kpc.