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Bulgarian Journal of Physics
Print: 1310-0157 Online: 1314-2666
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RECOGNIZED BY THE EUROPEAN PHYSICAL SOCIETY 
Bulg. J. Phys. vol.33 no.1 (2006), pp. 68-72
Age Determination of Possible Binary Open Clusters NGC 2383/NGC 2384 and Pismis 6/Pismis 8
V. Kopchev1, G. Petrov1, P. Nedialkov2
1Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko chaussee Blvd, BG-1784 Sofia, Bulgaria
2Department of Astronomy, Sofia University, 5 James Bourcher Blvd, BG-1164 Sofia, Bulgaria
go back1Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko chaussee Blvd, BG-1784 Sofia, Bulgaria
2Department of Astronomy, Sofia University, 5 James Bourcher Blvd, BG-1164 Sofia, Bulgaria
Abstract. Based on 2MASS J and Ks photometry for the open star clusters NGC 2383, NGC 2384, Pismis 6, Pismis 8 and using color magnitude diagrams with isochrones fit, we found an age of log(age) = 8.3 (200 ± 6 Myr) for NGC 2383 and log(age) = 6.9 (8 ± 6 Myr) for NGC 2384. For Pismis 6 and Pismis 8 we adopted a range of log(age) = 6 - 7 (1 - 10 Myr). Because of their similar ages, Pismis 6 and Pismis 8 might have been formed in the same Giant Molecular Cloud, and we conclude they are a good candidate for a binary system. In the case of NGC 2383 and NGC 2384, because of the big age difference found, we conclude that most probably they are born in different environments and are not physically connected.