A deep UBVRI CCD photometry study of the open clusters Tr 1 and Be 11

Abstract

We present deep UBVRI charge-coupled device (CCD) photometry for the young open star cluster Tr 1 and Be 11. the CCD data for Be 11 are obtained for the first time. The sample consists of ~1500 stars reaching down to V ~ 21 mag. Analysis of the radial distribution of the stellar surface density indicates that radius values for Tr 1 and Be 11 are 2.3 and 1.5 pc, respectively. The interstellar extinction across the face of the imaged cluster region seems to be non-uniform with a mean value of E(B-V) = 0.60±0.05 and 0.95±0.05 mag for Tr 1 and Be 11, respectively. A random positional variation of E(B-V) is present in both the clusters. In the cluster Be 11, the reason for the random positional variation may be the apparent association of the H II region (S 213). The 2MASS JHK data in combination with the optical data in the cluster Be 11 yield E(J-K) 0.40±0.20 mag and E(V-K)- 2.20±0.20 mag. Colour excess diagrams indicate a normal interstellar extinction law in the direction of the cluster Be 11.