The Nearby Open Cluster Collinder 140

Abstract

Photoelectric UBV data of 77 stars in the region of Cr 140, as well as β indices of 31 stars and DDO data of one red star, are reported and discussed. In addition, MK spectral types of the four brightest B stars in the region are also given. These data, together with existing radial velocity and proper motion measurements, show that Cr 140 is a real, dynamically stable, open cluster. Twenty-seven stars, including a red giant, appear to be cluster members. The average color excess, due to interstellar reddening, is E (B -V)=0.05 and the true distance modulus was found to be V 0 -M v =7.78. A nuclear age of 2.1 X 107 yr and a lower limit to the contraction age of 2.3 X 107 yr were also obtained for the cluster. Assuming that the metal content of the red giant member is representative of that of the whole cluster, then Cr 140 is slightly metal weak compared to the Hyades.