CURious Variables Experiment (CURVE). CCD Photometry and Variable Stars in the field of open cluster NGC 637

Abstract

We present VI photometry for the open cluster NGC 637 which is located in the Cassiopeia region. Morphology of cluster color-magnitude diagram indicates that it is a young object with age of a few million years. The apparent distance modulus of the cluster is 13.9<(m-M)_V<14.3, while reddening is 0.69<E(V-I)<0.73. We estimated the heliocentric distance as 2.6<d<3.3 kpc. We also report the identification of two variable stars in NGC 637. One of the variables is a non-radial pulsating beta Cep-type star. Other one is a likely ellipsoidal variable, however its pulsating nature can not be excluded.