In this paper, we derived the empirical relationship between stellar surface brightness parameter(F_v) and (V-R_c) colour in Cousins system appropriate to dwarf cepheids. Also theoretical counterpart to this relation has been calculated from model atm...
In this paper, we derived the empirical relationship between stellar surface brightness parameter(F_v) and (V-R_c) colour in Cousins system appropriate to dwarf cepheids. Also theoretical counterpart to this relation has been calculated from model atmospheres. The theoretical relation is in reasonable agreement with the empirical relation but reveals small sensitivities to surface gravity and metallicity. Both relations were used to apply the surface brightness method to estimate the radius of four dwarf cepheids of YZ Boo, AD CMi, XX Cyg, and EH Lib which were observed with V and R band in Cousins photometric system by Kim and Joner (1994). We could obtain the reliable result for AD CMi and it was fund that, for three other variables, there are large phase shifts between angular diameter variation and radial displacements.