On the mass of nova DQ Hercules (1934)

Abstract

Time-resolved high-resolution CCD spectroscopy covering two 4.6-hr orbits of DQ Her are presented. Analysis of the Na I 8183,8195 A absorption doublet yields estimates of the secondary star's projected orbital velocity and rotational broadening. The estimate of the projected orbital velocity is refined using models of the effects of irradiation on the secondary star, producing a final value of 227 +/- 10 km/s. The stellar masses are estimated at M1 = 0.60 +/- 0.07 and M2 = 0.40 +/- 0.05 solar mass.