The intermediate polar cataclysmic variable GK Persei 120 years after the nova explosion: a first dynamical mass study

Abstract

We present a dynamical study of the intermediate polar and dwarf nova cataclysmic variable GK Persei (Nova Persei 1901) based on a multisite optical spectroscopy and R-band photometry campaign. The radial velocity curve of the evolved donor star has a semi-amplitude K2=126.4±0.9kms−1 and an orbital period P=1.996872±0.000009d⁠. We refine the projected rotational velocity of the donor star to vrotsini=52±2kms−1 that, together with K2, provides a donor star to white dwarf mass ratio q = M2/M1 = 0.38 ± 0.03. We also determine the orbital inclination of the system by modelling the phase-folded ellipsoidal light curve and obtain i = 67° ± 5°. The resulting dynamical masses are M1=1.03+0.16−0.11M⊙ and M2=0.39+0.07−0.06M⊙ at 68 per cent confidence level. The white dwarf dynamical mass is compared with estimates obtained by modelling the decline light curve of the 1901 nova event and X-ray spectroscopy. The best matching mass estimates come from the nova light curve models and an X-ray data analysis that uses the ratio between the Alfvén radius in quiescence and during dwarf nova outburst.