The orbital solution and dynamical masses of the binary system V* PX Virginis

Abstract

Abstract V* PX Vir is a nearby single-lined spectroscopic binary with the primary being a variable of a BY Dra-type star. It has a period of ∼216 d and the components of the system are two low-mass pre-main-sequence stars. By a simultaneous least-squares fit to the radial velocities, the relative positions, and the revised Hipparcos intermediate astrometric data, the complete orbital solution is derived and the precision is improved significantly. In addition, the Hipparcos parallax is revised as 46.06±0.69 mas. Taking advantage of the resulting orbital elements and parallax, the component masses are calculated to be 0.74±0.06 M⊙ and 0.47±0.02 M⊙, respectively. The absolute magnitudes in the K and H bands are determined as 4.32±0.14, 4.42±0.03 for the primary and 5.63±0.46, 6.08±0.03 for the secondary, respectively. According to the derived physical parameters, the two components of the system lie very close to the same isochrone age 0.1–0.14 Gyr by comparison with pre-main-sequence evolution tracks.