Abstract
Aims.Our goal was to improve the fundamental parameters of the massive close double-lined eclipsing B2.5V+B2.5V binary CV Velorum. Methods: We gathered new high-resolution échelle spectroscopy on 13 almost consecutive nights covering two orbits. We computed a simultaneous solution to all the available high-quality radial-velocity and light data with the latest version of the Wilson-Deviney code. Results: We obtained the following values for the physical parameters: M<SUB>1</SUB> = 6.066(74)~M_o, M<SUB>2</SUB> = 5.972(70)~M_o, R<SUB>1</SUB> = 4.126(24)~R_o, R<SUB>2</SUB> = 3.908(27)~R_o, log L<SUB>1</SUB> = 3.20(5)~L_o, and log L<SUB>2</SUB> = 3.14(5)~L_o. The quoted errors contain a realistic estimate of systematic uncertainties mainly stemming from the effective temperature estimation. We derived abundances for both components and found them to be compatible with those of B stars in the solar neighbourhood. We discovered low-amplitude periodic line-profile variations with the orbital frequency for both components. Their interpretation requires new data with a longer time span. The primary rotates subsynchronously while the secondary's v sin i and radius are compatible with synchronous rotation. We provide an update of the empirical mass-luminosity relation for main-sequence B stars which can be used for statistical predictions of masses or luminosities. Based on spectroscopic observations gathered with the CORALIE spectrograph mounted on the 1.2 m Euler telescope at La Silla, Chile.
