The semi-detached eclipsing binary system V621 Cen (P = 3.68 d) has been analysed using the Wilson-Devinney program, on the basis of light curves obtained in the GENEVA 7-colour photometric system, and radial velocity curves for both components measured with the cross-correlation technique. The physical and orbital parameters have been determined through a self-consistent simultaneous solution of the photometric and radial velocity curves. The effective temperature of the primary component has been determined from the photometric analysis, T eff 1 ΒΌ 15; 600 AE 800 K.
The absolute elements of the components are for the primary (mass gainer), with the value of T eff 1 fixed, M 1 = 6.10 Β± 0.10M x , R 1 = 4.58 Β± 0.01R x , M bol 1 ΒΌ Γ2:83 AE 0:01, and for the secondary (mass loser), M 2 = 2.09 Β± 0.04M x , R 2 = 5.87 Β± 0.01R x , M bol 2 ΒΌ Γ0:86 AE 0:01, T eff 2 ΒΌ 8750 AE 20 K. The semi-major axis A of the relative orbit is 20.20 Β± 0.12R x . The estimated spectral types of the components are about B3/4 V (primary) and A0/1III (secondary). The equatorial rotational velocity of the primary is 63 km s Γ1 . The distance to V621 Cen is evaluated to 1550 Β± 140 pc, and the colour excess E[B2 Γ V1] to 0.270 Β± 0.045.