First spectra of the W UMa system V524 Monocerotis^*

European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: tdall@eso.org

Received: 16 May 2004
Accepted: 27 August 2004

Abstract

We present the first high-resolution spectra of the W UMa contact binary V524 Mon. The spectra of the two components are very similar, resembling a G5 and a K0. We find the radial velocities and rotational velocities consistent with corotation. We estimate the radii and the masses and derive a mass ratio . We confirm that V524 Mon is a W-type contact system, likely enclosed in a common convective envelope, as found by [CITE]. We do not find evidence for the expected level of emission in the chromospheric H and K lines, neither Hα, indicating that the magnetic activity is much weaker than expected or that other processes are hampering chromospheric emission.