The first orbital solution for the massive colliding-wind binary HD 93162 (≡WR 25)
Departamento de Física, Universidad de La Serena, Benavente 980, La Serena, Chile e-mail: email@example.com
2 Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, 17, 4000, Liège (Sart Tilman), Belgium e-mail: firstname.lastname@example.org
3 Las Campanas Observatory, The Carnegie Observatories, Casilla 601, La Serena, Chile e-mail: email@example.com
4 Facultad de Ciencias Astronómicas y Geofísicas, Universidad de La Plata, Paseo del Bosque / , 1900, La Plata, Argentina e-mail: firstname.lastname@example.org
5 European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: email@example.com
Accepted: 25 August 2006
Context.Since the discovery, with the EINSTEIN satellite, of strong X-ray emission associated with HD 93162 (≡WR 25), this object has been predicted to be a colliding-wind binary system. However, radial-velocity variations that would prove the suspected binary nature have yet to be found.
Aims.We spectroscopically monitored this object to investigate its possible variability to address this discordance.
Methods.We compiled the largest available radial-velocity data set for this star to look for variations that might be due to binary motion. We derived radial velocities from spectroscopic data acquired mainly between 1994 and 2006, and searched these radial velocities for periodicities using different numerical methods.
Results.For the first time, periodic radial-velocity variations are detected. Our analysis definitively shows that the Wolf-Rayet star WR 25 is an eccentric binary system with a probable period of about 208 days.
Key words: stars: binaries: spectroscopic / stars: Wolf-Rayet / stars: individual: HD 93162
© ESO, 2006