Spectroscopic study of the open cluster Blanco 1J. F. González and H. Levato
Instituto de Ciencias Astronómicas, de la Tierra y del Espacio, Casilla 467, 5400 San Juan, Argentina
Received 26 June 2009 / Accepted 17 August 2009
Aims. As a part of our program on binaries in open clusters, we present a spectroscopic study of the bright stars of Blanco 1 aimed at detecting and characterizing spectroscopic binaries.
Methods. Forty five stars previously mentioned as cluster candidates, plus another 24 stars in a wider region around the cluster were observed repeatedly during 6 years, with a spectral resolving power 13 300. Radial velocities were measured by cross-correlations.
Results. We obtained a mean cluster velocity of 6.2 0.3 km s-1 and determined kinematic membership. Eleven spectroscopic binaries were detected, and orbital solutions are presented for eight of them. Six binaries are confirmed to be members of the cluster. All of them are single-lined spectroscopic systems with periods in the range 1.9-1380 days. Considering all suspected binaries, the cluster binary frequency amounts to about 50%.
Key words: open clusters and associations: individual: Blanco 1 -- binaries: spectroscopic -- techniques: radial velocities
© ESO 2009