An asymmetry detected in the disk ofκ CMa ⋆ with the VLTI/AMBER

Aims. We study the geometry and kinematics of the circumstellar environment of the Be starκ CMa in the Brγ emission line and its nearby continuum. Methods. We use the VLTI/AMBER instrument operating in the K band which provides a spatial resolution of about 6 mas with a spectral resolution of 1500 to study the kinematics within the disk and to infer its rotation law. In order to obtain more kinematic al constraints we also use an high spectral resolution Paβ line profile obtain in December 2005 at the Observatorio do Pi co do Dios, Brazil and we compile V/R line profile variations and spectral energy distribution data po ints from the literature. Results. Using differential visibilities and differential phases across the Brγ line we detect an asymmetry in the disk. Moreover, we found thatκ CMa seems diffi cult to fit within the classical scenario for Be stars, illust rated recently byα Arae observations, i.e. a fast rotating B star close to its breakup velocity surrounded by a Keplerian circumstellar disk with an enhanced polar wind. Finally we discuss the possibility for κ CMa to be a critical rotator with a Keplerian rotating disk and try to see if the detected asymmetry can be interpreted within the ”one-armed” viscous disk framework.