Evidence of an asymmetrical Keplerian disk in the Brγ and He I emission lines around the Be star HD 110432

Context. HD 110432 was classified as a gamma Cas X-ray analog since it has similar peculiar X-ray and optical characteristics, i.e. a hard-thermal X-ray variable emission and an optical spectrum affected by an extensive disk. It might be a Be star harboring an accreting white dwarf or that the X-rays may come from an interaction between the surface of the star and its disk. Aims. To investigate the disk around this Be star we used the VLTI/AMBER instrument, which combines high spectral (R = 12 000) and high spatial (theta(min) = 4 mas) resolutions. Methods. We constrain the geometry and kinematics of its circumstellar disk from the highest spatial resolution ever achieved on this star. Results. We obtain a disk extension in the Br gamma line of 10.2 D-star and 7.8 D-star in the He I line at 2.05 mu m assuming a Gaussian disk model. The disk is clearly following a Keplerian rotation. We obtained an inclination angle of 55 degrees, and the star is a nearly critical rotator with V-rot/V-c = 1.00 +/- 0.2. This inclination is greater than the value found for gamma Cas (about 42 degrees), and is consistent with the inference from optical Fe II emission profiles that the inclination should be more than the gamma Cas value. In the near-IR continuum, the disk of HD 110432 is 3 times larger than gamma Cas's disk. We have no direct evidence of a companion around HD 110432, but it seems that we have a clear signature for disk inhomogeneities as detected for zeta Tau. This asymmetrical disk detection may be interpreted within the one-armed oscillation viscous disk framework. Another finding is that the disk size in the near-IR is similar to other Be stars with different spectral types and thus may be independent of the stellar parameters, as found for classical Be stars.