Magnetospheric accretion in the intermediate-mass T Tauri Star HQ Tau

International audienceMagnetospheric accretion is a main interaction process between Classical T Tauri stars (CTTSs) and their inner disk. Understanding this process is therefore crucial to characterize star-disk interactions. We investigate the photometric and spectroscopic variability of HQ Tau, a CTTS of 1.8 M_⊙ and 2.7 R_⊙, from Kepler K2 light curve and a series of ESPaDOnS spectra obtained at the Canada-France-Hawaii Telescope. Balmer line profiles exhibit periodic variability, at the stellar rotation period, with high velocity redshifted absorptions appearing (Inverse P Cygni Profile - IPC). The radial velocity shows a modulation at the stellar rotation period too, but is not consistent with the time of appearance of the IPC. We therefore ascribed the radial velocity modulation to a cold spot and the IPC to the accretion column. From the spectropolarimetric analysis of the ESPaDOnS spectra , we also measure a mean longitudinal magnetic field with a maximum intensity of 430 G, which is modulated by stellar rotation. The maximum is consistent with the IPC, we deduce that the mean longitudinal magnetic field is modulated by the hot spot thus corresponds to the footprint of the magnetic pole at the stellar surface. Preliminary results of this study appear to be consistent with what is expected from magnetospheric accretion onto a global dipolar magnetic field in the intermediate-mass T Tauri star HQ Tau