Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars

Important diagnostics of the star/circumstellar interaction region of Herbig Ae/Be stars are accessible by examining the temporal behavior of the near-IR spectral lines He I λ10830 and Paschen gamma. We reduced and analyzed 30 spectra of the strongly magnetic Herbig Ae star HD101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). We found that the temporal behavior of these diagnostic lines in the near-infrared spectra can be explained by rotational modulation of line profiles generated by accreting gas with a period P = 20.53d. This period is about half of the magnetic rotation period P = 42.76d previously determined from measurements of the mean longitudinal magnetic field. Our finding indicates that the accreted matter falls onto the star in regions close to the magnetic poles intersecting the line-of-sight twice during the rotation cycle. The results of our study clearly demonstrate the power of such an analysis to diagnose the physical properties of accretion flows onto pre-main sequence stars