Examining Magnetospheric Accretion in Herbig Ae/Be Stars Through Near-infrared Spectroscopic Signatures

摘要

Models of magnetically driven accretion and outflows reproduce many observational properties of TTauri stars. For the more massive Herbig Ae/Be stars, the corresponding picture is not well established. Nonetheless, it is expected that accretion flows in pre-main-sequence stars are guided from the circumstellar disk to stellar regions of high latitude along the magnetic field lines inside a magnetosphere. Using near-infrared multi-epoch spectroscopic data obtained with ISAAC, CRIRES, and X-shooter on the VLT, we examined magnetospheric accretion in the two Herbig Ae stars HD 101412 and HD 104237. Spectroscopic signatures in Hei 10 830 and Pay, two near-infrared lines that are formed in a Herbig star's accretion region, show temporal modulation in both objects. For HD 101412, this modulation is governed by its rotation period, which we could recover from the data. We could show that our spectroscopic observations can be explained within the magnetic geometry that we established earlier from magnetic field measurements. For HD 104237, we struggled to clearly identify a rotation period. We intend to apply this method to a larger sample of Herbig Ae/Be stars to learn more about their rotation properties and the accretion mechanisms at work.