ABSTRACT. We present long-slit spectroscopy and spectroastrometry of He I 1.083 μm emission in the T Tauri star DG Tauri. We identify three components in the He I feature: (1) a blueshifted emission component at v -200 km s^-1, (2) a bright emission component at zero velocity with a FWZI of ~500 km s^-1, and (3) a blueshifted absorption feature at velocities between -250 and -500 km s^-1. The position and velocity of the blueshifted He I emission coincide with a high-velocity component of the [Fe II] 1.257 μm emission, which arises from a jet within an arcsecond of the star. The presence of such a high-excitation line (with an excitation energy of ~20 eV) within the jet supports the scenario of shock heating. The bright He I component does not show any spatial extension, and it is likely to arise from magnetospheric accretion columns. The blueshifted absorption shows greater velocities than that in Hα, suggesting that these absorption features arise from the accelerating wind close to the star.

Subject headings: accretion, accretion disks; line: formation; stars: individual (DG Tauri); stars: pre-main sequence; ISM: jets and outflows

^* Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Print publication: Issue 1 (2002 March 20)
Received 2002 January 15, accepted for publication 2002 February 15
Published 2002 February 22