The Structure of the Young Stellar Outflows Revealed by High Angular Resolution [Fe II] λ 1.644 μ m Spectroscopy

Abstract

We introduce results of the [Fe ii] λ1.644 μm spectroscopic observations toward the outflows emanating from L1551 IRS 5, DG Tau, HL Tau, and RW Aur. We resolved the region within ~±140 AU (< ±1^′′) from their driving sources with an angular resolution up to $0\rlap.^{''}16$ achieved with the Adaptive Optics System of Subaru Telescope. We detected two distinct velocity components separated in space and velocity for all the objects. The high velocity components (HVCs) show the radial velocities |V|>250 km s^–1 and is extended, while the low velocity components (LVCs) have their peak velocities of 80<|V|<150 km s^–1 and is located near the driving sources. These velocities are consistent with the interpretation that the HVCs are launched from the star surface or its vicinity while the LVCs are accelerated near the inner edges of their accreting disks. We demonstrate that the [Fe ii] spectroscopy at high spatial and velocity resolutions is a powerful tool to study the outflow mechanisms from YSOs with large extinctions.