HIGH ANGULAR RESOLUTION [Fe II] λ1.644 μ SPECTROSCOPY OF YSOS WITH SUBARU TELESCOPE

Abstract

We present results of the velocity-resolved spectroscopy of the [Fe II] <TEX>$\lambda$</TEX>1.644<TEX>${\mu}m$</TEX> emission toward outflow sources with the Subaru Telescope at the angular resolution of 0.apos;16 <TEX>${\~}$</TEX> 0.apos;5 arcseconds. The observed sources are L1551 IRS 5, DG Tau, HL Tau and RW Aur, which are located in the Taurus-Aurigae Molecular Cloud, one of the closest star forming regions (0.apos;1 = 14 AU). We were able to resolve outflow structure in the vicinity of the sources at a scale of a few tens of AU. The position-velocity diagram of each object shows two velocity components: the high velocity component (HVC: 200 - 400 km <TEX>$s^{-l}$</TEX>) and the low velocity component (LVC: 50 - 150 km <TEX>$s^{-l}$</TEX>), which are clearly distinct in space and velocity. The HVC may be a highly collimated jet presumed from its narrow velocity width and high velocity. The LVC, on the other hand, may be a widely opened disk wind inferred from its broad velocity width and low velocity. The spectrum taken perpendicular to the L1551 IRS 5 outflow at its base shows that the LVC has a spatially wide subcomponent, supporting the above interpretation. We demonstrated that the [Fe II] 1.644 <TEX>$\mu$</TEX> spectroscopy is a very powerful tool for the studies of fast jets and winds that directly emanate from star-disk systems.