HIGH-VELOCITY BIPOLAR OUTFLOW AND DISKLIKE ENVELOPE IN THE CARBON STAR V HYDRAE

摘要

Using the partially completed Submillimeter Array with five antennas, we have observed the CO J = 2-1 and 3-2 emission from the envelope surrounding the carbon star V Hya. The high angular resolution (2″-4″) maps show that V Hya is powering a bipolar molecular jet with an extreme velocity of 70-185 km s~(-1). The axis of this high-velocity jet is perpendicular to the major axis of the flattened disklike envelope, which is expanding with a velocity of ～ 16 km s~(-1). There is a third kinematic component, a medium-velocity wind with a deprojected velocity of 40-120 km s~(-1) moving along the disk plane. Both the high-velocity jet and the medium-velocity wind have a dynamical timescale of a few hundred years. The flattened structure and the collimated jet observed in V Hya suggest that the formation of asymmetrical structure proceeds while the central star is still in the asymptotic giant branch phase.