Observations of CO in L1551 - Evidence for stellar wind driven shocks

Abstract

CO observations reveal the presence of a remarkable, double-lobed structure in the molecular cloud L1551. The two lobes extend for about 0.5 pc in opposite directions from an infrared source buried within the cloud; one lobe is associated with the Herbig-Haro objects HH28, HH29, and HH102. It is suggested that the CO emission in the double-lobed structure arises from a dense shell of material which has been swept up by a strong stellar wind from the infrared source. This wind has a velocity of 200 km/s, and evidently is channeled into two oppositely directed streams. The CO observations indicate that the shell has a velocity of 15 km/s, a mass of 0.3 solar masses and a kinetic temperature of 8-35 K. Its age is roughly 30,000 years. A stellar mass-loss rate of 8 x 10 to the -7th solar masses per yr would be sufficient to create such a shell.