Two Jets from the Protostellar System L1551 IRS 5

Abstract

Hubble Space Telescope and ground-based observations of the jet emanating from the young stellar object L1551 IRS 5 clearly show a structure with two components, one of which terminates in a working surface only 1500 AU from the originating sources. This particular jet is found to be less dense than the ambient medium. Its Mach disk is found to be very small, only ~45 AU. We show that this jet cannot be the driver of the large-scale molecular outflow in L1551 for two reasons: (1) the jet fails to provide the necessary momentum by at least a factor of 100, and, (2) having a dynamic age ~3 orders of magnitude less than that of the outflow, this jet has no causal relationship with the molecular flow. The morphology and velocity field of the two components are consistent with them being separate entities, and we suggest that there are in fact two jets, each possibly originating from a different young stellar object.

Based on observations made with the Nordic Optical Telescope, operated jointly on the island of La Palma by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, and based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.