2002ApJ...580..959N

We present near-infrared images in H₂at 2.12 µm of the HH 7/11 outflow and its driving source SVS 13 taken with the Hubble Space Telescope NICMOS2 camera, as well as archival Hα and [S II] optical images obtained with the Wide Field Planetary Camera 2 (WFPC2). The Near-Infrared Camera and Multi-Object Spectrometer high angular resolution observations confirm the nature of a small-scale jet arising from SVS 13 and resolve a structure in the HH 7 working surface that could correspond to Mach disk H₂emission. The H₂jet has a length of 430 AU (at a distance of 350 pc) and an aspect ratio of 2.2 and morphologically resembles the well-known DG Tau optical microjet. The kinematical age of the jet (∼10 yr) coincides with the time since the last outburst from SVS 13. If we interpret the observed H₂flux density with molecular shock models of 20-30 km.s^–1, then the jet has a density as high as 10⁵ cm^–3. The presence of this small jet warns that contamination by H₂emission from an outflow in studies searching for H₂ in circumstellar disks is possible. At the working surface, the smooth H₂ morphology of the HH 7 bow shock indicates that the magnetic field is strong, playing a major role in stabilizing this structure. The H₂flux density of the Mach disk, when compared with that of the bow shock, suggests that its emission is produced by molecular shocks of less than 20 km.s^–1. The WFPC2 optical images display several of the global features already inferred from ground-based observations, like the filamentary structure in HH 8 and HH 10, which suggests a strong interaction of the outflow with its cavity. The H₂jet is not detected in [S II] or Hα; however, there is a small clump at ∼5 " northeast of SVS 13 that could be depicting the presence of either a different outburst event or the north edge of the outflow cavity.