Adaptive‐Optics‐Assisted Near‐Infrared Spectroscopy of SVS 13 and Its Jet

We present long-slit H- and K-band spectroscopy of the low-mass outflowsource SVS 13, obtained with the adaptive-optics assisted imager-spectrometerNACO on the VLT. With a spatial resolution of < 0.25 arcsec and a pixel scaleof 0.027 arcsec we precisely establish the relative offsets of H2, [FeII], CO,HI and NaI components from the source continuum. The H2 and [FeII] peaks areclearly associated with the jet, while the CO, HI and NaI peaks are spatiallyunresolved and coincident with the source, as is expected for emissionassociated with accretion processes. The H2 profile along the slit is resolvedinto multiple components, which increase in size though decrease in intensitywith distance from the source. This trend might be consistent with thermalexpansion of packets of gas ejected during periods of increased accretionactivity. Indeed, for the brightest component nearest the source, proper motionmeasurements indicate a tangential velocity of 0.028 arcsec/year. It thereforeseems unlikely that this emission peak is associated with a stationary zone ofwarm gas at the base of the jet. However, the same can not be said for the[FeII] peak, for which we see no evidence for motion downwind, even thoughradial velocity measurements indicate that the emission is associated withhigher jet velocities. We postulate that the [FeII] could be associated with acollimation shock at the base of the jet.