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Abstract: We present here an extensive analysis of the protostellar jet driven by IRAS20126+4104, deriving the kinematical, dynamical, and physical conditions of theH2 gas along the flow. The jet has been investigated by means of near-IR H2 andFeII narrow-band imaging, high resolution spectroscopy of the 1-0S1 line2.12 um, NIR 0.9-2.5 um low resolution spectroscopy, along with ISO-SWS andLWS spectra from 2.4 to 200 um. The flow shows a complex morphology. Inaddition to the large-scale jet precession presented in previous studies, wedetect a small-scale wiggling close to the source, that may indicate thepresence of a multiple system. The peak radial velocities of the H2 knots rangefrom -42 to -14 km s^-1 in the blue lobe, and from -8 to 47 km s^-1 in the redlobe. The low resolution spectra are rich in H 2 emission, and relatively faintFeII NIR, OI and CII FIR emission is observed in the region close tothe source. A warm H2 gas component has an average excitation temperature thatranges between 2000 K and 2500 K. Additionally, the ISO-SWS spectrum revealsthe presence of a cold component 520 K, that strongly contributes to theradiative cooling of the flow and plays a major role in the dynamics of theflow. The estimated LH2 of the jet is 8.2+-0.7 L sun, suggesting thatIRAS20126+4104 has an accretion rate significantly increased compared tolow-mass YSOs. This is also supported by the derived mass flux rate from the H2lines MfluxH2~7.5x10^-4 M sun yr^-1. The comparison between the H2 and theoutflow parameters strongly indicates that the jet is driving, at leastpartially, the outflow. As already found for low-mass protostellar jets, themeasured H2 outflow luminosity is tightly related to the source bolometricluminosity.

Autor: A. Caratti o Garatti 1, D. Froebrich 2, J. Eisloeffel 1, T. Giannini 3, B. Nisini 3 1 Thueringer Landessternwarte Tautenburg, 2 C



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