EDP Sciences
Free access
Volume 382, Number 3, February II 2002
Page(s) 1021 - 1031
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011680

A&A 382, 1021-1031 (2002)
DOI: 10.1051/0004-6361:20011680

Near-infrared Fabry-Perot imaging of Herbig-Haro energy sources: Collimated, small-scale H $\mathsf{_{2}}$ jets and wide-angled winds

C. J. Davis1, L. Stern1, 2, T. P. Ray3 and A. Chrysostomou4

1  Joint Astronomy Centre, 660 North A'ohoku Place, University Park, Hilo, Hawaii 96720, USA
2  Dept. of Physics, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
3  Dublin Institute for Advanced Studies, School of Cosmic Physics, 5 Merrion Square, Dublin 2, Ireland
4  Department of Physical Sciences, University of Hertfordshire, Hatfield, Herts AL10 9AB, UK

(Received 17 September 2001 / Accepted 23 November 2001)

To search for further evidence of H 2 line emission towards the central engines of Herbig-Haro (HH) flows we have obtained near-infrared Fabry-Perot images of eight Class I outflow sources (SVS 13 [HH 7-11], L 1551-IRS5, HH 26-IRS, HH 72-IRS, SSV 63E [HH 24C], SSV 63W [HH 24J], HH 34-IRS and HH 111-IRS) and two Class 0 sources (HH 24-MMS and HH 25-MMS). Elongated H 2 emission (on scales of a few arcseconds) is detected from four of the Class I YSOs. These small-scale "jets" are associated with the base of more extended, parsec-scale HH outflows (and the "Molecular Hydrogen Emission Line" regions, or MHELs, discussed in Davis et al. 2001). In L 1551-IRS 5 we detect two jet components in H 2; these may be the molecular counterparts of the two known optical jets from this binary protostellar system, or they may represent H 2 excitation along the walls of a narrow, edge-brightened cavity. In addition to the small-scale MHEL jets, analysis of the data also suggests the presence of discrete molecular shock fronts formed along the jet axes close to the energy sources. In the most clear-cut example, SVS 13, we see an H 2 knot at a distance of about 440 AU from the outflow source; assuming a flow velocity of ~200 km s -1, then the dynamical age of this molecular feature is only 10 yrs. In these data we also see evidence for both collimated jets and wide-angled winds from the same sources. Indeed, even in one of the two Class 0 sources, HH 25MMS, a poorly-collimated flow component seems to be present. A two-component wind model may therefore be appropriate for outflows from Class I (and possibly even Class 0) protostars.

Key words: interstellar medium: jets and outflows -- stars: pre-main-sequence -- Herbig-Haro objects

Offprint request: C. J. Davis, c.davis@jach.hawaii.edu

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