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Summary: Astronomy & Astrophysics manuscript no. hh211 October 27, 2004
(DOI: will be inserted by hand later)
The nearinfrared excitation of the HH 211 protostellar outflow #
Barry O'Connell 1,2 , Michael D. Smith 1 , Dirk Froebrich 3 , Christopher J. Davis 4 , and Jochen Eislo#el 5
1 Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK
2 Physics Department, Trinity College Dublin, College Green, Dublin 2, Ireland
3 School of Cosmic Physics, Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
4 Joint Astronomy Centre, 660 N.A'ohoku Place, University Park, Hilo, Hawaii 96720, USA
5 Thuringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenberg, Germany
Received ...... / Accepted ........
Abstract. The protostellar outflow HH 211 is of considerable interest since it is extremely young and highly collimated. Here,
we explore the outflow through imaging and spectroscopy in the nearinfrared to determine if there are further diagnostic
signatures of youth. We confirm the detection of a nearinfrared continuum of unknown origin. We propose that it is emitted
by the driving millimeter source, escapes the core through tunnels, and illuminates features aligning the outflow. Narrowband
flux measurements of these features contain an unusually large amount of continuum emission. [FeII] emission at 1.644 µm
has been detected and is restricted to isolated condensations. However, the characteristics of vibrational excitation of molecular
hydrogen resemble those of older molecular outflows. We attempt to model the ordered structure of the western outflow as a
series of shocks, finding that bow shocks with Jtype dissociative apices and Ctype flanks are consistent. Moreover, essentially
the same conditions are predicted for all three bows except for a systematic reduction in speed and density with distance from
the driving source. We find increased Kband extinctions in the bright regions as high as 2.9 magnitudes and suggest that the
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