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Beteiligte Max-Planck-Institute |
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MPI für Radioastronomie |
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Autoren |
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Khanzadyan, T.; Smith, M. D.; Gredel, R.; Stanke, T.; Davis, C. J. |
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Publikationstyp |
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Artikel |
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Titel |
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Active star formation in the large Bok globule CB34 |
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Zusammenfassung |
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We present near-infrared and millimetre observations of the large Bok globule CB34. Two long parallel trails of H-2 knots are discovered on wide-field images in the 1-0 S(1) 2.12 mum emission line. These parsec scale H-2 jets extend to the edge of the dark globule where they disappear without the trace of bow shocks. This suggests that the outflows physically extend into a lower density ambient medium where their terminating bows are beyond present detection limits. The two outflows are extremely well collimated and parallel to within 3degrees. The outflow mechanical luminosity, derived from CO measurements, and the shocked luminosity, estimated from the H-2 emission, are similar, consistent with jet-driven non-evolving outflow structure. The jets appear to originate from the densest cores, as observed in (HCO+)-C-13 line emission. A central concentration of reddened stars and a lower density halo of less reddened stars within the globule are revealed by JHK photometry. Disordered motions are observed in the CO J = 2-1 line velocity channel maps and can be driven by the power of the outflows emanating from dense cores. We sketch a picture for the star formation history of the globule in which two star phases have been formed. A weak diffuse emission halo is detected in the near infrared with colours consistent with either scattered light or a ro-vibrational H-2 cascade. We propose that the halo is produced by ongoing H-2 formation. Cloud evolution and halo H-2 formation timescales are then both a few x 10(5) yr. Thus, we may be witnessing the formation of a molecular cloud out of diffuse atomic gas. This supports a scheme in which this Bok globule has formed independently rather than through dislocation from a nearby molecular cloud. |
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Quelle |
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Astronomy & Astrophysics 383 (2), 502-518 (2002) |
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Sprache |
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English |
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Identifikation |
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ISI 000174184400011
ISSN 1432-0746 |
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Schlagworte |
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infrared : ISM; stars : formation; ISM : jets and out ows; ISM : clouds |
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© 2009, Max-Planck-Gesellschaft, München |
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