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Energetic processes revealed by spectrally resolved high-J CO lines in low-mass star-forming regions with Herschel-HIFI

Published online by Cambridge University Press:  25 November 2011

U.A. Yıldız
Affiliation:
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands. e-mail: yildiz@strw.leidenuniv.nl ;
E.F. van Dishoeck
Affiliation:
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands. e-mail: yildiz@strw.leidenuniv.nl ; Max-Planck-Institut für Extraterrestrische Physik, 85748 Garching, Germany
L.E. Kristensen
Affiliation:
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands. e-mail: yildiz@strw.leidenuniv.nl ;
R. Visser
Affiliation:
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands. e-mail: yildiz@strw.leidenuniv.nl ;
G. Herczeg
Affiliation:
Max-Planck-Institut für Extraterrestrische Physik, 85748 Garching, Germany
T.A. van Kempen
Affiliation:
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands. e-mail: yildiz@strw.leidenuniv.nl ;
J.K. Jørgensen
Affiliation:
Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K., Denmark
M.R. Hogerheijde
Affiliation:
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands. e-mail: yildiz@strw.leidenuniv.nl ;
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Abstract

Herschel-HIFI observations of high-J lines (up to Ju = 10) of 12CO, 13CO and C18O are presented toward three deeply embedded low-mass protostars in NGC 1333. The observations show several energetic components including shocked and quiescent gas. Radiative transfer models are used to quantify the C18O envelope abundance which require a jump in the abundance at an evaporation temperature, Tev ~ 25 K, providing new direct evidence of a CO ice evaporation zone around protostars. The abundance in the outermost part of the envelope, X0, is within the canonical value of 2 × 10-4; however the inner abundance, Xin, is found around a factor of 3–5 lower than X0.

Type
Research Article
Copyright
© EAS, EDP Sciences 2011

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References

Jørgensen, J.K., Schöier, F.L., & van Dishoeck, E.F., 2005, A&A, 435, 177
Kristensen, L.E., et al., 2010, A&A, 521, L30
van Dishoeck, E.F., et al., 2011, PASP, accepted [astro-ph: 1012.4570]
Yıldız, U.A., et al., 2010, A&A, 521, L40