Herschel/HIFI observations of high-J CO lines in the NGC 1333 low-mass star-forming region

U. A. Yildiz*, E. F. van Dishoeck, L. E. Kristensen, R. Visser, J. K. Jorgensen, G. J. Herczeg, T. A. van Kempen, M. R. Hogerheijde, S. D. Doty, A. O. Benz, S. Bruderer, S. F. Wampfler, E. Deul, R. Bachiller, A. Baudry, M. Benedettini, E. Bergin, P. Bjerkeli, G.A. Blake, S. BontempsJ. Braine, P. Caselli, J. Cernicharo, C. Codella, F. Daniel, A. M. di Giorgio, C. Dominik, P. Encrenaz, M. Fich, A. Fuente, T. Giannini, J. R. Goicoechea, Th. de Graauw, F. Helmich, F. Herpin, T. Jacq, D. Johnstone, B. Larsson, D. Lis, R. Liseau, F.-C. Liu, M. Marseille, C. McCoey, G. Melnick, D. Neufeld, B. Nisini, M. Olberg, B. Parise, J. C. Pearson, R. Plume, C. Risacher, J. Santiago-Garcia, P. Saraceno, R. Shipman, M. Tafalla, A. G. G. M. Tielens, F. van der Tak, F. Wyrowski, P. Dieleman, W. Jellema, V. Ossenkopf, R. Schieder, J. Stutzki

*Corresponding author for this work

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Abstract

Herschel/HIFI observations of high-J lines (up to J(u) = 10) of (CO)-C-12, (CO)-C-13 and (CO)-O-18 are presented toward three deeply embedded low-mass protostars, NGC 1333 IRAS 2A, IRAS 4A, and IRAS 4B, obtained as part of the Water In Star-forming regions with Herschel (WISH) key program. The spectrally-resolved HIFI data are complemented by ground-based observations of lower-J CO and isotopologue lines. The (CO)-C-12 10-9 profiles are dominated by broad (FWHM 25-30 km s(-1)) emission. Radiative transfer models are used to constrain the temperature of this shocked gas to 100-200 K. Several CO and (CO)-C-13 line profiles also reveal a medium-broad component (FWHM5-10 km s(-1)), seen prominently in H2O lines. Column densities for both components are presented, providing a reference for determining abundances of other molecules in the same gas. The narrow (CO)-O-18 9-8 lines probe the warmer part of the quiescent envelope. Their intensities require a jump in the CO abundance at an evaporation temperature around 25 K, thus providing new direct evidence for a CO ice evaporation zone around low-mass protostars.

Original languageEnglish
Article numberL40
Number of pages7
JournalAstronomy & astrophysics
Volume521
DOIs
Publication statusPublished - Oct-2010

Keywords

  • astrochemistry
  • stars: formation
  • ISM: jets and outflows
  • ISM: molecules
  • NGC-1333 IRAS-4
  • DENSE CORES
  • PROTOSTARS
  • ENVELOPES
  • ABUNDANCE
  • H2CO
  • EVOLUTION
  • WATER
  • DUST
  • HIFI

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