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Molecular oxygen in the rho Ophiuchi cloud

Research output: Contribution to journalArticlepeer-review

Published copy (DOI)


  • B. Larsson
  • R. Liseau
  • L. Pagani
  • P. Bergman
  • N. Biver
  • J. H. Black
  • R. S. Booth
  • V. Buat
  • J. Crovisier
  • C. L. Curry
  • M. Dahlgren
  • P. J. Encrenaz
  • E. Falgarone
  • P. A. Feldman
  • M. Fich
  • H. G. Floren
  • M. Fredrixon
  • U. Frisk
  • G. F. Gahm
  • M. Gerin
  • M. Hagstrom
  • J. Harju
  • T. Hasegawa
  • A. Hjalmarson
  • L. E. B. Johansson
  • K. Justtanont
  • A. Klotz
  • E. Kyrola
  • S. Kwok
  • A. Lecacheux
  • T. Liljestrom
  • E. J. Llewellyn
  • S. Lundin
  • G. Megie
  • G. F. Mitchell
  • D. Murtagh
  • L. H. Nordh
  • L.-A. Nyman
  • M. Olberg
  • A. O. H. Olofsson
  • G. Olofsson
  • H. Olofsson
  • G. Persson
  • R. Plume
  • H. Rickman
  • I. Ristorcelli
  • G. Rydbeck
  • A. A. Sandqvist
  • F. V. Scheele
  • G. Serra
  • S. Torchinsky
  • N. F. Tothill
  • K. Volk
  • T. Wiklind
  • C. D. Wilson
  • A. Winnberg
  • G. Witt


Publication details

JournalAstronomy & Astrophysics
DatePublished - May 2007
Issue number3
Number of pages11
Pages (from-to)999-U158
Original languageEnglish


Context. Molecular oxygen, O-2, has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O-2 emission.

Aims. The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium.

Methods. The Odin satellite carries a 1.1m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O-2. Starting in 2002, the star forming molecular cloud core rho OphA was observed with Odin for 34 days during several observing runs.

Results. We detect a spectral line at v(LSR)= + 3.5 km s(-1) with = vFWHM = 1.5 km s(-1), parameters which are also common to other species associated with rho OphA. This feature is identified as the O-2 (N-J = 1(1)- 1(0)) transition at 118 750.343 MHz.

Conclusions. The abundance of molecular oxygen, relative to H-2, is 5 x 10(-8) averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits.

    Research areas

  • ISM : individual objects : rho OphA, ISM : clouds, ISM : molecules, ISM : abundances, stars : formation, radio lines : ISM, ODIN SATELLITE, DARK CLOUD, ABUNDANCE, O-2, HIGHLIGHTS, CHEMISTRY, EMISSION, C-C2H4O, REGIONS, CORES

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