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Molecular oxygen in the rho Ophiuchi cloud
Stockholm University, Faculty of Science, Department of Astronomy.
Stockholm University, Faculty of Science, Department of Astronomy.
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2007 (English)In: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 466, no 3, 5- p.Article in journal (Refereed) Published
Abstract [en]

Context: Molecular oxygen, O2, 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 O2 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 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O2. Starting in 2002, the star forming molecular cloud core ρ Oph A 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 Δ v_FWHM=1.5 km s-1, parameters which are also common to other species associated with ρ Oph A. This feature is identified as the O2 (NJ = 11 - 1_0) transition at 118 750.343 MHz.

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

Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Étude Spatiale (CNES). The Swedish Space Corporation has been the industrial prime contractor and also is operating the satellite. Appendix A is only available in electronic form at

Place, publisher, year, edition, pages
2007. Vol. 466, no 3, 5- p.
Keyword [en]
molecules, abundances, star formation
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-19417DOI: doi:10.1051/0004-6361:20065500OAI: diva2:185941
Available from: 2007-11-09 Created: 2007-11-09 Last updated: 2011-01-11Bibliographically approved

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Larsson, BengtFlorén, Hans-GustavGahm, GöstaNordh, LennartOlofsson, GöranOlofsson, HansSandqvist, Aage
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