Forum Springer Astron. Astrophys.
Forum Whats New Search Orders

Astron. Astrophys. 346, L57-L60 (1999)

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5. Conclusions

In summary, a search for solid O2 toward the most promising cold clouds with ISO-SWS and ground-based observations has led to an upper limit on the amount of condensable oxygen found in the form of O2 ice of 10%. Recent observations with the sub-mm satellite SWAS (Submillimeter Wave Astronomy Satellite) have confirmed the low abundance of gaseous O2 in cold clouds, such as NGC 7538 IRS9. Furthermore, the amount of oxygen found in "cold" H2O toward such targets is negligible. The low abundances of solid and gaseous O2 suggest that O0 should be the dominant form of oxygen in dense clouds. Further measurements with SWAS using longer integration times and future space missions will give more conclusive evidence on the abundance of gas phase O2 in interstellar clouds.

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© European Southern Observatory (ESO) 1999

Online publication: June 17, 1999