Contents of: VI/111/./abstract/PEHRENFR_SOLOXY.abs

The following document lists the file abstract/PEHRENFR_SOLOXY.abs from catalogue VI/111.
A plain copy of the file (without headers/trailers) may be downloaded.


The abundance of molecular oxygen in dense molecular clouds is a key problem
within astrochemistry. The interstellar medium is thought to be oxygen-rich
(elemental C/O=0.5) and all theoretical models predict that the oxygen not
locked up in CO will be in O2. However, despite sensitive searches, gaseous O2
has never been detected in the interstellar medium or in other galaxies. The
derived upper limits are in the order of O2/CO < 0.01. Hence it has been
suggested that the excess O is frozen out in icy grain mantles. Theoretical
models of icy grain mantles predict that O2 can be an important grain mantle
molecule in apolar ices in dense molecular clouds. Recent laboratory data show
that O2 can be detected directly through the weak fundamental transition at 6.4
mu or by observing the photolysis product O3 at 9.7 mu. Large spectroscopic
databases on CO and CO2 ices as well as isolated water ice - created for ISO -
revealed that O2 leaves its "fingerprints" in the profiles of the strong CO and
CO2 bands and shifts strongly the position of isolated water ice bands. This
combined spectroscopic information can be used as a powerful tool to make the
search for solid molecular oxygen with ISO successful.
We propose high resolution spectroscopic observations with the ISO satellite
towards a number of embedded sources and star-forming regions in order to
detect solid molecular oxygen and the sharp transition of its photolysis
product ozone. For our objects which have a typical visual extinction of 20
mag, we would be able to detect the solid O2 feature if the solid O2 abundance
is larger than   10 % of the elemental O. The detection of solid molecular
oxygen and ozone and the estimation of their abundances provide strong
constraints for the oxygen budget in the interstellar medium. New laboratory
data on solid O2 are the basis of this extended version related to the previous
proposal OXYOZONE/Open time, accepted in Cat.A.





© Université de Strasbourg/CNRS

    • Contact