interstellar ices are an important dust component inside dense molecular clouds. the abundance of carbon-bearing molecules in ice mantles is not well known because the important molecules co2 and ch4 cannot be observed from the ground. observations of solid co (see fig.1 in appendix a) reveal that interstellar ices consist of different components: h2o-rich ices as well as ices dominated by non-polar molecules such as co, co2, or ch4. these distinct components, often associated with the same star, may result from outgassing of the highly volatile, non-polar molecules near protostars or from the predominance of different chemical routes at different times during the collapse or in different spatial zones around the protostar. understanding the influence of protostars on the composition of their natal molecular clouds is a key problem within astrophysics. a better understanding of the abundances of organic molecules in interstellar ices around low mass protostars will also lead to a better understanding of the organic inventory of comets and the outer ice planets and satellites in our solar system. using the sws, we propose to study the solid co2 and ch4 bands, which can not be done from the ground due to telluric co2 and ch4 absorption. in combination with ground based co and ch3oh data, we can then determine the abundances of the dominant carbon-bearing molecules in interstellar ices. the peak position and profile of the solid co2 and ch4 bands are sensitive to the solid state environment of these molecules and detailed comparison with laboratory profiles yields therefore additional, independent constraints on the non-polar ice composition (see figs.2 and 3 in appendix a). finally, because of their different chemical formation routes and volatility, solid co2 and ch4 studies allow direct tests of existing models for the origin of non-polar versus h2o-rich ices.
Instrument
SWS06
Temporal Coverage
1996-03-19T07:20:42Z/1997-10-31T07:15:06Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
