The following document lists the file abstract/PWESSELI_13CO2ICE.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
======================================================================== ==> In this proposal, more time is being requested for PWESSELI.CO2CH4IF ======================================================================== Interstellar ices are an important dust component inside dense molecular clouds. ISO-SWS observations have revealed that CO2 is the most abundant carbon-bearing molecule in ice mantles. The line profiles indicate the presence of distinct ice mantle components: H2O-rich ices as well as ices dominated by non-polar molecules such as CO and CO2. These components 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 extend our successful observations of interstellar solid CO2. We propose to measure the 13CO2 stretching and 12CO2 bending modes for sources with an optically thick 12CO2 stretching mode. The composition of the ice mantles in which the CO2 is trapped will be determined from the column densities and the line profiles. Laboratory studies show that 13CO2 behaves in many ways as an independent probe of the molecular environment, because it is always a trace species in the ice. An important second goal of these observations will be to determine the galactic 12C/13C abundance ratio. This will put important constraints on models of galactic chemical evolution. ISO will be the only platform from which one can observe the interstellar 12CO2 and 13CO2 molecules for the next decade(s), and thereby determine the composition of ice mantles and the solid state 12C/13C ratio.