Spitzer Space Telescope - Theoretical Research Proposal #30331


Theoretical Studies of Ice Formation in the Dynamic Interstellar
Medium

Principal Investigator: Edwin Bergin
           Institution: University of Michigan

Co-Investigators: 
Eric Herbst, The Ohio State University                                

Science Category: ISM 
Dollars Approved: 90805.0 

Abstract:
A part of the Spitzer legacy to interstellar medium (ISM) science will
be a significant contribution to the characterization of molecular
ices.  Within our galaxy ice absorption features are detected by
Spitzer towards every embedded protostar, stars that lie behind
molecular clouds, and in absorption against the galactic infrared
background.  Numerous studies have focused on the carbon dioixide
(CO2) molecule as the detection of its vibrational models requires
space-borne platforms.  Analysis of Spitzer data is providing clues to
the origin of molecular ices and CO2 in particular.  This has
implications beyond chemistry in the ISM as interstellar and cometary
ices show striking similarities in composition.  However, there is
little effort being placed on a theoretical underpinning of how the
ice forms.  We propose to take theoretical studies of ice formation,
with an emphasis on CO2, in new directions by coupling recent
dynamical models of molecular cloud formation to state-of-the-art gas
and surface chemistry networks.  In this fashion, we will constrain
which ices form in abundance as low density gas condenses to form
molecular clouds, thereby setting the initial chemical conditions for
cloud fragmentation and star formation.