title: Processing of icy mantles in protostellar envelopes.
abstract: We have obtained CO absorption profiles of several young stellar objects (YSOs), spanning a range of mass and luminosity, in order to investigate their ice mantle composition. We present the first detection of CO toward the class I YSO L1489 IRS in the Taurus dark cloud. In general, the CO profiles for YSOs show evidence for both processed and pristine ices in the same line of sight, strong indirect evidence for CO, is suggested in R CrA IRS 7, L1489 IRS, Elias 18, and GL 961E. Toward other sources (R CrA IRS 1, IRS 2, W33A, NGC 7538 IRS 9, Mon R2 IRS 2) CO is present in (nearly) pure form. We propose an evolutionary scenario to explain the chemical diversity of the icy mantles toward these objects.
authors.affiliation: Rensselaer Polytechnic Institute, Department of Physics, Applied Physics, and Astronomy, Troy, NY 12180, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Chiar
authors.forename: P A
authors.initials: PA
authors.lastname: Gerakines
authors.forename: D C
authors.initials: DC
authors.lastname: Whittet
authors.forename: Y J
authors.initials: YJ
authors.lastname: Pendleton
authors.forename: A G
authors.initials: AG
authors.lastname: Tielens
authors.forename: A J
authors.initials: AJ
authors.lastname: Adamson
authors.forename: A C
authors.initials: AC
authors.lastname: Boogert
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D002245:Carbon Dioxide / Q000032:analysis* / Q000737:chemistry; D002248:Carbon Monoxide / Q000032:analysis* / Q000737:chemistry; D019443:Cosmic Dust / Q000032:analysis*; D005118:Extraterrestrial Environment; D007053:Ice / Q000032:analysis*; D013057:Spectrum Analysis
chemical_list: D019443:Cosmic Dust; D007053:Ice; D002245:Carbon Dioxide; D002248:Carbon Monoxide