The c2d Spitzer Spectroscopic Survey of Ices Around Low-Mass Young Stellar Objects. IV. NH3 and CH3OH

Abstract

NH3 and CH3OH are key molecules in astrochemical networks leading to the formation of more complex N- and O-bearing molecules, such as CH3CN and HCOOCH3. Despite a number of recent studies, little is known about their abundances in the solid state. (...) In this work, we investigate the ~ 8-10 micron region in the Spitzer IRS (InfraRed Spectrograph) spectra of 41 low-mass young stellar objects (YSOs). These data are part of a survey of interstellar ices in a sample of low-mass YSOs studied in earlier papers in this series. We used both an empirical and a local continuum method to correct for the contribution from the 10 micron silicate absorption in the recorded spectra. In addition, we conducted a systematic laboratory study of NH3- and CH3OH-containing ices to help interpret the astronomical spectra. We clearly detect a feature at ~9 micron in 24 low-mass YSOs. Within the uncertainty in continuum determination, we identify this feature with the NH3 nu_2 umbrella mode, and derive abundances with respect to water between ~2 and 15%. Simultaneously, we also revisited the case of CH3OH ice by studying the nu_4 C-O stretch mode of this molecule at ~9.7 micron in 16 objects, yielding abundances consistent with those derived by Boogert et al. 2008 (hereafter paper I) based on a simultaneous 9.75 and 3.53 micron data analysis. Our study indicates that NH3 is present primarily in H2O-rich ices, but that in some cases, such ices are insufficient to explain the observed narrow FWHM. The laboratory data point to CH3OH being in an almost pure methanol ice, or mixed mainly with CO or CO2, consistent with its formation through hydrogenation on grains. Finally, we use our derived NH3 abundances in combination with previously published abundances of other solid N-bearing species to find that up to 10-20 % of nitrogen is locked up in known ices.

31 pages, 15 figures, accepted for publication in ApJ

References in corpus (22)

• The Infrared Spectrograph on the Spitzer Space Telescope
• From Molecular Cores to Planet-forming Disks: A SIRTF Legacy Program
• The absence of crystalline silicates in the diffuse interstellar medium
• The c2d Spitzer Spectroscopic Survey of Ices Around Low-Mass Young Stellar Objects: I. H2O and the 5-8 um Bands
• The c2d Spitzer spectroscopic survey of ices around low-mass young stellar objects II: CO2
• C2D Spitzer-IRS spectra of disks around T Tauri stars: I. Silicate emission and grain growth
• The shape and composition of interstellar silicate grains
• Evolution of Chemistry and Molecular Line Profile during Protostellar Collapse
• The c2d Spitzer spectroscopy survey of ices around low-mass young stellar objects, III: CH4
• Mapping ices in protostellar environments on 1000 AU scales: Methanol-rich ice in the envelope of Serpens SMM 4
• Microscopic simulation of methanol and formaldehyde ice formation in cold dense cores
• A quantitative analysis of OCN- formation in interstellar ice analogs
• Spatial mapping of ices in the Oph-F core: A direct measurement of CO depletion and the formation of CO2
• A 3-5$\mu$m VLT spectroscopic survey of embedded young low mass stars II; OCN${}^{-}$
• Origin of the 6.85 micron band near young stellar objects: The ammonium ion (NH4+) revisited
• Spitzer Space Telescope Spectroscopy of Ices toward Low Mass Embedded Protostars
• Detection of abundant solid methanol toward young low mass stars
• Effects of CO2 on H2O band profiles and band strengths in mixed H2O:CO2 ices
• Collapsing Hot Molecular Cores: A Model for the Dust Spectrum and Ammonia Line Emission of the G31.41+0.31 Hot Core
• Infrared spectroscopy of HCOOH in interstellar ice analogues
• Band profiles and band strengths in mixed H2O:CO ices
• Cold gas as an ice diagnostic toward low mass protostars

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