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

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dc.contributor.utaustinauthorEvans, Neal J.en_US
dc.creatorBottinelli, Sandrineen_US
dc.creatorBoogert, Adwin C. A.en_US
dc.creatorBouwman, Jordyen_US
dc.creatorBeckwith, Marthaen_US
dc.creatorvan Dishoeck, Ewine F.en_US
dc.creatorOberg, Karin I.en_US
dc.creatorPontoppidan, Klaus M.en_US
dc.creatorLinnartz, H.en_US
dc.creatorBlake, Geoffrey A.en_US
dc.creatorEvans, Neal J.en_US
dc.creatorLahuis, Freden_US
dc.date.accessioned2016-04-28T19:43:07Z
dc.date.available2016-04-28T19:43:07Z
dc.date.issued2010-08en
dc.description.abstractNH3 and CH3OH are key molecules in astrochemical networks leading to the formation of more complex N- and O-bearing molecules, such as CH3CN and CH3OCH3. Despite a number of recent studies, little is known about their abundances in the solid state. This is particularly the case for low-mass protostars, for which only the launch of the Spitzer Space Telescope has permitted high-sensitivity observations of the ices around these objects. In this work, we investigate the similar to 8-10 mu m 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 mu m 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 similar to 9 mu m 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 similar to 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 similar to 9.7 mu m in 16 objects, yielding abundances consistent with those derived by Boogert et al. based on a simultaneous 9.75 and 3.53 mu m 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.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipSpitzer Legacy Science Programen_US
dc.description.sponsorshipNASA 1224608, 1230779, 1230782, 1256316, 1279952en_US
dc.description.sponsorshipNetherlands Organization for Scientific Research (NWO)en_US
dc.description.sponsorshipStichting voor Fundamenteel Onderzoek der Materie (FOM)en_US
dc.description.sponsorshipThe Netherlands Research School for Astronomy (NOVA)en_US
dc.description.sponsorshipEuropean Early Stage Training Network MEST-CT-2004-504604en_US
dc.description.sponsorshipNASA through Hubble Fellowship by Space Telescope Science Institute 1201.01en_US
dc.identifierdoi:10.15781/T28C0B
dc.identifier.Filename2010_08_stellarobjectsiv.pdfen_US
dc.identifier.citationBottinelli, Sandrine, AC Adwin Boogert, Jordy Bouwman, Martha Beckwith, Ewine F. Van Dishoeck, Karin I. �berg, Klaus M. Pontoppidan et al. "The c2d Spitzer spectroscopic survey of ices around low-mass young stellar objects. IV. NH3 and CH3OH." The Astrophysical Journal, Vol. 718, No. 2 (Aug., 2010): 1100.en_US
dc.identifier.doi10.1088/0004-637x/718/2/1100en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/35165
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialAstrophysical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.rights.restrictionOpenen_US
dc.subjectastrochemistryen_US
dc.subjectinfrared: ismen_US
dc.subjectism: abundancesen_US
dc.subjectism: moleculesen_US
dc.subjectstars:en_US
dc.subjectformationen_US
dc.subjectinfrared band strengthsen_US
dc.subjectinterstellar iceen_US
dc.subjectspace-telescopeen_US
dc.subjectlaboratoryen_US
dc.subjectsimulationsen_US
dc.subjectmolecular cloudsen_US
dc.subjectsolid methanolen_US
dc.subjectstar-formationen_US
dc.subjectw 33aen_US
dc.subjectprotostarsen_US
dc.subjectanalogsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleThe c2d Spitzer Spectroscopic Survey Of Ices Around Low-Mass Young Stellar Objects. IV. NH3 And CH3OHen_US
dc.typeArticleen_US

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