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dc.creatorOberg, Karin I.en_US
dc.creatorBoogert, Adwin C. A.en_US
dc.creatorPontoppidan, Klaus M.en_US
dc.creatorBlake, Geoffrey A.en_US
dc.creatorEvans, Neal J.en_US
dc.creatorLahuis, Freden_US
dc.creatorvan Dishoeck, Ewine F.en_US
dc.date.accessioned2016-04-28T19:43:10Z
dc.date.available2016-04-28T19:43:10Z
dc.date.issued2008-05en
dc.identifierdoi:10.15781/T24N8W
dc.identifier.citation�berg, Karin I., AC Adwin Boogert, Klaus M. Pontoppidan, Geoffrey A. Blake, Neal J. Evans, Fred Lahuis, and Ewine F. Van Dishoeck. "The c2d spitzer spectroscopic survey of ices around low-mass young stellar objects. III. CH4." The Astrophysical Journal, Vol. 678, No. 2 (May., 2008): 1032.en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/35166
dc.description.abstractCH4 is proposed to be the starting point of a rich organic chemistry. Solid CH4 abundances have previously been determined mostly toward high-mass star-forming regions. Spitzer IRS now provides a unique opportunity to probe solid CH4 toward low-mass star-forming regions as well. Infrared spectra from the Spitzer Space Telescope are presented to determine the solid CH4 abundance toward a large sample of low-mass young stellar objects. A total of 25 out of 52 ice sources in the "Cores to Disks'' (c2d) Legacy program have an absorption feature at 7.7 mu m, attributed to the bending mode of solid CH4. The solid CH4/H2O abundances are 2%-8%, except for three sources with abundances as high as 11%-13%. The latter sources have relatively large uncertainties due to small total ice column densities. Toward sources with H2O column densities above 2 x 10(18) cm(-2), the CH4 abundances (20 out of 25) are nearly constant at 4.7% +/- 1.6%. Correlation plots with solid H2O, CH3OH, CO2, and CO column densities and abundances relative to H2O reveal a closer relationship of solid CH4 with CO2 and H2O than with solid CO and CH3OH. The inferred solid CH4 abundances are consistent with models where CH4 is formed through sequential hydrogenation of C on grain surfaces. Finally, the equal or higher abundances toward low-mass young stellar objects compared with high-mass objects and the correlation studies support this formation pathway as well, but not the two competing theories: formation from CH3OH and formation in gas phase with subsequent freezeout.en_US
dc.description.sponsorshipEuropean Early Stage Training Network MEST-CT-2004-504604en_US
dc.description.sponsorshipNWO Spinozaen_US
dc.description.sponsorshipHubble Fellowship 1201.01en_US
dc.description.sponsorshipNASA NAS 5-26555en_US
dc.language.isoEnglishen_US
dc.relation.ispartofen_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.subjectastrochemistryen_US
dc.subjectinfrared : ismen_US
dc.subjectism : abundancesen_US
dc.subjectism : moleculesen_US
dc.subjectstarsen_US
dc.subject: formationen_US
dc.subjectdense interstellar cloudsen_US
dc.subjectdeeply embedded protostarsen_US
dc.subjectmolecularen_US
dc.subjectcompositionen_US
dc.subjectinfrared observationsen_US
dc.subjectorganic-moleculesen_US
dc.subjectspace-telescopeen_US
dc.subjectmethaneen_US
dc.subjectgasen_US
dc.subjectchemistryen_US
dc.subjectstarsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleThe c2d Spitzer Spectroscopic Survey Of Ices Around Low-Mass Young Stellar Objects. III. CH4en_US
dc.typeArticleen_US
dc.description.departmentAstronomyen_US
dc.identifier.Filename2008_05_stellarobjectsiii.pdfen_US
dc.rights.restrictionOpenen_US
dc.identifier.doi10.1086/533432en_US
dc.contributor.utaustinauthorEvans, Neal J.en_US
dc.relation.ispartofserialAstrophysical Journalen_US


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