Shockingly Low Water Abundances In Herschel/PACS Observations Of Low-Mass Protostars In Perseus

Simple item page
dc.contributor.utaustinauthorEvans, Neal J.en_US
dc.creatorKarska, A.en_US
dc.creatorKristensen, L. E.en_US
dc.creatorvan Dishoeck, E. F.en_US
dc.creatorDrozdovskaya, M. N.en_US
dc.creatorMottram, J. C.en_US
dc.creatorHerczeg, G. J.en_US
dc.creatorBruderer, S.en_US
dc.creatorCabrit, S.en_US
dc.creatorEvans, Neal J.en_US
dc.creatorFedele, D.en_US
dc.creatorGusdorf, A.en_US
dc.creatorJorgensen, J. K.en_US
dc.creatorKaufman, M. J.en_US
dc.creatorMelnick, G. J.en_US
dc.creatorNeufeld, D. A.en_US
dc.creatorNisini, B.en_US
dc.creatorSantangelo, G.en_US
dc.creatorTafalla, M.en_US
dc.creatorWampfler, S. F.en_US
dc.date.accessioned2016-04-22T19:45:51Z
dc.date.available2016-04-22T19:45:51Z
dc.date.issued2014-12en
dc.description.abstractContext. Protostars interact with their surroundings through jets and winds impinging on the envelope and creating shocks, but the nature of these shocks is still poorly understood. Aims. Our aim is to survey far-infrared molecular line emission from a uniform and significant sample of deeply-embedded low-mass young stellar objects (YSOs) in order to characterize shocks and the possible role of ultraviolet radiation in the immediate protostellar environment. Methods. Herschel/PACS spectral maps of 22 objects in the Perseus molecular cloud were obtained as part of the William Herschel Line Legacy WILL) survey. Line emission from H2O, CO, and OH is tested against shock models from the literature. Results. Observed line ratios are remarkably similar and do not show variations with physical parameters of the sources (luminosity, envelope mass). Most ratios are also comparable to those found at off-source outflow positions. Observations show good agreement with the shock models when line ratios of the same species are compared. Ratios of various H2O lines provide a particularly good diagnostic of pre-shock gas densities, n(H) similar to 10(5) cm(-3), in agreement with typical densities obtained from observations of the post-shock gas when a compression factor on the order of 10 is applied (for non-dissociative shocks). The corresponding shock velocities, obtained from comparison with CO line ratios, are above 20 km s(-1). However, the observations consistently show H2O-to-CO and H2O-to-OH line ratios that are one to two orders of magnitude lower than predicted by the existing shock models. Conclusions. The overestimated model H2O fluxes are most likely caused by an overabundance of H2O in the models since the excitation is well-reproduced. Illumination of the shocked material by ultraviolet photons produced either in the star-disk system or, more locally, in the shock, would decrease the H2O abundances and reconcile the models with observations. Detections of hot H2O and strong OH lines support this scenario.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipPolish National Science Center 2013/111N/ST9/00400en_US
dc.description.sponsorshipNetherlands Research School for Astronomy (NOVA)en_US
dc.description.sponsorshipRoyal Netherlands Academy of Arts and Sciences (KNAW)en_US
dc.description.sponsorshipSpinoza granten_US
dc.description.sponsorshipNetherlands Organisation for Scientific Research (NWO) 614.001.008en_US
dc.description.sponsorshipEuropean Conununity 238258en_US
dc.description.sponsorshipNASA through Jet Propulsion Laboratory, California Institute of Technologyen_US
dc.identifierdoi:10.15781/T2DV3J
dc.identifier.citationKarska, A., L. E. Kristensen, E. F. Van Dishoeck, M. N. Drozdovskaya, J. C. Mottram, G. J. Herczeg, S. Bruderer et al. >Shockingly low water abundances in Herschel/PACS observations of low-mass protostars in Perseus.> Astronomy & Astrophysics, Vol. 572 (Dec., 2014): A9.en_US
dc.identifier.doi10.1051/0004-6361/201424166en_US
dc.identifier.issn0004-6361en_US
dc.identifier.urihttp://hdl.handle.net/2152/34413
dc.language.isoEnglishen_US
dc.relation.ispartofserialAstronomy & Astrophysicsen_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.subjectstars: formationen_US
dc.subjectism: jets and outflowsen_US
dc.subjectyoung stellar objectsen_US
dc.subjectstar-forming regionsen_US
dc.subjecthigh-j coen_US
dc.subjectspectralen_US
dc.subjectenergy-distributionsen_US
dc.subjectmagnetic molecular shocksen_US
dc.subjecttime digit herschelen_US
dc.subjectspitzer c2d surveyen_US
dc.subjectngc 1333en_US
dc.subjectline emissionen_US
dc.subjecth-2 emissionen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleShockingly Low Water Abundances In Herschel/PACS Observations Of Low-Mass Protostars In Perseusen_US
dc.typeArticleen_US

Access full-text files

Original bundle

Now showing 1 - 1 of 1
Thumbnail Image
Name:
lowwaterabundancesherschel.pdf
Size:
2.71 MB
Format:
Adobe Portable Document Format
Download

Collections

UT Faculty/Researcher Works