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First hyperfine structure resolved OH FIR spectrum of a star-forming region

dc.contributor.authorS. F., Wampfler
dc.contributor.authorBRUDERER, S.
dc.contributor.authorL. E., Kristensen
dc.contributor.authorE. A., Bergin
dc.contributor.authorA. O., Benz
dc.contributor.authorDISHOECK E. F., Van
dc.contributor.authorG. J., Herczeg
dc.contributor.authorDER TAK F. F. S., Van
dc.contributor.authorJ. R., Goicoechea
dc.contributor.authorS. D., Doty
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierUniversité Sciences et Technologies - Bordeaux 1 [UB]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
dc.contributor.authorHERPIN, Fabrice
dc.date.created2011
dc.date.issued2011
dc.date.conference2011
dc.description.abstractEnEmbedded protostars interact with their natal cloud through shocks and irradiation. The ambient interstellar medium warms up, allowing icy grain mantles to evaporate and making different chemical routes in the gas phase available. Water then becomes one of the most abundant molecular species in the gas phase. The Herschel key program 'Water in Star-Forming Regions with Herschel (WISH)' studies the excitation and chemistry of water around protostars. Hydroxyl (OH) is of the cornerstone species in the water chemistry network, because it is closely linked to both the formation and destruction of water through the OH + H2 leftrightarrow H2O + H reactions and photodissociation processes. This poster presents the first OH observation with resolved hyperfine structure at 163 μm of a star-forming region obtained using HIFI on Herschel. The OH triplet from the high-mass star-forming region W3 IRS5 is in emission, with the line profile revealing a narrow component on top of a broad feature. The broad component is attributed to outflow emission based on comparison with molecular lines of other species, whereas the narrow component is in agreement with radiative transfer results for a spherically symmetric envelope model. The resolved hyperfine structure allows us to constrain the excitation temperature and the OH column density in our models simultaneously. The derived OH/H2O ratios in the envelope are consistent with the current picture of the water chemistry. In the outer envelope (T < 100 K), where OH and H2O are released into the gas phase by photodesorption from the ice mantles of dust grains, we find a ratio of about unity. Laboratory work by Öberg et al. (2009) demonstrated that similar amounts of OH and water are released with an expected OH/H2O ratio of 0.5-1. This ratio is also in agreement with the theoretical work by Andersson & van Dishoeck (2008). In the inner envelope (T > 100 K), water is efficiently formed from OH and the OH/H2O ratio is therefore expected to drop significantly, which is consistent with the derived value of the order of 10-4. For the outflow, a lower limit of OH/H2O > 0.025 is obtained and can be explained with either a fast J-type shock or a slower UV irradiated C-type shock.
dc.language.isoen
dc.source.titleThe Molecular Universe, Posters from the proceedings of the 280th Symposium of the International Astronomical Union held in Toledo, Spain, May 30-June 3, 2011, #380 - 2011IAUS..280P.380W
dc.title.enFirst hyperfine structure resolved OH FIR spectrum of a star-forming region
dc.typeCommunication dans un congrès
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Astrophysique stellaire et solaire [astro-ph.SR]
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Astrophysique stellaire et solaire [astro-ph.SR]
bordeaux.page-
bordeaux.volume-
bordeaux.conference.titleThe Molecular Universe
bordeaux.countryES
bordeaux.title.proceedingThe Molecular Universe, Posters from the proceedings of the 280th Symposium of the International Astronomical Union held in Toledo, Spain, May 30-June 3, 2011, #380 - 2011IAUS..280P.380W
bordeaux.conference.cityTolede
bordeaux.peerReviewedoui
hal.identifierhal-00606006
hal.version1
hal.invitednon
hal.proceedingsoui
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00606006v1
bordeaux.COinSctx_ver=Z39.88-2004&amp;rft_val_fmt=info:ofi/fmt:kev:mtx:journal&amp;rft.btitle=The%20Molecular%20Universe,%20Posters%20from%20the%20proceedings%20of%20the%20280th%20Symposium%20of%20the%20International%20Astronomical%20Union%20held%20in%20Toledo,%2&amp;rft.date=2011&amp;rft.volume=-&amp;rft.spage=-&amp;rft.epage=-&amp;rft.au=S.%20F.,%20Wampfler&amp;BRUDERER,%20S.&amp;L.%20E.,%20Kristensen&amp;E.%20A.,%20Bergin&amp;A.%20O.,%20Benz&amp;rft.genre=unknown


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