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The cooling of atomic and molecular gas in DR21

dc.contributor.authorJAKOB, H.
dc.contributor.authorKRAMER, C.
dc.contributor.authorSIMON, R.
dc.contributor.authorSCHNEIDER, N.
dc.contributor.authorOSSENKOPF, V.
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
dc.contributor.authorBONTEMPS, Sylvain
dc.contributor.authorGRAF, U. U.
dc.contributor.authorSTUTZKI, J.
dc.date.created2007
dc.date.issued2007
dc.identifier.issn0004-6361
dc.description.abstractEnWe present an overview of a high-mass star formation region through the major (sub-)mm, and far-infrared cooling lines to gain insight into the physical conditions and the energy budget of the molecular cloud. We used the KOSMA 3m telescope to map the core ($10'\times 14'$) of the Galactic star forming region DR 21/DR 21 (OH) in the Cygnus X region in the two fine structure lines of atomic carbon CI and four mid-$J$ transitions of CO and $^{13}$CO, and CS $J=7\TO6$. These observations have been combined with FCRAO $J=1\TO0$ observations of $^{13}$CO and C$^{18}$O. Five positions, including DR21, DR21 (OH), and DR21 FIR1, were observed with the ISO/LWS grating spectrometer in the \OI 63 and 145 $\mu$m lines, the \CII 158 $\mu$m line, and four high-$J$ CO lines. We discuss the intensities and line ratios at these positions and apply Local Thermal Equilibrium (LTE) and non-LTE analysis methods in order to derive physical parameters such as masses, densities and temperatures. The CO line emission has been modeled up to J=20. From non-LTE modeling of the low- to high-$J$ CO lines we identify two gas components, a cold one at temperatures of T$_\RM{kin}\sim 30-40$ K, and one with T$_\RM{kin}\sim 80-150$ K at a local clump density of about n(H$_2$)$\sim 10^4-10^6$ cm$^{-3}$. While the cold quiescent component is massive containing typically more than 94 % of the mass, the warm, dense, and turbulent gas is dominated by mid- and high-$J$ CO line emission and its large line widths. The medium must be clumpy with a volume-filling of a few percent. The CO lines are found to be important for the cooling of the cold molecular gas, e.g. at DR21 (OH). Near the outflow of the UV-heated source DR21, the gas cooling is dominated by line emission of atomic oxygen and of CO.
dc.language.isoen
dc.publisherEDP Sciences
dc.subject.enISM: clouds
dc.subject.enISM: abundances
dc.subject.enRadio lines: ISM
dc.subject.enLine: profiles
dc.subject.enStars: formation
dc.subject.enISM: individual objects: DR21
dc.subject.enDR21 (OH)
dc.title.enThe cooling of atomic and molecular gas in DR21
dc.typeArticle de revue
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Cosmologie et astrophysique extra-galactique [astro-ph.CO]
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]
dc.identifier.arxivastro-ph/0609559
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.page999-1012
bordeaux.volume461
bordeaux.peerReviewedoui
hal.identifierhal-00119895
hal.version1
hal.popularnon
hal.audienceNon spécifiée
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00119895v1
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Astronomy%20and%20Astrophysics%20-%20A&A&rft.date=2007&rft.volume=461&rft.spage=999-1012&rft.epage=999-1012&rft.eissn=0004-6361&rft.issn=0004-6361&rft.au=JAKOB,%20H.&KRAMER,%20C.&SIMON,%20R.&SCHNEIDER,%20N.&OSSENKOPF,%20V.&rft.genre=article


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