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dc.contributor.authorPillai, T.
dc.contributor.authorKauffmann, J.
dc.contributor.authorWyrowski, F.
dc.contributor.authorHatchell, J.
dc.contributor.authorGibb, A.G.
dc.contributor.authorThompson, M.A.
dc.date.accessioned2011-06-13T11:09:38Z
dc.date.available2011-06-13T11:09:38Z
dc.date.issued2011
dc.identifier.citationPillai , T , Kauffmann , J , Wyrowski , F , Hatchell , J , Gibb , A G & Thompson , M A 2011 , ' Probing the initial conditions of high-mass star formation II : Fragmentation, stability, and chemistry towards high-mass star-forming regions G29.96-0.02 and G35.20-1.74 ' , Astronomy and Astrophysics , vol. 530 , A118 . https://doi.org/10.1051/0004-6361/201015899
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 162196
dc.identifier.otherPURE UUID: 6fd89435-8321-4d97-8752-3e21287ac114
dc.identifier.otherdspace: 2299/5953
dc.identifier.otherScopus: 79957531802
dc.identifier.urihttp://hdl.handle.net/2299/5953
dc.descriptionOriginal article can be found at: http://www.aanda.org/ Copyright The European Southern Observatory
dc.description.abstractMost work on high-mass star formation has focused on observations of young massive stars in protoclusters. Very little is known about the preceding stage. Here, we present a new high-resolution study of pre-protocluster regions in tracers exclusively probing the coldest and dense gas (NH2D). The two target regions G29.96-0.02 and G35.20-1.74 (W48) are drawn from the SCAMPS project, which searches for pre-protoclusters near known ultracompact HII regions. We used our data to constrain the chemical, thermal, kinematic, and physical conditions (i.e., densities) in G29.96e and G35.20w. NH3, NH2D, HCO+, and continuum emission were mapped using the VLA, PdBI, and BIMA. In particular, NH2D is a unique tracer of cold, precluster gas at high densities, while NH3 traces both the cold and warm gas of modest-to-high densities. In G29.96e, Spitzer images reveal two massive filaments, one of them in extinction (infrared dark cloud). Dust and line observations reveal fragmentation into mul! tiple massive cores strung along filamentary structures. Most of these are cold (<20 K), dense (> 10(5) cm(-3)) and highly deuterated ([NH2D/NH3] > 6%). In particular, we observe very low line widths in NH2D (FWHM less than or similar to 1 km s(-1)). These are very narrow lines that are unexpected towards a region forming massive stars. Only one core in the center of each filament appears to be forming massive stars (identified by the presence of masers and massive outflows); however, it appears that only a few such stars are currently forming (i.e., just a single Spitzer source per region). These multi-wavelength, high-resolution observations of high-mass pre-protocluster regions show that the target regions are characterized by (i) turbulent Jeans fragmentation of massive clumps into cores (from a Jeans analysis); (ii) cores and clumps that are "over-bound/subvirial", i.e. turbulence is too weak to support them against collapse, meaning that (iii) some ! models of monolithic cloud collapse are quantitatively inconsi! stent wi th data; (iv) accretion from the core onto a massive star, which can (for observed core sizes and velocities) be sustained by accretion of envelope material onto the core, suggesting that (similar to competitive accretion scenarios) the mass reservoir for star formation is not necessarily limited to the natal core; (v) high deuteration ratios ([NH2D/NH3] > 6%), which make the above discoveries possible; (vi) and the destruction of NH2D toward embedded stars.en
dc.format.extent19
dc.language.isoeng
dc.relation.ispartofAstronomy and Astrophysics
dc.rightsOpen
dc.subjectastrochemistry
dc.subjectmolecular data
dc.subjectturbulance
dc.subjectISM : clouds
dc.subjectISM : jets and outflows
dc.subjectISM : molecules
dc.titleProbing the initial conditions of high-mass star formation II : Fragmentation, stability, and chemistry towards high-mass star-forming regions G29.96-0.02 and G35.20-1.74en
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionCentre for Astrophysics Research
dc.contributor.institutionScience & Technology Research Institute
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dcterms.dateAccepted2011
rioxxterms.versionVoR
rioxxterms.versionofrecordhttps://doi.org/10.1051/0004-6361/201015899
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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