Direct Observation of a Sharp Transition to Coherence in Dense Cores

Direct Observation of a Sharp Transition to Coherence in Dense Cores

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Direct Observation of a Sharp Transition to Coherence in Dense Cores

dc.contributor.author	Pineda, Jaime Eduardo
dc.contributor.author	Goodman, Alyssa A.
dc.contributor.author	Caselli, Paola
dc.contributor.author	Foster, Jonathan B.
dc.contributor.author	Myers, Philip C.
dc.contributor.author	Rosolowsky, Erik W.
dc.contributor.author	Arce, Hector G.
dc.date.accessioned	2011-02-07T14:41:01Z
dc.date.issued	2010
dc.identifier.citation	Jaime, E. Pineda, Alyssa A. Goodman, Hector G. Arce, Paola Caselli, Jonathan B. Foster, Philip C. Myers, and Erik W. Rosolowsky. 2010. Direct observation of a sharp transition to coherence in dense cores. The Astrophysical Journal Letters 712(1): L116-L121.	en_US
dc.identifier.issn	2041-8205	en_US
dc.identifier.uri	http://nrs.harvard.edu/urn-3:HUL.InstRepos:4706182
dc.description.abstract	We present \(NH_3\) observations of the B5 region in Perseus obtained with the Green Bank Telescope. The map covers a region large enough \((\sim 11'×14')\) that it contains the entire dense core observed in previous dust continuum surveys. The dense gas traced by \(NH_{3}(1,1)\) covers a much larger area than the dust continuum features found in bolometer observations. The velocity dispersion in the central region of the core is small, presenting subsonic non-thermal motions which are independent of scale. However, it is because of the coverage and high sensitivity of the observations that we present the detection, for the first time, of the transition between the coherent core and the dense but more turbulent gas surrounding it. This transition is sharp, increasing the velocity dispersion by a factor of 2 in less than 0.04 pc (the 31'' beam size at the distance of Perseus,\(\sim 250 pc)\). The change in velocity dispersion at the transition is \( \approx 3 km \ s^{-1} \ pc^{–1}\). The existence of the transition provides a natural definition of dense core: the region with nearly constant subsonic non-thermal velocity dispersion. From the analysis presented here, we can neither confirm nor rule out a corresponding sharp density transition.	en_US
dc.description.sponsorship	Astronomy	en_US
dc.description.sponsorship	Other Research Unit	en_US
dc.language.iso	en_US	en_US
dc.publisher	American Astronomical Society	en_US
dc.relation.isversionof	doi:10.1088/2041-8205/712/1/L116	en_US
dc.relation.hasversion	http://arxiv.org/abs/1002.2946v1	en_US
dash.license	OAP
dc.subject	From Astrophysical Journal Letters:	en_US
dc.subject	ISM: clouds	en_US
dc.subject	ISM: individual objects (B5, Perseus Molecular Complex)	en_US
dc.subject	ISM: molecules	en_US
dc.subject	stars: formation	en_US
dc.title	Direct Observation of a Sharp Transition to Coherence in Dense Cores	en_US
dc.type	Journal Article	en_US
dc.description.version	Author's Original	en_US
dc.relation.journal	The Astrophysical Journal Letters	en_US
dash.depositing.author	Goodman, Alyssa A.
dc.date.available	2011-02-07T14:41:01Z