# 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 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

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Peer reviewed scholarly articles from the Faculty of Arts and Sciences of Harvard University