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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448253.0, MPI für Astronomie / Publikationen_mpia
Submillimeter observations of the quiescent core---Ophiuchus A-N6
Authors:Pon, A.; Plume, R.; Friesen, R. K.; Di Francesco, J.; Matthews, B.; Bergin, E. A.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Start Page:1914
End Page:1923
Review Status:not specified
Audience:Experts Only
Abstract / Description:We have observed the Oph A-N6 prestellar core in the following transitions: N2D+ J= 3 --> 2, DCO+ J= 3 --> 2 and J= 5 --> 4, HCO+ J= 3 --> 2, CS J= 5 --> 4 and J= 7 --> 6, and H13CO+ J= 3 --> 2 and J= 4 --> 3, using the James Clerk Maxwell Telescope. We also observed the NH3 (1, 1) and (2, 2) inversion transitions toward the Oph A-N6 peak with the Green Bank Telescope. We have found that the N6 core is composed of shells of different chemical composition due to the freezing out of chemical species at different densities. The undepleted species N2D+ appears to trace the high-density interior of the core, DCO+ and H13CO+ trace an intermediate region, and CS traces the outermost edges of the core. A distinct blue-red spectral asymmetry, indicative of infall motion, is clearly detected in the HCO+ spectra, suggesting that N6 is undergoing gravitational collapse. This collapse was possibly initiated by a decrease in turbulent support suggested by the fact that the nonthermal contribution to the line widths is smaller for the molecular species closer to the center of the core. We also present a temperature profile for the core. These observations support the claim that the Oph A-N6 core is an extremely young prestellar core, which may have been recently cutoff from magnetohydrodynamic support and begun to collapse.
Free Keywords:ISM: clouds; ISM: molecules; stars: formation
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009ApJ...698.1914P [ID No:1]
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