Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010aas...21535501p&link_type=abstract
American Astronomical Society, AAS Meeting #215, #355.01; Bulletin of the American Astronomical Society, Vol. 42, p.538
Astronomy and Astrophysics
Astronomy
Scientific paper
Molecular clouds have been known for years to show supersonic line-widths. Also, numerical simulations of supersonic turbulence have shown a relative success on explaining some of their observed properties. However, these molecular cloud are still quite successful at forming coherent dense cores, where their non-thermal motions appear subsonic (see Goodman el al. 1998, Caselli et al. 2002, Rosolowsky et al. 2008, Rathborne et al. 2008, Kirk et al. 2009).
In this talk we present the results from mapping four star-forming regions with the Green Bank Telescope (GBT) in NH3(1,1) and (2,2). These regions (all located in the Perseus Molecular Cloud) present different levels of star-formation activity and also differ in their proximity to the nearest cluster. We show the detection, for the first time, of the transition between dense but turbulent gas and the coherent dense core. The constrains on numerical simulations are also disscused.
Thanks to the sensitivity provided by the GBT, a comparison of the emission between two commonly used dense gas tracers (NH3 and dust emission) is presented. The spatial distribution of some of the physical parameters obtained from fitting the NH3 lines are presented (e.g. velocity dispersion, kinetic and excitation temperatures, column and volume densities) and compared with the pointed observations in Perseus (Rosolowsky et al. 2008 and Foser et al. 2009). At the light of this discussion, we argue that the mapping of dense cores is a crucial completment for the pointed observations.
J. E. P. is supported by a grant from the NRAO Student Observing Support Program (GSSP06-0015 and GSSP08-0031), and also by the National Science Foundation through grant #AF002 from the Association of Universities for Research in Astronomy, Inc., under NSF cooperative agreement AST-9613615 and by Fundación Andes under project No. C-13442.
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