Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2011-04-19
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
75 pages, 38 figures
Scientific paper
We present observations of HCO+ and H^13CO+, N2H+, HCS+, HCN and HN^13C, SO and ^34SO, CCH, SO_2, and CH_3OH-E towards a sample of 27 high-mass clumps coincident with water maser emission. All transitions are observed with or convolved to nearly identical resolution (30"), allowing for inter-comparison of the clump properties derived from the mapped transitions. We find N2H+ emission is spatially differentiated compared to the dust and the other molecules towards a few very luminous cores (10 of 27) and the N2H+ integrated intensity does not correlate well with dust continuum flux. We calculate the effective excitation density, n_eff, the density required to excite a 1 K line in T_kin=20 K gas for each molecular tracer. The intensity of molecular tracers with larger effective excitation densities (n_eff > 10^5 cm^-3) appear to correlate more strongly with the submillimeter dust continuum intensity. The median sizes of the clumps are anti-correlated with the n_eff of the tracers (which span more than three orders of magnitude). Virial mass is not correlated with n_eff, especially where the lines are optically thick as the linewidths may be broadened significantly by non-virial motions. The median mass surface density and median volume density of the clumps is correlated with n_eff indicating the importance of understanding the excitation conditions of the molecular tracer when deriving the average properties of an ensemble of cores.
Brogan Crystal
Reiter Megan
Shirley Yancy
Tatematsu Ken'ichi
Wootten Alwyn
No associations
LandOfFree
The Physical Properties of High-Mass Star-Forming Clumps: A Systematic Comparison of Molecular Tracers does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Physical Properties of High-Mass Star-Forming Clumps: A Systematic Comparison of Molecular Tracers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Physical Properties of High-Mass Star-Forming Clumps: A Systematic Comparison of Molecular Tracers will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-431686