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The COordinated Molecular Probe Line Extinction Thermal Emission Survey of Star Forming Regions

Comparing Column Density Tracers in Molecular Clouds

Alyssa Goodman, Scott Schnee, Naomi Ridge

Publications

Scott L. Schnee, T. Bethell, Alyssa A. Goodman, "Estimating Column Density in Molecular Clouds Using Far-IR and Sub-mm Emission Maps", 2006, ApJ, 640, L47. .

Scott L. Schnee, Naomi A. Ridge, Alyssa A. Goodman, Jason G. Li, "A COMPLETE Look at the use of IRAS Emission Maps to Estimate Extinction and Dust Temperature". 2005, ApJ, 634, 442.

Figure
Intercomparison of column density maps

Intercomparison of column density maps based on 13CO integrated intensity, far-infrared dust emission, and near-infrared extinction mapping reveals that: extinction mapping is most intrinsically accurate; far-infrared emission maps can be custom-corrected to nearly match extinction maps (see panel at right); but 13CO maps cannot be corrected to represent column density faithfully. The 13CO emission is subject to both opacity and depletion effects at high column densities, and is sub-thermally excited at low column density, leading to column density maps that are impressionistically, but not quantitatively, accurate. The near-infrared and thermal emission maps show that, at least over the 10-square pc area of Perseus mapped in COMPLETE, the distribution of column density is log-normal, as predicted by many theories of turbulence.