Herschel Observations Of Isolated Star-forming Clouds: Dust-temperature Maps, Dust Properties And Molecular Freezeout
Abstract
Herschel scan map observations, when combined with ground-based submm continuum and NIR extinction data, have the power to observationally constrain the dust properties in molecular clouds at a level where only model assumptions or lab measurements were available in the past. As part of the EPoS (Early Phases of Star Formation) Key Programme, we have selected a sample of sources that is ideal for taking full advantage of the unique capabilities: our sources are well-characterized nearby, isolated small molecular clouds, selected to be in regions with exceptionally low cirrus confusion noise. The excellent spectral sampling of the Herschel measurements enable a detailed comparison of dust properties, such as submm/FIR emissivity vs. NIR extinction. We show what is needed to derive spatially resolved reliable dust temperature maps, and how these very accurate temperature constraints affect the resulting (column) density profiles. Using the example of Barnard 335, a prototypical Class 0 protostar in an isolated Bok globule, we show how external heating by the interstellar radiation field, cooling by dust at high column densities, and internal heating by the embedded protostar affect the temperature structure of the cloud. A comparison between our dust-temperature and column density maps and previous molecular observations reveals important molecular freezeout threshholds and the physical properties at the interface between the cloud envelope and the molecular outflow.
- Publication:
-
American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011
- Bibcode:
- 2011AAS...21720203S