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Session 105 - Molecular Cores and Protostars.
Display session, Thursday, January 16
Filamentary structures are expected, from optical polarization studies, to coexist with large scale magnetic fields (e.g. McCutcheon et al. 1986). If self-gravity is important in these filamentary clouds, the clouds are expected to experience gravitational instability and fragment; stars can be formed out of these condensations if the supporting internal energy can be dissipated (e.g., Elmegreen 1985). In an attempt to understand the physical conditions within a molecular cloud just prior to the onset of star formation, we have performed an observational study of two different regions within the filamentary dark cloud GF-9 (LDN 1082) (see Schneider amp; Elmegreen 1979).
We have chosen a representative dense core and diffuse filamentary region for a detailed comparative study. The core is associated with the IRAS point source PSC 20503+6006 and is suspected of being engaged in star formation (Dobashi et al. 1994). The diffuse filamentary region has no IRAS point source associated with it and is likely quiescent. Through a comparison of the two regions, we wish to gain insight into the conditions required in order to produce stars.
At the Five College Radio Astronomy Observatory, the core and filamentary region were observed in the rotational transitions of ^12CO(J=1\rightarrow0), ^13CO(J=1\rightarrow0) and CS(J=2\rightarrow1) covering a region of 10^\prime \times 8^\prime. At the Wyoming Infrared Observatory using the Aerospace Corporation NICMOS3 camera, the core and filament were also imaged in the near-infrared broadband filters J,H and K covering a slightly smaller region of 7^\prime \times 7^\prime. We present a summary and a comparison of the physical parameters (i.e., temperature, density and kinematics) of the molecular gas for the core and filament. We also present visual extinction maps of the core and filament calculated from the H-K excess seen toward infrared sources background to the cloud. Masses are calculated from the dust extinction maps and are compared to the masses calculated from the molecular gas.
Elmegreen, B.G. 1985, in Protostars and Planets II, ed. D. C. Black amp; M. S. Mathews (Tuscon: University of Arizona), 33
Dobashi, K., Bernard, J., Yonekura, Y., amp; Fukui, Y. 1994, ApJS, 95, 419
McCutcheon, W. H., Vrba, F. J., Dickman, R. L. amp; Clemens, D. P. 1986, ApJ, 309, 619
Schneider, S. amp; Elmegreen, B. G. 1979, ApJS, 41, 87
This work has been supported in part by the Wyoming Space Grant Consortium under grant NGT-40050 and the NSF under grant AST94-53354 (University of Wyoming).
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