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2000AJ....120..393C - Astron. J., 120, 393-406 (2000/July-0)

Morphology and energetics of the molecular gas within a core and a diffuse region in the filamentary dark cloud GF 9.


Abstract (from CDS):

We have performed a CO, 13CO, and CS survey of a dense core region (GF 9-Core) and a diffuse filamentary region (GF 9-Fila) within the dark cloud GF 9 (LDN 1082). Spectra in each line were obtained toward 120 positions within each region covering areas of 8'x10'. GF 9-Core is associated with the Class 0 protostar IRAS PSC 20503+6006, while GF 9-Fila has no associated IRAS point sources. The median CO excitation temperature of the core region is 7.2±0.5 K; for the filament region, the median temperature is 7.8±0.5 K. The mass derived from the LTE isothermal analysis of 13CO is 53±8 and 40±6 M for GF 9-Core and GF 9-Fila, respectively. Using near-infrared extinction data to trace the H2 column density, the isothermal LTE assumptions for 13CO appear to break down at AV≳3 mag. The near-infrared extinction data are used to correct the derived 13CO column densities, yielding mass estimates that are ∼20% larger than the LTE-derived masses. The average H2 volume densities for GF 9-Core and GF 9-Fila are ∼5000±700 and ∼1700±200 cm–3. Each region contains a 15±3 M centrally condensed CS core, which is approximately 3 times more dense than the ambient 13CO regions. In GF 9-Core, the high-density gas core appears to be physically associated with the IRAS point source. Both high-density cores appear to be in virial equilibrium; however, the CS line widths in GF 9-Core are almost twice as large as those measured in GF 9-Fila. Because GF 9-Core is associated with the Class 0 protostar PSC 20503+6006, the CS line widths may be enhanced by outflow or infall motion. The additional nonturbulent line-broadening component caused by outflow/infall motion required to explain the line width implies a supersonic velocity of at least 0.3 km.s–1 (Mach 1.5).

Abstract Copyright:

Journal keyword(s): ISM: Abundances - ISM: Clouds - ISM: Individual: Alphanumeric: LDN 1082 - ISM: Individual: Alphanumeric: GF 9 - ISM: Kinematics and Dynamics - Stars: Formation

Simbad objects: 3

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