Dense cores in dark clouds. II. NH/sub 3/ observations and star formation

Journal Article · Tue Mar 01 04:00:00 EST 1983 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160780· OSTI ID:6239902

Myers, P C; Benson, P J

We present partial results of a survey of approx.100 visually opaque regions in nearby dark clouds in the 1.3 cm (J,K) = (1,1) line of NH/sub 3/, with mapping of all strong sources (''dense cores'') and (2,2) line observations in selected positions. For 27 dense cores with distance estimates, mean properties are: FWHM diameter, 0.1 pc; density, 3 x 10/sup 4/ cm/sup -3/; mass, 4 M/sub sun/; kinetic temperature, 11 K; and FWHM velocity width, 0.3 km s/sup -1/. We compare line shapes with cloud motion models, and source density, size, and temperature with equilibrium and stability requirements. These indicate that most dense cores are in the early stages of collapse or in near-critical equilibrium; if in equilibrium, they are probably supported by a combination of thermal and subsonic turbulent motions. In Taurus-Auriga, positions of the 10 known dense cores are well correlated with positions of emission-line star groups. In the next dense core free-fall time, 2 x 10/sup 5/ yr, the Taurus-Auriga complex is expected to form 25--50 emission-line stars. This is consistent with the estimated number of dense cores, 25. Taken together, these results suggest that most of the dense cores described here will form low-mas stars in the next approx.10/sup 6/ yr.

• Research Organization: Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology
• OSTI ID: 6239902
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 266:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMMONIA
EMISSION SPECTRA
GRAVITATIONAL COLLAPSE
HYDRIDES
HYDROGEN COMPOUNDS
INTERSTELLAR GRAINS
LINE WIDTHS
NEBULAE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
PARTICLES
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STARS
VARIABLE STARS