Molecular clouds on the threshold of star formation - The radial density profile of the cores of the Rho Ophiuchi and R Coronae Australis clouds

Details Molecular clouds on the threshold of star formation - The radial density profile of the cores of the Rho Ophiuchi and R Coronae Australis clouds Molecular clouds on the threshold of star formation - The radial density profile of the cores of the Rho Ophiuchi and R Coronae Australis clouds

Jul 1983

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1983apj...270..620l&link_type=abstract

Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 270, July 15, 1983, p. 620-640. Research supported by the Naturvetenskaplig

Astronomy and Astrophysics

Astrophysics

75

Molecular Clouds, Ophiuchi Clouds, Star Formation, Astronomical Catalogs, Astronomical Models, Interstellar Matter, Millimeter Waves, Molecular Spectroscopy, Stellar Spectrophotometry

Scientific paper

In a cold, dense, dynamically evolved cloud core that lacks embedded massive stars, the density distribution should reflect a stage of cloud evolution at the threshold of star formation. The radial density distribution in three such dense massive cores, located within two nearby regions of recent star formation, has been determined from extensive maps of two H2CO transitions. The appearance of the maps of emission and absorption of the 2 cm line confirms the predictions of models for the excitation of this transition. Detailed models of the H2CO radiative transport demonstrate that a rapid radial decline of density, ρ(R) ∝ R-3/2 to R-2, from a density of 106 in the core to l0 cm-3 in the envelope, occurs over radial distances from 0.06 to 0.60 pc. These models require a decline in H2CO abundance with increasing density in these cold cores, perhaps a result of condensation of gas onto grains. For the observed values of core radius (0.06-0.09 pc) and core mass (19-110 Msun), the H2CO line widths indicate that the velocity dispersion due to rotation or turbulence is too small to stabilize the cloud against gravitational collapse. The observed magnetic field strength also appears to be inadequate to prevent cloud contraction and eventual star formation.
The unusual 2 cm H2CO emission toward ρ Oph B is found to be spatially extended (8' × 4'). The lack of far-infrared emission from this cold dense (>106 cm-3) region indicates a lack of stars of high luminosity embedded within or near the surface of the cloud. The combination of cold, very dense gas in a centrally condensed region together with a lack of internal support means that within ρ Oph B the stage has been set for the possible formation of one or more massive protostars.

Affiliated with

Also associated with

No associations

Rating

Molecular clouds on the threshold of star formation - The radial density profile of the cores of the Rho Ophiuchi and R Coronae Australis clouds does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Molecular clouds on the threshold of star formation - The radial density profile of the cores of the Rho Ophiuchi and R Coronae Australis clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Molecular clouds on the threshold of star formation - The radial density profile of the cores of the Rho Ophiuchi and R Coronae Australis clouds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1627161