Evolution of star-bearing molecular clouds: the high-velocity HCO/sup +/ flow in NGC 2071

Journal Article · Sun Apr 15 04:00:00 EST 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/161927· OSTI ID:6861071

Wootten, A; Loren, R B; Sandqvist, A; Friberg, P; Hjalmarson, =; Hjalmarson, =

The J = 1-0 and J = 302 lines of HCO/sup +/ and H/sup 13/CO/sup +/ have been observed in the molecular cloud NGC 2071, where they map the dense portions of a bidirectional molecular flow. The high resolution (42'') of our observations has enabled us to determine the distribution of mass, momentum , and energy in the flow as a function of projected distance from the cluster. Both momentum and energy diminish with distance from the central cluster of infrared sources. The highest velocities at a given intensity in this dense flow occur in a limited region coincident with an infrared cluster and the densest part of the molecular cloud. Higher resolution (33'') CO and /sup 13/CO observations reveal that the extreme velocities in the flow occur in regions displaced on opposite sides of the cluster, suggesting that the flow only becomes visible in molecular line emission at distances approx.0.1 pc from its supposed source. Lower velocity material containing most of the mass of the flow is found over larger regions, as expected if the flow has decelerated as it has evolved. Assuming conservation of momentum, the historical rate of momentum injection is found to have been roughly constant over a period of 10/sup 4/ years, suggesting a constancy of the average luminosity of the central cluster over that time. The J = 3--2 HCO/sup +/ profile does not show the absorption which is a prominent feature of the J = 1--0 profile, and the J = 3--2 line appears to be a useful probe of conditions specific to the dense cores of clouds. The high velocity HCO/sup +/ emission correlates very well with spatial and velocity events of molecular hydrogen emission. The abundance of HCO/sup +/(X(HCO/sup +/)approx.10/sup -8/), and by inference the electron density, is similar in material at all velocities.

• Research Organization: Department of Physics, Rensselaer Polytechnic Institute
• OSTI ID: 6861071
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 279:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ACYL RADICALS
DISTRIBUTION
EMISSION
ENERGY-LEVEL TRANSITIONS
FLUID FLOW
FORMYL RADICALS
INTERSTELLAR GRAINS
IONIZATION
MAPS
NEBULAE
PARTICLES
RADIAL VELOCITY
RADICALS
SPATIAL DISTRIBUTION
SPECTRA
STAR ACCRETION
STAR EVOLUTION
VELOCITY