Nature of bipolar sources in dense molecular clouds

Journal Article · Fri Oct 01 04:00:00 EDT 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160324· OSTI ID:6423335

Koenigl, A

A unified interpretation is presented of bipolar sources associated with young stellar objects which are embedded in dense molecular clouds. It is suggested that such phenomena as optical and radio ''jets,'' high-proper-motion Herbig-Haro objects, separating broad-wing CO emission-line lobes, and cometary and bipolar nebulae, are linked through a basic outflow mechanism which is manifested on different scales. The outflow is assumed to originate in a spherically symmetric stellar wind which expands in a medium with anisotropic density and pressure distributions. The wind creates an interstellar bubble which elongates in the direction of the steepest external density gradient. The shape of the evacuated cavity is calculated explicitly for an energy-driven bubble and a power-law density distribution. It is shown that for density distributions which are likely to exist in protostellar environments, the expanding bubble could become unstable to the formation of de Laval nozzles which channel the flow into two oppositely directed, supersonic jets. The structure of nozzles and of jets is discussed in relation to various morphological features of bipolar sources. In particular, certain wave phenomena in jets, which could be induced by variations in the external pressure distribution, are applied to the interpretation of fan-shaped cometary nebulae and of certain stationary Herbig-Haro objects. Theoretical advantages of a directed-outflow model for bipolar sources are considered, and the reievance of molecular cloud jets to the study of jets in other astrophysicl environments is briefly outlined.

• Research Organization: Astronomy Department, University of California, Berkeley
• OSTI ID: 6423335
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 261:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
COSMIC DUST
COSMIC GASES
DUSTS
EMISSION
EXPANSION
FLUID FLOW
FLUID MECHANICS
FLUIDS
GASES
HYDRODYNAMICS
INTERSTELLAR GRAINS
INTERSTELLAR MAGNETIC FIELDS
JETS
MAGNETIC FIELDS
MECHANICS
NEBULAE
NOZZLES
PARTICLES
SHOCK WAVES
STARS
STELLAR WINDS
SUPERSONIC FLOW