Gravitational instabilities in shearing, magnetic galaxies with a cloudy interstellar gas
1989; IOP Publishing; Volume: 342; Linguagem: Inglês
10.1086/185486
ISSN1538-4357
Autores Tópico(s)Solar and Space Plasma Dynamics
Resumoview Abstract Citations (23) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Gravitational Instabilities in Shearing, Magnetic Galaxies with a Cloudy Interstellar Gas Elmegreen, Bruce G. Abstract A cloudy interstellar medium in a galactic disk with rotation, shear, and an azimuthal magnetic field is found to be gravitationally unstable on all length scales down to the cloud collision mean free path. Most instabilities are not transient, but grow exponentially without limit. The magnetic field overcomes the Coriolis force, and the dissipation from cloud collisions effectively removes the pressure. The collapse occurs at about the conventional Jeans rate for masses between 10^3^ M_sun_ and 10^7^ M_sun_. If the probability for collapse on a particular scale is proportional to the collapse rate on that scale, then a M^-1.5^ mass spectrum results. Gravitational instabilities should occur continuously in the ambient medium, and have an enhanced rate in spiral density wave crests and swept-up shells. They readily account for the formation of most self-gravitating clouds in spiral galaxies and could be the single most important event that initiates star formation. Publication: The Astrophysical Journal Pub Date: July 1989 DOI: 10.1086/185486 Bibcode: 1989ApJ...342L..67E Keywords: Gravitational Collapse; Interstellar Gas; Interstellar Magnetic Fields; Molecular Clouds; Coriolis Effect; Interstellar Matter; Perturbation Theory; Shock Waves; Star Formation; Astrophysics; GRAVITATION; INSTABILITIES; STARS: FORMATION full text sources ADS |
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