NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
A numerical study of the effects of ambipolar diffusion on the collapse of magnetic gas cloudsThe gravitational collapse of isothermal, nonrotating magnetic gas clouds have been calculated numerically, including the effects of ambipolar diffusion. The fractional ionization in the clouds is approximated by a power-law function of the gas density, f = K/n to the q-power, where K and q are adjustable parameters. Eleven numerical experiments were run, and the results indicate that the asymptotic character of collapse is determined mainly by the value of q and is largely independent of the other parameters characterizing a cloud (e.g., K, cloud mass). In particular, there is nearly a one-to-one correspondence between q and the slope, x, of the central magnetic field strength-gas density relationship. If q is no more than 0.8, a cloud collapses asymptotically, as though the magnetic field were 'frozen' to the neutral matter. The magnetic field strength at the center of a collapsing cloud is strongly amplified during collapse even for values of q of about 1, despite extremely low values of fractional ionization. A discussion of the theoretical basis for this unexpected behavior is given. Possible implications of our results for the problems of magnetic braking of rotating protostars and star formation in general are also presented.
Document ID
19830035779
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Black, D. C.
(NASA Ames Research Center Moffett Field, CA, United States)
Scott, E. H.
(NASA Ames Research Center Space Science Div., Moffett Field, CA, United States)
Date Acquired
August 11, 2013
Publication Date
December 15, 1982
Publication Information
Publication: Astrophysical Journal
Subject Category
Astrophysics
Accession Number
83A16997
Funding Number(s)
CONTRACT_GRANT: NAS2-10651
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available