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Self-gravity and dissipation in polar ringsStudies of inclined rings inside galaxy potentials have mostly considered the influence of self-gravity and viscous dissipation separately. In this study, we construct models of highly inclined ('polar') rings in an external potential including both self-gravity and dissipation due to a drag force. We do not include pressure forces and thus ignore shock heating that dominates the evolution of gaseous rings inside strongly nonspherical potentials. We adopt an oblate spheroidal scale-free logarithmic potential with axis ratio q = 0.85 and an initial inclination of 80 deg for the self-gravitating rings. We find that stellar (dissipationless) rings suffer from mass loss during their evolution. Mass loss also drives a secular change of the mean inclination toward the poles of the potential. As much as half of the ring mass escapes in the process and forms an inner and an outer shell of precessing orbits. If the remaining mass is more than approximately 0.02 of the enclosed galaxy mass, rings remain bound and do not fall apart from differential precession. The rings precess at a constant rate for more than a precession period tau(sub p) finding the configuration predicted by Sparke in 1986 which warps at larger radii toward the poles of the potential. We model shear viscosity with a velocity-dependent drag force and find that nuclear inflow dominates over self-gravity if the characteristic viscous inflow time scale tau(sub vi) is shorter than approximately 25(tau(sub p)). Rings with (tau(sub vi))/(tau(sub p)) less than or approximately equal to 25 collapse toward the nucleus of the potential within one precession period independent of the amount of self-gravity. Our results imply that stars and gas in real polar rings exhibit markedly different dynamical evolutions.
Document ID
19950053094
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Dubinski, John
(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA United States)
Christodoulou, Dimitris M.
(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA United States)
Date Acquired
August 16, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 424
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A84693
Funding Number(s)
CONTRACT_GRANT: NSF AST-91-48279
CONTRACT_GRANT: NAGW-1510
Distribution Limits
Public
Copyright
Other

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