NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Thin shell formation in radiative shocks. 1: Supernova remnants in low-density mediaThis paper explores the onset of thin-shell formation in interstellar shocks associated with supernova explosions. We outline a simple but useful scheme that indicates the time at which thin shell formation begins for supernova remnants (SNRs) evolving in a range of interstellar environments, extending the previous analytical models to arbitrary power-law density media. The result depends on the gas cooling properties and the shock velocity and radius. This is then applied to the specific case of SNRs in low-density media. The procedure for defining the time for the onset of shell formation, t(sub sf), equates the value of the adiabat, kappa = p/rho(exp gamma), to zero using the known time dependence of the shock radius and velocity. For the case of a power-law density ambient medium of the form rho(r) = Br(exp -omega), it is found that shell formation can be prevented when the ambient density drops faster than a critical rate. For a cooling function of the form Lambda = Lambda(sub 0) tau(exp beta), with beta = -0.5 (appropriate for line cooling), shell formation never occurs for omega greater than or equal to 9/5. The shell formation time is then computed for spherical shocks in a power-law density medium. For omega = 0, the onset of shell formation is found to be at t(sub sf) approx. equal to 2.87 x 10(exp 4) E51(exp 3/14) n(sub 0 exp -4.7) yr, which agrees well with previous estimates derived by other means. We compare the analytical shell formation time with the results of detailed numerical models for omega = 0 and three different ambient densities and find good agreement. The extension of the criterion for the onset of thin shell formation using the ratio of cooling to swept-up column density is also described. This method provides a useful approximation for cases when the exact solution is not known.
Document ID
19950038837
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Franco, Jose
(Univ. Nacional Autonoma de Mexico Mexico)
Miller, Walter Warren, III
(Univ. of Wisconsin-Madison, Madison, WI United States)
Arthur, S. J.
(Univ. Nacional Autonoma de Mexico Mexico)
Tenorio-Tagle, Guillermo
(Instituto de Astrofisica de Canarias Tenerife, Spain)
Terlevich, Roberto
(Royal Greenwich Observatory Cambridge, United Kingdom)
Date Acquired
August 16, 2013
Publication Date
November 10, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 435
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A70436
Funding Number(s)
CONTRACT_GRANT: EEC-CI1-CT91-0935
CONTRACT_GRANT: NAGW-2532
CONTRACT_GRANT: NAG5-629
Distribution Limits
Public
Copyright
Other

Available Downloads

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