Mixing in ejecta of supernovae. I - General properties of two-dimensional Rayleigh-Taylor instabilities and mixing width in ejecta of supernovae

Abstract

view Abstract Citations (53) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Mixing in Ejecta of Supernovae. I. General Properties of Two-dimensional Rayleigh-Taylor Instabilities and Mixing Width in Ejecta of Supernovae Hachisu, Izumi ; Matsuda, Takuya ; Nomoto, Ken'ichi ; Shigeyama, Toshikazu Abstract Nonlinear growth of two-dimensional Rayleigh-Taylor (R-T) instabilities are numerically studied to apply to the mixing in the supernova ejecta. We first present much refined calculations of mixing in the realistic model of SN 1987A with a better code and various mesh resolutions. The results show that the mixing width (or the extent of mixing) due to Rayleigh-Taylor instabilities is still too small to account for the observations even with relatively large initial perturbation. The mixing width is found to depend only slightly on the mesh resolution when the initial amplitude is larger than ~5% of the expansion speed. To clarify the basic properties of the R-T instabilities and the dependence of the mixing width on the initial density structure, initial perturbation, and numerical resolution, we consider much simplified ideal models of R-T instabilities of compressible gas with an adiabatic constant γ = 4/3. The ideal R-T instabilities are calculated for various mesh resolutions, the numerical accuracy (second-order and third- order), the density ratio, the initial amplitude of the perturbations, and the mode of the initial perturbation (random from mesh to mesh and sinusoidal waves). It is found that when the initial amplitude of the velocity perturbation is larger than 1% of the sound speed, the mixing width in time depends hardly on the mesh resolution, numerical accuracy, or the mode of the initial perturbation. The mixing width depends mainly on the initial amplitudes and the density ratio. This suggests that the mixing width in the supernova ejecta depends mainly on the initial amplitude of the perturbation and on the density structure of the presupernova models (density ratio), which confirm the results on the real mixing in ejecta of SN 1987A. Publication: The Astrophysical Journal Pub Date: May 1992 DOI: 10.1086/171274 Bibcode: 1992ApJ...390..230H Keywords: Ejecta; Hydrodynamics; Stellar Interiors; Supernova 1987a; Taylor Instability; Computational Astrophysics; Mixing; Scaling Laws; Astrophysics full text sources ADS | data products SIMBAD (1) NED (1) Related Materials (1) Part 2: 1994A&AS..104..341H