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Title: GLOBAL NON-SPHERICAL OSCILLATIONS IN THREE-DIMENSIONAL 4π SIMULATIONS OF THE H-INGESTION FLASH

We performed three-dimensional simulations of proton-rich material entrainment into {sup 12}C-rich He-shell flash convection and the subsequent H-ingestion flash that took place in the post-asymptotic giant branch star Sakurai's object. Observations of the transient nature and anomalous abundance features are available to validate our method and assumptions, with the aim of applying them to very low-metallicity stars in the future. We include nuclear energy feedback from H burning and cover the full 4π geometry of the shell. Runs on 768{sup 3} and 1536{sup 3} grids agree well with each other and have been followed for 1500 minutes and 1200 minutes. After an 850 minute long quiescent entrainment phase, the simulations enter into a global non-spherical oscillation that is launched and sustained by individual ignition events of H-rich fluid pockets. Fast circumferential flows collide at the antipode and cause the formation and localized ignition of the next H-overabundant pocket. The cycle repeats for more than a dozen times while its amplitude decreases. During the global oscillation, the entrainment rate increases temporarily by a factor of ≈100. Entrained entropy quenches convective motions in the upper layer until the burning of entrained H establishes a separate convection zone. The lower-resolution run hints atmore » the possibility that another global oscillation, perhaps even more violent, will follow. The location of the H-burning convection zone agrees with a one-dimensional model in which the mixing efficiency is calibrated to reproduce the light curve. The simulations have been performed at the NSF Blue Waters supercomputer at NCSA.« less
Authors:
 [1] ; ; ;  [2] ;  [3]
  1. Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P5C2 (Canada)
  2. LCSE and Department of Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)
  3. Computational Computer Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
Publication Date:
OSTI Identifier:
22365235
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 792; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; ASYMPTOTIC SOLUTIONS; CARBON 12; COMPUTERIZED SIMULATION; CONVECTION; EFFICIENCY; ENTROPY; FEEDBACK; GIANT STARS; HYDRODYNAMICS; METALLICITY; OSCILLATIONS; PROTONS; RESOLUTION; SPHERICAL CONFIGURATION; THREE-DIMENSIONAL CALCULATIONS; TRANSIENTS; VISIBLE RADIATION