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Title: Early hydrodynamic evolution of a stellar collision

Abstract

The early phase of the hydrodynamic evolution following the collision of two stars is analyzed. Two strong shocks propagate from the contact surface and move toward the center of each star at a velocity that is a small fraction of the velocity of the approaching stars. The shocked region near the contact surface has a planar symmetry and a uniform pressure. The density vanishes at the (Lagrangian) surface of contact, and the speed of sound diverges there. The temperature, however, reaches a finite value, since as the density vanishes, the finite pressure is radiation dominated. For carbon-oxygen white dwarf (CO WD) collisions, this temperature is too low for any appreciable nuclear burning shortly after the collision, which allows for a significant fraction of the mass to be highly compressed to the density required for efficient {sup 56}Ni production in the detonation wave that follows. This property is crucial for the viability of collisions of typical CO WD as progenitors of type Ia supernovae, since otherwise only massive (>0.9 M {sub ☉}) CO WDs would have led to such explosions (as required by all other progenitor models). The divergence of the speed of sound limits numerical studies of stellar collisions, asmore » it makes convergence tests exceedingly expensive unless dedicated schemes are used. We provide a new one-dimensional Lagrangian numerical scheme to achieve this. A self-similar planar solution is derived for zero-impact parameter collisions between two identical stars, under some simplifying assumptions (including a power-law density profile), which is the planar version of previous piston problems that were studied in cylindrical and spherical symmetries.« less

Authors:
;  [1]
  1. Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
Publication Date:
OSTI Identifier:
22357081
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 785; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COLLISIONS; CONVERGENCE; DENSITY; DETONATION WAVES; HYDRODYNAMICS; IMPACT PARAMETER; LAGRANGIAN FUNCTION; MASS; NICKEL 56; NUMERICAL ANALYSIS; OXYGEN; SOUND WAVES; SPHERICAL CONFIGURATION; SUPERNOVAE; SURFACES; SYMMETRY; VELOCITY; WHITE DWARF STARS

Citation Formats

Kushnir, Doron, and Katz, Boaz. Early hydrodynamic evolution of a stellar collision. United States: N. p., 2014. Web. doi:10.1088/0004-637X/785/2/124.
Kushnir, Doron, & Katz, Boaz. Early hydrodynamic evolution of a stellar collision. United States. https://doi.org/10.1088/0004-637X/785/2/124
Kushnir, Doron, and Katz, Boaz. 2014. "Early hydrodynamic evolution of a stellar collision". United States. https://doi.org/10.1088/0004-637X/785/2/124.
@article{osti_22357081,
title = {Early hydrodynamic evolution of a stellar collision},
author = {Kushnir, Doron and Katz, Boaz},
abstractNote = {The early phase of the hydrodynamic evolution following the collision of two stars is analyzed. Two strong shocks propagate from the contact surface and move toward the center of each star at a velocity that is a small fraction of the velocity of the approaching stars. The shocked region near the contact surface has a planar symmetry and a uniform pressure. The density vanishes at the (Lagrangian) surface of contact, and the speed of sound diverges there. The temperature, however, reaches a finite value, since as the density vanishes, the finite pressure is radiation dominated. For carbon-oxygen white dwarf (CO WD) collisions, this temperature is too low for any appreciable nuclear burning shortly after the collision, which allows for a significant fraction of the mass to be highly compressed to the density required for efficient {sup 56}Ni production in the detonation wave that follows. This property is crucial for the viability of collisions of typical CO WD as progenitors of type Ia supernovae, since otherwise only massive (>0.9 M {sub ☉}) CO WDs would have led to such explosions (as required by all other progenitor models). The divergence of the speed of sound limits numerical studies of stellar collisions, as it makes convergence tests exceedingly expensive unless dedicated schemes are used. We provide a new one-dimensional Lagrangian numerical scheme to achieve this. A self-similar planar solution is derived for zero-impact parameter collisions between two identical stars, under some simplifying assumptions (including a power-law density profile), which is the planar version of previous piston problems that were studied in cylindrical and spherical symmetries.},
doi = {10.1088/0004-637X/785/2/124},
url = {https://www.osti.gov/biblio/22357081}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 785,
place = {United States},
year = {Sun Apr 20 00:00:00 EDT 2014},
month = {Sun Apr 20 00:00:00 EDT 2014}
}