Hostname: page-component-7479d7b7d-t6hkb Total loading time: 0 Render date: 2024-07-13T18:44:38.175Z Has data issue: false hasContentIssue false
  • English
  • Français

Dynamics of Type-II Supernovae

Published online by Cambridge University Press:  12 April 2016

H.-Th. Janka  and
E. M. Müller
H.-Th. Janka
Affiliation:
Max-Planck-Institut für Astrophysik, Karl-Schwarzshild-Strasse 1, D-8046 Garching, Germany
E. M. Müller
Affiliation:
Max-Planck-Institut für Astrophysik, Karl-Schwarzshild-Strasse 1, D-8046 Garching, Germany

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Hydrodynamical simulations of type-II supernovae in one and two dimensions are performed for the revival phase of the delayed shock by neutrino energy deposition. Starting with a post-collapse model of the 1.31 Mʘ iron core of a 15 Mʘ star immediately after the stagnation of the prompt shock about 10 ms after core bounce, the models are followed for several hundred milliseconds with varied neutrino fluxes from the neutrino sphere. The variation of the neutrino luminosities is motivated by the considerable increase of the neutrino emission due to convective processes inside and close to the neutrino sphere (see Janka 1993), which are driven by negative gradients of entropy and electron concentration left behind by the prompt shock (Burrows & Fryxell 1992, Janka & Müller 1992). The size of this luminosity increase remains to be quantitatively analyzed yet and may require multi-dimensional neutrino transport. However, in the presented simulations the region below the neutrino sphere is cut out and replaced by an inner boundary condition, so that the convective zone is only partially included and the neutrino flows are treated as a freely changeable energy source.

For small neutrino luminosities the energy transfer to the matter is insufficient to revive the stalled shock. However, there is a sharp transition to successful explosions, when the neutrino luminosities lie above some ‘threshold value’. Once the shock is driven out and the density and temperature of the matter between neutrino sphere and shock start to decrease during the expansion, suitable conditions for further neutrino energy deposition are maintained, and an explosion results. With the neutrino energy deposition the entropy per nucleon in the region between neutrino sphere and shock grows, and convective overturn will set in. Multi-dimensional simulations show that due to the large pressure scale height a large-scale pattern of up-flows and down-flows with velocities close to the local speed of sound develops. Consequently, cold, postshock material is advected down into the neutrino heating layer close to the neutrino sphere and hot material is transported outwards, thus reducing energy losses by re-emission of neutrinos and increasing the pressure behind the shock. Therefore these convective processes are found to be a very important aid to the delayed supernova explosion. In fact, two-dimensional models explode even in cases where spherically symmetrical computations fail.

Type
Type lb and Type II Supernovae
Information
International Astronomical Union Colloquium , Volume 145: Supernovae and Supernova Remnants , 1996 , pp. 109 - 117
Copyright
Copyright © Cambridge University Press 1996

References

Bethe, H. A. 1990, Rev. Mod. Phys., 62, 801 Google Scholar
Bethe, H. A., Wilson, J.R. 1985, ApJ, 295, 14.Google Scholar
Bruenn, S. W. 1989a, ApJ, 340, 955 Google Scholar
Bruenn, S. W. 1989b, ApJ, 341, 385 Google Scholar
Bruenn, S. W. 1992, Numerical Simulations of Core Collapse Supernovae, in Proc. of 1st Symposium on Nuclear Physics in the Universe, Oak Ridge, Tennessee, Sept. 1992Google Scholar
Burrows, A. 1987, ApJ, 318, L57 Google Scholar
Burrows, A., & Lattimer, J. M. 1988, Phys. Rep., 163, 51 Google Scholar
Burrows, A., & Fryxell, B. A. 1992, Science, 258, 430 Google Scholar
Colella, Ph., & Woodward, P. R. 1984, J. Comp. Phys., 54, 174 Google Scholar
Fryxell, B. A., Müller, E., & Arnett, D. 1989, Hydrodynamics and Nuclear Burning, MPA-preprint, 449, Max-Planck-Institut für Astrophysik, Garching.Google Scholar
Herant, M., Benz, W., & Colgate, S. 1992, ApJ, 395, 642.Google Scholar
Janka, H.-Th. 1993, Neutrinos from Type-II Supernovae and the Neutrino-Driven Supernova Mechanism, in Frontier Objects in Astrophysics and Particle Physics, Conf. Proc. Vol. 40, Eds. Giovannelli, F. & Mannocchi, G., SIF, Bologna p. 345 Google Scholar
Janka, H.-Th., & Müller, E. 1992, Neutrino-Driven Type-II Supernovae Neutrino Heating and Post Bounce Dynamics, in Frontiers of Neutrino Astrophysics, Univ. Academy Press, Tokyo, Japan (in press); MPA-preprint, 711 Google Scholar
Janka, H.-Th., Zwerger, Th., & Mönchmeyer, R. 1993, A&A, 268, 360 Google Scholar
Lattimer, J. M., & Swesty, F. D. 1991, Nucl. Phys., A535, 331 Google Scholar
Mayle, R. W. 1985, Ph.D. Thesis, UC Berkeley, UCRL report no. 53713Google Scholar
Müller, E. 1993, Two- and Three-Dimensional Simulations of Convection in Protoneutron Stars, in Proc. of 7th Workshop on Nuclear Astrophysics, Ringberg Castle, Tegernsee, March 1993, MPA-report, in pressGoogle Scholar
Wilson, J. R., Mayle, R. W., Woosley, S. E., Weaver, T. 1986, Ann. N.Y. Acad. Sei., 470, 267 Google Scholar