scholarly journals Core Collapse, Bounce and Shock Propagation

1980 ◽  
Vol 58 ◽  
pp. 537-544
Author(s):  
Richard L. Bowers ◽  
James R. Wilson
Keyword(s):  
Inner Core ◽  
Shock Propagation ◽  
Iron Core ◽  
Core Collapse ◽  
Nuclear Density ◽  
Type Ii ◽  
Specific Entropy ◽  
Collapse Models ◽  
Recent Developments

Abstract.Recent developments in the physics input for iron core collapse models of type II supernovae are reviewed. The effect of these developments on collapse calculations is also discussed. The inner core collapses homologously, with little change in specific entropy, bounces in the neighborhood of nuclear density, and sets up; an outward moving shock. In adiabatic models an explosion may result. The inclusion of neutrino effects may produce substantial shock damping. Current results indicate that core collapse, bounce and shock propagation does not produce an explosion when neutrino effects are included.

scholarly journals The Effect of General Relativity and Equation of State on the Adiabatic Collapse and Explosion of a Stellar Core

1988 ◽  
Vol 108 ◽  
pp. 417-419
Author(s):  
N. Sack ◽  
I. Lichtenstadt
Keyword(s):  
General Relativity ◽  
Equation Of State ◽  
Inner Core ◽  
Massive Stars ◽  
Iron Core ◽  
Nuclear Density ◽  
Type Ii ◽  
Velocity Difference ◽  
Initial Strength ◽  
The Core

The collapse of the iron core of massive stars ( M ≥ 8 MO) is initiated by photodissociation and electron capture. The collapse of the inner core proceeds homologously until it is stopped by the stiffness of the equation of state (hereafter EOS) at nuclear density and it stops or rebounds. A shock forms at the edge of homology. The initial strength of the shock increases with the velocity difference between the inner and outer cores, i.e. it increases with a larger rebound of the inner core. The uniterrupted propagation of this prompt shock through the remainder of the core to the stellar mantle, where it can deliver enough energy to blow off the loosely bound outer layers, has long been proposed as the mechanism of type II supernovae explosions. However most authors did not get an explosion as a result of the prompt mechanism. Recently Baron et al. (1985) reported that the combination of General Relativity (GR) with a relatively soft EOS at nuclear densities leads to a much greater blow off than they got with Newtonian hydrodynamics. In order to see where purely hydrodynamical effects are important, namely for what EOS the GR outburst is greater than the Newtonian, we did a set of pure hydrodynamical adiabatic calculations (complete neutrino trapping) with different EOS above nuclear densities, turning the GR terms on and off. Neutrino leakage, which we do not incorporate, usually leads to harmful energy losses.

scholarly journals Blue supergiant progenitors from binary mergers for SN 1987A and other Type II-peculiar supernovae

2016 ◽  
Vol 12 (S329) ◽  
pp. 64-68
Author(s):  
Athira Menon ◽  
Alexander Heger
Keyword(s):  
Stellar Evolution ◽  
Evolutionary Model ◽  
Iron Core ◽  
Core Collapse ◽  
Type Ii ◽  
Sn 1987A ◽  
Ring Nebula ◽  
Binary Mergers ◽  
Evolution Study ◽  
Different Depths

AbstractWe present results of a systematic and detailed stellar evolution study of binary mergers for blue supergiant (BSG) progenitors of Type II supernovae, particularly for SN 1987A. We are able to reproduce nearly all observational aspects of the progenitor of SN 1987A, Sk –69 °202, such as its position in the HR diagram, the enrichment of helium and nitrogen in the triple-ring nebula and its lifetime before its explosion. We build our evolutionary model based on the merger model of Podsiadlowski et al. (1992), Podsiadlowski et al. (2007) and empirically explore an initial parameter consisting of primary masses, secondary masses and different depths up to which the secondary penetrates the He core during the merger. The evolution of the post-merger star is continued until just before iron-core collapse. Of the 84 pre-supernova models (16 M⊙ − 23 M⊙) computed, the majority of the pre-supernova models are compact, hot BSGs with effective temperature >12 kK and 30 R⊙ − 70 R⊙ of which six match nearly all the observational properties of Sk –69 °202.

scholarly journals Black Holes are a Mathematical Fantasy, not a Physical Reality

2019 ◽  
Vol 11 (4) ◽  
pp. 16
Author(s):  
Gurcharn S. Sandhu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Physical Reality ◽  
Iron Core ◽  
Core Collapse ◽  
Compressive Stresses ◽  
Collapse Models ◽  
Solid Iron ◽  
Physical Foundation

With recent detection of black hole mergers by LIGO, the 'Black Holes' and 'Neutron Stars' have become common house-hold names, albeit fanciful names in public domain. However, for the scientific community black holes are the ultimate paradoxes of nature. The claimed observations of black hole mergers are in fact interpretations of certain observations under the spacetime model of Relativity. These interpretations can change significantly with the change in operating model of the phenomenon. A black hole is believed to be a ‘region of spacetime’ exhibiting such strong gravitational effects that nothing, not even light can escape from it. We demonstrate in this paper that this conviction is based on erroneous derivation for the gravitational redshift and the correct derivation shows that a photon cannot be prevented from escaping a gravitating body of any mass and size. Due to erroneous depiction of spacetime as a physical entity in GR, a mathematical singularity predicted by Schwarzschild metric solution of EFE has been projected as a physical possibility in the form of Black Holes. To strengthen the physical basis of Black Hole creation, the observations of Super Nova explosions are being interpreted under core collapse models. The core collapse models are now regarded as the physical foundation of Black Holes and Neutron stars. In this paper we have established the invalidity of current core collapse models on the grounds of treating electrons, ions and nuclei as non-interacting particles and using kinetic theory of gases for analyzing compressive stresses in solid iron core.

scholarly journals Low-luminosity Type II supernovae – III. SN 2018hwm, a faint event with an unusually long plateau

2020 ◽  
Vol 501 (1) ◽  
pp. 1059-1071
Author(s):  
A Reguitti ◽  
M L Pumo ◽  
P A Mazzali ◽  
A Pastorello ◽  
G Pignata ◽  
...  
Keyword(s):  
Spectroscopic Data ◽  
Low Energy ◽  
Explosion Energy ◽  
Iron Core ◽  
Core Collapse ◽  
Type Ii ◽  
Balmer Lines ◽  
Hydrodynamical Simulations ◽  
Best Fit ◽  
Branch Star

ABSTRACT In this work, we present photometric and spectroscopic data of the low-luminosity (LL) Type IIP supernova (SN) 2018hwm. The object shows a faint (Mr = −15 mag) and very long (∼130 d) plateau, followed by a 2.7 mag drop in the r band to the radioactive tail. The first spectrum shows a blue continuum with narrow Balmer lines, while during the plateau the spectra show numerous metal lines, all with strong and narrow P-Cygni profiles. The expansion velocities are low, in the 1000–1400 km s−1 range. The nebular spectrum, dominated by H α in emission, reveals weak emission from [O i] and [Ca ii] doublets. The absolute light curve and spectra at different phases are similar to those of LL SNe IIP. We estimate that 0.002 M⊙ of 56Ni mass were ejected, through hydrodynamical simulations. The best fit of the model to the observed data is found for an extremely low explosion energy of 0.055 foe, a progenitor radius of 215 R⊙, and a final progenitor mass of 9–10 M⊙. Finally, we performed a modelling of the nebular spectrum, to establish the amount of oxygen and calcium ejected. We found a low M(16O)$\approx 0.02\, \mathrm{ M}_{\odot }$, but a high M(40Ca) of 0.3 M⊙. The inferred low explosion energy, the low ejected 56Ni mass, and the progenitor parameters, along with peculiar features observed in the nebular spectrum, are consistent with both an electron-capture SN explosion of a superasymptotic giant branch star and with a low-energy, Ni-poor iron core-collapse SN from a 10–12 M⊙ red supergiant.

scholarly journals The diverse lives of progenitors of hydrogen-rich core-collapse supernovae: the role of binary interaction

2019 ◽  
Vol 631 ◽  
pp. A5 ◽  
Author(s):  
Emmanouil Zapartas ◽  
Selma E. de Mink ◽  
Stephen Justham ◽  
Nathan Smith ◽  
Alex de Koter ◽  
...  
Keyword(s):  
Binary Stars ◽  
Binary Interaction ◽  
Core Collapse ◽  
Relative Importance ◽  
Type Ii ◽  
Population Synthesis ◽  
Binary Channel ◽  
History Of ◽  
Binary Channels

Hydrogen-rich supernovae, known as Type II (SNe II), are the most common class of explosions observed following the collapse of the core of massive stars. We used analytical estimates and population synthesis simulations to assess the fraction of SNe II progenitors that are expected to have exchanged mass with a companion prior to explosion. We estimate that 1/3 to 1/2 of SN II progenitors have a history of mass exchange with a binary companion before exploding. The dominant binary channels leading to SN II progenitors involve the merger of binary stars. Mergers are expected to produce a diversity of SN II progenitor characteristics, depending on the evolutionary timing and properties of the merger. Alternatively, SN II progenitors from interacting binaries may have accreted mass from their companion, and subsequently been ejected from the binary system after their companion exploded. We show that the overall fraction of SN II progenitors that are predicted to have experienced binary interaction is robust against the main physical uncertainties in our models. However, the relative importance of different binary evolutionary channels is affected by changing physical assumptions. We further discuss ways in which binarity might contribute to the observed diversity of SNe II by considering potential observational signatures arising from each binary channel. For supernovae which have a substantial H-rich envelope at explosion (i.e., excluding Type IIb SNe), a surviving non-compact companion would typically indicate that the supernova progenitor star was in a wide, non-interacting binary. We argue that a significant fraction of even Type II-P SNe are expected to have gained mass from a companion prior to explosion.

Recent developments in type-II superlattice detectors at IRnova AB

2012 ◽  
Author(s):  
Hedda Malm ◽  
Rickard Marcks von Würtemberg ◽  
Carl Asplund ◽  
Henk Martijn ◽  
Amir Karim ◽  
...  
Keyword(s):  
Type Ii ◽  
Type Ii Superlattice ◽  
Recent Developments
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