scholarly journals Plasma screening of nuclear fusion reactions in liquid layers of compact degenerate stars: a first-principle study

2021 ◽  
Vol 508 (2) ◽  
pp. 2134-2141
Author(s):  
D A Baiko
Keyword(s):  
Neutron Stars ◽  
Nuclear Fusion ◽  
Pair Correlation ◽  
Reaction Rates ◽  
Fusion Reactions ◽  
Plasma Screening ◽  
Wide Range ◽  
Type Ia ◽  
Nuclear Fusion Reactions ◽  
Ia Supernovae

ABSTRACT A reliable description of nuclear fusion reactions in inner layers of white dwarfs and envelopes of neutron stars is important for realistic modelling of a wide range of observable astrophysical phenomena from accreting neutron stars to Type Ia supernovae. We study the problem of screening of the Coulomb barrier impeding the reactions by a plasma surrounding the fusing nuclei. Numerical calculations of the screening factor are performed from the first principles with the aid of quantum-mechanical path integrals in the model of a one-component plasma of atomic nuclei for temperatures and densities typical for dense liquid layers of compact degenerate stars. We do not rely on various quasi-classic approximations widely used in the literature, such as factoring out the tunnelling process, tunnelling in an average spherically symmetric mean-force potential, usage of classic free energies and pair correlation functions, linear mixing rule, and so on. In general, a good agreement with earlier results from the thermonuclear limit to Γ ∼ 100 is found. For a very strongly coupled liquid 100 ≲ Γ ≤ 175, a deviation from currently used parametrizations of the reaction rates is discovered and approximated by a simple analytic expression. The developed method of nuclear reaction rate calculations with account of plasma screening can be extended to ion mixtures and crystallized phases of stellar matter.

scholarly journals 16O(p,α)13N makes explosive oxygen burning sensitive to the metallicity of the progenitors of type Ia supernovae

2019 ◽  
Vol 627 ◽  
pp. A146
Author(s):  
E. Bravo
Keyword(s):  
Supernova Remnants ◽  
Fusion Reaction ◽  
Reaction Rates ◽  
Type Ia Supernovae ◽  
Fusion Reactions ◽  
Maximum Brightness ◽  
Theoretical Predictions ◽  
Type Ia ◽  
Standard Values ◽  
Ia Supernovae

Even though the main nucleosynthetic products of type Ia supernovae belong to the iron-group, intermediate-mass alpha-nuclei (silicon, sulfur, argon, and calcium) stand out in their spectra up to several weeks past maximum brightness. Recent measurements of the abundances of calcium, argon, and sulfur in type Ia supernova remnants have been interpreted in terms of metallicity-dependent oxygen burning, in accordance with previous theoretical predictions. It is known that α-rich oxygen burning results from 16O→12C followed by efficient 12C+12C fusion reaction, as compared to oxygen consumption by 16O fusion reactions, but the precise mechanism of dependence on the progenitor metallicity has remained unidentified so far. I show that the chain 16O(p,α)13N(γ,p)12C boosts α-rich oxygen burning when the proton abundance is large, increasing the synthesis of argon and calcium with respect to sulfur and silicon. For high-metallicity progenitors, the presence of free neutrons leads to a drop in the proton abundance and the above chain is not efficient. Although the rate of 16O(p,α)13N can be found in astrophysical reaction rate libraries, its uncertainty is unconstrained. Assuming that all reaction rates other than 16O(p,α)13N retain their standard values, an increase by a factor of approximately seven of the 16O(p,α)13N rate at temperatures in the order 3−5 × 109 K is enough to explain the whole range of calcium-to-sulfur mass ratios measured in Milky Way and LMC supernova remnants. These same measurements provide a lower limit to the 16O(p,α)13N rate in the mentioned temperature range, on the order of a factor of 0.5 with respect to the rate reported in widely used literature tabulations.

scholarly journals Significantly super-Chandrasekhar mass-limit of white dwarfs in noncommutative geometry

2021 ◽  
Vol 30 (05) ◽  
pp. 2150034
Author(s):  
Surajit Kalita ◽  
Banibrata Mukhopadhyay ◽  
T. R. Govindarajan
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Compact Object ◽  
Type Ia Supernovae ◽  
Mass Limit ◽  
Fusion Reactions ◽  
Standard Candle ◽  
Type Ia ◽  
Nuclear Fusion Reactions ◽  
Ia Supernovae

Chandrasekhar made the startling discovery about nine decades back that the mass of compact object white dwarf has a limiting value once nuclear fusion reactions stop therein. This is the Chandrasekhar mass-limit, which is [Formula: see text] for a nonrotating non-magnetized white dwarf. On approaching this limiting mass, a white dwarf is believed to spark off with an explosion called type Ia supernova, which is considered to be a standard candle. However, observations of several over-luminous, peculiar type Ia supernovae indicate the Chandrasekhar mass-limit to be significantly larger. By considering noncommutativity among the components of position and momentum variables, hence uncertainty in their measurements, at the quantum scales, we show that the mass of white dwarfs could be significantly super-Chandrasekhar and thereby arrive at a new mass-limit [Formula: see text], explaining a possible origin of over-luminous peculiar type Ia supernovae. The idea of noncommutativity, apart from the Heisenberg’s uncertainty principle, is there for quite sometime, without any observational proof however. Our finding offers a plausible astrophysical evidence of noncommutativity, arguing for a possible second standard candle, which has many far-reaching implications.

Status of muon catalysis of nuclear fusion reactions

1990 ◽  
Vol 160 (8) ◽  
pp. 47-103 ◽  
Author(s):  
Leonid I. Men'shikov ◽  
L.N. Somov
Keyword(s):  
Nuclear Fusion ◽  
Fusion Reactions ◽  
Nuclear Fusion Reactions ◽  
Muon Catalysis

Proposed Solutions to Achieve Nuclear Fusion

Engevista ◽  
2017 ◽  
Vol 19 (5) ◽  
pp. 1496
Author(s):  
Relly Victoria Virgil Petrescu ◽  
Raffaella Aversa ◽  
Antonio Apicella ◽  
Florian Ion Petrescu
Keyword(s):  
Nuclear Reactor ◽  
Nuclear Reactions ◽  
Nuclear Fusion ◽  
Nuclear Fission ◽  
Light Nuclei ◽  
Fast Neutrons ◽  
Fusion Reactions ◽  
Nuclear Fusion Reactions ◽  
The Masses ◽  
Fusion Products

Despite research carried out around the world since the 1950s, no industrial application of fusion to energy production has yet succeeded, apart from nuclear weapons with the H-bomb, since this application does not aims at containing and controlling the reaction produced. There are, however, some other less mediated uses, such as neutron generators. The fusion of light nuclei releases enormous amounts of energy from the attraction between the nucleons due to the strong interaction (nuclear binding energy). Fusion it is with nuclear fission one of the two main types of nuclear reactions applied. The mass of the new atom obtained by the fusion is less than the sum of the masses of the two light atoms. In the process of fusion, part of the mass is transformed into energy in its simplest form: heat. This loss is explained by the Einstein known formula E=mc2. Unlike nuclear fission, the fusion products themselves (mainly helium 4) are not radioactive, but when the reaction is used to emit fast neutrons, they can transform the nuclei that capture them into isotopes that some of them can be radioactive. In order to be able to start and to be maintained with the success the nuclear fusion reactions, it is first necessary to know all this reactions very well. This means that it is necessary to know both the main reactions that may take place in a nuclear reactor and their sense and effects. The main aim is to choose and coupling the most convenient reactions, forcing by technical means for their production in the reactor. Taking into account that there are a multitude of possible variants, it is necessary to consider in advance the solutions that we consider them optimal. The paper takes into account both variants of nuclear fusion, and cold and hot. For each variant will be mentioned the minimum necessary specifications.

scholarly journals Type Ia supernovae and remnant neutron stars

2001 ◽  
Vol 320 (3) ◽  
pp. L45-L48 ◽  
Author(s):  
A. R. King ◽  
J. E. Pringle ◽  
D. T. Wickramasinghe
Keyword(s):  
Neutron Stars ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae

scholarly journals Are the Precursors of Type Ia Supernovae Double Degenerate Mergers?

2004 ◽  
Vol 194 ◽  
pp. 111-112
Author(s):  
Lilia Ferrario
Keyword(s):  
Neutron Stars ◽  
White Dwarf ◽  
White Dwarfs ◽  
Observational Evidence ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae

AbstractI argue that the observational evidence for white dwarf-white dwarf mergers supports the view that they give rise to ultra-massive white dwarfs or neutron stars through accretion induced collapse. The implications for the progenitors of Type Ia SNe are discussed.

scholarly journals Continuous gravitational wave from magnetized white dwarfs and neutron stars: possible missions for LISA, DECIGO, BBO, ET detectors

2019 ◽  
Vol 490 (2) ◽  
pp. 2692-2705 ◽  
Author(s):  
Surajit Kalita ◽  
Banibrata Mukhopadhyay
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
White Dwarfs ◽  
Direct Detection ◽  
Angular Frequency ◽  
Compact Objects ◽  
Rotation Axes ◽  
Type Ia ◽  
Ia Supernovae

ABSTRACT Recent detection of gravitational wave from nine black hole merger events and one neutron star merger event by LIGO and VIRGO shed a new light in the field of astrophysics. On the other hand, in the past decade, a few super-Chandrasekhar white dwarf candidates have been inferred through the peak luminosity of the light curves of a few peculiar Type Ia supernovae, though there is no direct detection of these objects so far. Similarly, a number of neutron stars with mass $>\! 2\, \mathrm{M}_\odot$ have also been observed. Continuous gravitational wave can be one of the alternate ways to detect these compact objects directly. It was already argued that magnetic field is one of the prominent physics to form super-Chandrasekhar white dwarfs and massive neutron stars. If such compact objects are rotating with certain angular frequency, then they can efficiently emit gravitational radiation, provided their magnetic field and rotation axes are not aligned, and these gravitational waves can be detected by some of the upcoming detectors, e.g. LISA, BBO, DECIGO, Einstein Telescope, etc. This will certainly be a direct detection of rotating magnetized white dwarfs as well as massive neutron stars.

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