Parametric transition from deflagration to detonation in stellar medium
Peter V Gordon1, Leonid Kagan2, Gregory Sivashinsky2
1Department of Mathematical Sciences, Kent State University, Kent, Ohio 44242, USA.
Physical Review. E
|April 17, 2021
Summary
This study investigates thermonuclear explosions in white-dwarf stars, revealing a pressure runaway mechanism in stellar flames. This finding challenges existing theories on flame transitions in stellar explosions.
Area of Science:
- Astrophysics
- Stellar Evolution
- Thermonuclear Reactions
Background:
- The precise mechanism behind thermonuclear explosions in white-dwarf stars remains a fundamental astrophysical problem.
- A prevailing theory suggests these explosions result from a deflagration-to-detonation transition in an outward-propagating thermonuclear flame.
- Instability-induced corrugations are believed to play a crucial role in this transition process.
Purpose of the Study:
- To apply findings from terrestrial flame research, specifically a positive feedback mechanism leading to pressure runaway, to the astrophysical context of white-dwarf stars.
- To investigate the persistence of the runaway effect in stellar environments despite modifications to the equation of state.
- To challenge the conventional view that a flame must cross the Chapman-Jouguet deflagration threshold for transition.
Main Methods:
- Application of a terrestrial flame positive feedback mechanism to stellar environments.
- Analysis of thermonuclear flame propagation under modified equations of state.
- Investigation of flame behavior approaching the runaway point, specifically its subsonic nature.
Main Results:
- The pressure runaway effect, identified in terrestrial flames, persists in the stellar environment even with significant equation of state modifications.
- The study demonstrates that a thermonuclear flame can remain subsonic as it approaches the runaway point.
- This finding contradicts the established view that a flame must exceed the Chapman-Jouguet deflagration threshold to transition.
Conclusions:
- The identified pressure runaway mechanism offers a new perspective on the initiation of thermonuclear explosions in white-dwarf stars.
- The ability of a subsonic flame to approach runaway conditions necessitates a re-evaluation of the deflagration-to-detonation transition theory in astrophysics.
- This research provides a first-principle interpretation that could resolve long-standing questions about stellar explosion dynamics.
Related Concept Videos
01:02Flame Photometry: Overview
1.0K
Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a sample using a flame as the source of excitation energy. The concept of flame photometry was realized in the early 1860s by Kirchhoff and Bunsen, who discovered that specific elements emit characteristic radiation when excited in flames. The first instrument developed for this purpose was used to measure sodium (Na) in plant ash using a Bunsen...
1.0K
02:39Phase Transitions: Vaporization and Condensation
19.6K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules...
19.6K
02:14Combustion Energy: A Measure of Stability in Alkanes and Cycloalkanes
7.4K
The low reactivity in alkanes can be attributed to the non-polar nature of C–C and C–H σ bonds. Alkanes, therefore, were initially termed as “paraffins,” derived from the Latin words: parum, meaning “too little,” and affinis, meaning “affinity.”
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified...
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified...
7.4K
01:12Rocket Propulsion In Empty Space - II
3.1K
The motion of a rocket is governed by the conservation of momentum principle. A rocket's momentum changes by the same amount (with the opposite sign) as the ejected gases. As time goes by, the rocket's mass (which includes the mass of the remaining fuel) continuously decreases, and its velocity increases. Therefore, the principle of conservation of momentum is used to explain the dynamics of a rocket's motion. The ideal rocket equation gives the change in velocity that a rocket...
3.1K
01:03Rocket Propulsion in Gravitational Field - II
2.5K
A rocket's velocity in the presence of a gravitational field is decreased by the amount of force exerted by Earth's gravitational field, which opposes the motion of the rocket. If we consider thrust, that is, the force exerted on a rocket by the exhaust gases, then a rocket's thrust is greater in outer space than in the atmosphere or on a launch pad. In fact, gases are easier to expel in a vacuum.
A rocket's acceleration depends on three major factors, consistent with the...
A rocket's acceleration depends on three major factors, consistent with the...
2.5K
01:16Flame Photometry: Lab
572
In a flame photometer, when a solution like potassium chloride is aspirated into the flame, the solvent evaporates, leaving behind dehydrated salt. This salt dissociates into free gaseous atoms in their ground state. Some of these atoms absorb energy from the flame, leading to their excitation. The excited atoms return to the ground state, emitting photons at characteristic wavelengths. Because only electronic transitions are involved, the resulting emission lines are very narrow. The intensity...
572