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enter image description here Looking at the above photo, you will soon find it is impossible to explain what actually happens (with today's physics), in one word star is like a nuclear fusion bomb which its pressure is in balance against gravitational force.

  1. A supernova (or a black hole) is triggered by an imbalance between them, so isn't supernova a natural pure fusion bomb?

  2. Then what equations are able to simulate a virtual supernova explosion?

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    $\begingroup$ "you will soon find it is impossible to explain what actually happens" Actually you have to lean pretty hard on the word "exactly" for this sentence to resemble the truth; there is a reasonably detailed theory of supernovas in their several types and it can explain the main features, timing and intensity of the blasts. Moreover, the picture you exhibit doesn't give any evidence either way on the matter. $\endgroup$ – dmckee Jul 4 '13 at 1:28
  • $\begingroup$ No time for a full answer right now, but looking up 'supernova simulation code' gives a good number of hits. One I am a bit familiar with is FLASH (flash.uchicago.edu/site/research/Supernova.shtml) which does type Ia supernovae. Presumably if you dig around a bit in the papers and documentation you can find the relevant equations. $\endgroup$ – Kyle Oman Jul 4 '13 at 2:52
  • $\begingroup$ Part 2: Raychaudhuri Equation, Chandrashekhar Limit,... $\endgroup$ – Abhimanyu Pallavi Sudhir Jul 4 '13 at 15:26
  • $\begingroup$ Regarding my previous comment, I meant "answer to part 2 of the question". $\endgroup$ – Abhimanyu Pallavi Sudhir Jul 4 '13 at 18:30
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It's interesting you found Tycho as an example as this was one of the early recorded supernovas back in 1572...by Tycho of course. This is considered a Type Ia Supernova and the image you reference isn't really how it looks. That's a modified composite to visualize the microwave and infrared components of the remains together.

As Kyle mentioned, you can see a 3d simulated model of Tycho event where the core spills out and starts fusion computed by the FLASH Center for Computational Science. This simulation of high-energy density physics (HEDP) is not something you can just slap down an equation for. You can access their code if you can get permission. You also might enjoy the more artistic rendering of this event too.

You can also view an interesting presentation on this complex model by Daniel Kasen.

One of the key indicators of a white dwarf like this going super nova is determined by the Chandrasekhar Limit which is represented by the following formula: Formula

where:

  • $\hbar$ is the reduced Planck constant
  • c is the speed of light
  • G is the gravitational constant
  • $μ_e$ is the average molecular weight per electron, which depends upon the chemical composition of the star.
  • $m_H$ is the mass of the hydrogen atom.
  • $\omega_3^0$ $\approx$ 2.018236 is a constant connected with the solution to the Lane-Emden equation.

Once the mass becomes > $M_{limit}$ it becomes unstable.

And although the exact explosion mechanism for Type Ia supernovae is still unknown, and no progenitor system has ever been observed, astronomers agree that the data fits an explosion of a white dwarf that has exceeded its Chandrasekhar limit through interaction with a companion. The nature of this companion is still uncertain, but astronomers promote two basic models:

Models

In the double-degenerate model, the white dwarf merges with another carbon-oxygen white dwarf companion to exceed the Chandrasekhar limit. In this scenario there is no expectation to observe hydrogen in the spectra of Ia since both objects involved would have long ago used up their hydrogen.

In the single-degenerate model, the white dwarf accretes matter from a giant companion. In this case it is not unreasonable to expect hydrogen-rich material to exist around the white dwarf, and we should expect to see hydrogen in the spectra of Ia.

Until recently, no hydrogen had ever been detected in the spectra of Ia. This changed with the discovery of SN 2002ic. A Type Ia when first classified, its spectrum matched those of other Ia in all respects but one – there was a weak Hα line. This Type Ia spectrum evolved over a period of several weeks with the Hα emission becoming more and more dominant, to ultimately look exactly the same as a luminous Type IIn supernova. This discovery suggests that at least some Ia are the result of accretion from a giant star, and most astronomers agree that it pushes the already popular single-degenerate model well ahead of its competitor.

That Ia are the explosions of old white dwarf stars fits with the observation that Ia are discovered in all types of galaxies. In contrast, Type II, Type Ib and Type Ic supernovae result from the core-collapse of massive stars, and are only found in irregular galaxies or the arms of spiral galaxies where active star formation is taking place.

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  • $\begingroup$ Awesome answer, +1. Just one comment regarding the first sentence - do you not count SNe 1006 and 1054? $\endgroup$ – user10851 Jul 4 '13 at 5:15
  • $\begingroup$ @ChrisWhite thanks...yeah definitely not the first but perhaps the first best recorded SN. $\endgroup$ – user6972 Jul 4 '13 at 5:31

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