24/07/2017
What is Supernova?
Supernova is a star explosion; it is very important for understanding our galaxy; it warms the interstellar medium, distributes heavy elements along the galaxy, and accelerates cosmic rays.
But what causes the explosion of the star? Is there more than one kind of supernova?
In fact, there seem to be two separate types of supernovae - those that occur for a single supermassive star and those that occur because the mass moves to a white dwarf in a binary system. As you will see, however, what distinguishes between the two types is the reason behind the explosion.
* Supernova resulting from a single supermassive star
The life of the stars, which have a mass of 8 times the mass of the sun or more, ends in an amazing way; they suffer from a supernova event.
The supernova explosion occurs when there is not enough fuel to make the nuclear fusion process at the heart of the star to create the necessary and outward pressure, which balances the inward gravity of the star resulting from the mass of the star.
First, the star will swell into a super-red giant ... at least at the outer limits.
Inside, the nucleus of the neutron star is gravitational and begins to contract; during shrinkage, it becomes hotter and denser. A new series of nuclear reactions begins to occur, temporarily stopping the breakdown of the heart.
Unfortunately, it is temporary!
When the heart mainly contains iron, it will have nothing else to do for nuclear fusion.
The process of nuclear fusion depends on the heart (because of the nuclear structure of the iron, iron fusion will not occur in the energy chain, and because energy production will not continue, the star will then collapse).
In less than a second, the star begins its final phase of the crash. The heart temperature rises to more than 100 billion degrees by melting iron atoms together.
The forces of gravity overcome the forces of repulsion between nuclei; the heart presses, but then rises; the energy of this upswing moves to the casing of the star, which then explodes and produces a shock wave.
The material is heated in the outer layers of the star while still facing the shock wave, and is fusion to form new elements and radioactive isotopes. The shock then drives the material away into space; the substance that explodes away from the star at this stage is known as the supernova.
All that remains of the original star is a super-dense, small heart, mostly composed entirely of neutron-star neutrons.
Or, if the original star is super-mass (to move 15 or more times the mass of the sun), then even neutron stars can not keep the heart ... and then a black hole is formed.
The hot materials produced by supernova - radioactive isotopes and free electrons that move within the neutron's magnetic field - produce X-rays and gamma rays; they are high-energy photons used by astronomers to study supernova and neutron stars.
* Brown dwarf undergoes thermal nuclear process
Another type of supernova is the sudden explosion of a white dwarf star in a binary star system.
The white dwarf is the ultimate end of the stars, which are about 8 times the mass of the sun; the remaining white dwarf has a mass of about 1.4 sun mass, roughly the size of the Earth.
In binary systems, the white dwarf is usually a red giant; the stars can be close enough to each other and the red giant is also large enough to carry the material towards the white dwarf.
The resulting matter from the accompanying star towards the white dwarf causes its mass to rise to 1.4 times the mass of the sun (this mass is called the Chandra Sigar boundary). When this happens, the pressure will increase in the center of the white dwarf and increase the threshold required by carbon and oxygen To break through the process of nuclear thermal integration.
When this threshold is exceeded, the thermal nuclear fusion of these elements begins uncontrollably at all; this leads to a nuclear explosion of heat for the whole star; nothing leaves it behind - except for some elements that remain from the white dwarf or that are formed within an explosion Supernova.
Among the new elements is radioactive nickel, which releases a huge amount of energy, including visible radiation; the evolution of these supernova species tends to be all similar.
NASA in Arabic
