White Dwarf

White Dwarf

When stars reach the end of their long expanse, then the smaller stars - which are eight times larger than our own Sun - usually become white dwarves. These ancient stars are incredibly dense. One spoon will be heavier in the form of an elephant on earth - 5.5 tons. The white dwarf usually has only a radius of 0.01 times more than our own sun, but their mass is almost identical.

Our sun-like stars fuse hydrogen in helium. White dwarfs are stars that burn all of the hydrogens which they once use as nuclear fuels. Fusion in the core of a star produces heat and outside pressure, but this pressure is kept in balance by the incoming push of gravity generated by the mass of a star. When the hydrogen used in the form of fuel disappears, and if the fusion becomes slow, then the gravitational star itself collapses.

Formation of white dwarf

White dwarves are believed to represent the last point of stellar evolution for stars in the main sequence, which are about 0.07 to 10 M to the mass. The structure of the white dwarf produced will depend on the initial mass of the star. The current galactic model suggests that the Milky Way galaxy currently has about ten billion white dwarves.

Very low mass stars

If the mass of a main-sequence star is less than half the solar mass, then it will not be hot enough to fuse helium at its core. It is believed that, during a lifetime, which is more than the age of the universe (C. 13.8 billion years), a star will eventually burn all its hydrogen, will become a blue dwarf for a while, and A helium white will end your development. The dwarf is mainly composed of helium-4 nuclei. Due to taking a very long time in this process, it is not considered the origin of the helium white dwarf. Rather, they are considered to be a major loss product in binary systems or caused large scale loss due to large planet partners.

Low to medium-mass stars

If the mass of a main-sequence star like our Sun is between 0.5 and 8 M our, then its core through the triple-alpha process will be heated enough to fuse helium in carbon and oxygen, but the carbon It will never be hot enough to fuse. In neon. During the end of the period in which the fusion passes through responses, such stars will have a carbon-oxygen core which does not pass through the fusion reactions, which is surrounded by an internal helium-burning shell and an external hydrogen-burning shell.  On the Hertzsprung-Russell diagram, it will be found on the asymptomatic giant arm. By then it expels most of its external material until the only carbon-oxygen core is left, a planetary nebula is formed. This process is responsible for the carbon-oxygen white dwarfs, which produce the majority celebrated white dwarf.

Medium to High Mass Stars

If a star is sufficiently large, then its core will eventually heat enough to fuse from carbon to neon, and then to fuse the neon from the iron. Such a star will not become a white dwarf, because its central, non-fusing core mass, which is initially supported by the pressure of electron degeneration, will eventually be greater than the possible mass support by degeneration pressure. At this point, the core of the star will collapse and it will explode into a core-fall supernova that will leave behind a residual neutron star, black hole, or possibly more foreign form of a compact star. Some main-order stars, perhaps 8 to 10 M, are though, although adequately large enough for neon and magnesium from carbon, can be inadequately large for fusion neon. Such a star can leave a residual white dwarf primarily made of oxygen, neon, and magnesium, provided that its core does not fall, and provided that the fusion does not grow violently in order to blow the star in a supernova. Although some white dwarfs have been identified which can be of this type, most of the evidence for such existence comes from ONMG or Neon Nova called Nova. These Nova's spectra reflect the abundance of neon, magnesium and other intermediate-mass elements, which only shows the accumulation of material on the oxygen-neon-magnesium white dwarf.

Type Iax supernova

Type Iax supernovae, which involves helium accretion by a white dwarf, has been proposed to be a channel for the transformation of this type of stellar relic. In this scenario, a type of carbon explosion formed in type Ia supernovae is very weak to destroy the white dwarf, which exits a small part of its mass as ejecta, but produces an asymmetric explosion that causes Tara to Kills, which is often referred to as a zombie star, for the high speed of a hypervelocity star. In a failed explosion, the processed material is again re-joined with the heaviest elements by the white dwarf as it is deposited by falling into the roots of its roots. These iron-core white dwarves are smaller than the mass of carbon-oxygen and will be faster and crystallized than those people.

What's inside the white dwarf?

Because a white dwarf is not capable of making internal pressure (such as the release of energy from the fusion because the fusion has stopped), gravity compresses the matter to the inside, as long as the electrons that form the atoms of a white dwarf Is not broken together. In normal circumstances, equal electrons (similar "spin" ones) are not allowed to capture at the same level of energy. Since there are only two ways that an electron can spin, only two electrons can capture at a single energy level. This is known only as the Pauli exclusion principle in physics. In a normal gas, this is not a problem because there are not enough electron to completely fill all the energy levels. But in a white dwarf, density is very high, and all the electrons are very close together. It is known as a "degenerate" gas, which means that all the energy levels in its atoms are filled with electrons. To compress the white dwarf for gravity, it must force the electrons where they can not go. Once a star has degenerated, gravity can not make it more compressed, because quantum mechanics determines that there is no more available space to carry. That's why our white dwarf lives on, not by internal fusion, but by quantum mechanical principles that inhibit its complete collapse.

There are other unusual properties in the degenerate substance. For example, the smaller the white dwarf, the smaller it is, the smaller it is. The reason for this is that the larger the mass of a white dwarf, the more its electrons should squeeze together to maintain sufficient external pressure to support the extra mass. However, there may be a white dwarf that has a limit on the amount of mass. Subrahmanyan Chandrasekhar discovered this limit to be 1.4 times the mass of the Sun. It is properly known as "Chandrasekhar Border".

With the surface of 100,000 times the Earth's gravity, the atmosphere of a white dwarf is very strange. Heavy atoms in its atmosphere drown and remain on a light surface. Some white dwarfs have almost pure hydrogen or helium atmospheres, which are the lightest in the elements. Also, gravity pulls the atmosphere around it into a very thin layer. If it is on earth, then the top of the atmosphere will be below the top of the high-rise buildings.

Scientists hypothesize that under the atmosphere of many white dwarfs, there is a 50 km thick layer below. At the bottom of this crust is a crystalline lattice of carbon and oxygen atoms. Since a diamond is just crystallized carbon, therefore a cool carbon/oxygen can be compared between a white dwarf and a diamond.