White Dwarfs Essay examples

On the other end of the spectrum, the death of a super-massive star is one of the most brilliant displays of pure power in the universe which includes an amazing light show which has no equal. A super-massive star is exactly what it sounds like, a star so big that it dwarfs our own star in every way. When a super-massive sun begins to run out of out of hydrogen it begins to collapse, but due to its immense gravity and size, the collapse produces such an abrupt implosion that the last remnants of nuclear fusion remaining push all the mass of the star back out into space (Britt, 2007). This can be compared to someone jumping onto a trampoline whose elastic has enough elasticity to force one back into the air. This occurrence is known as a supernova explosion, which is the largest explosion in the known universe. A supernova explosion can even be seen from other galaxies, as scientists have done witnessed from observations using the Hubble telescope. The star is so big, however, that it only blows its outer atmosphere away, still leaving a massive amount of matter that is doomed to collapse again, and this time it will be a one-way ticket to oblivion. The super-massive star finally collapses and its own incredible mass crushes it’s internally and now turns it into a neutron star. An average neutron star is about ten miles in diameter, or the size of Manhattan. Although this

     In the 18th century scientists started to research the after effects of a large star such as a supernova exploding. What happens of the gas and dust left behind after such a big star died? The idea of mass concentration so dense that even light would be trapped goes all the way back to Laplace in the 18th century. The first scientist to really take an in depth look at black holes and the collapsing of stars, was a professor, Robert Oppenheimer and his student Hartland Snyder, in the early nineteen hundreds. They came up with the basics of a black hole from Einstein’s theory of relativity that if the speed of light was the most speed over any massive object, then nothing could escape a black hole once in its grasp. These researchers showed that when a “sufficiently massive star” runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole. In general theory of relativity, gravity is a manifest of the curvature of the space-time.

One solar mass is equal to the mass of the Sun, about 2 nonillion kilograms. If a white dwarf were to exceed ~1.44 solar masses, its electron degeneracy pressure would not be able to support it.

Stars like our Sun, which are no more than 1.44 solar masses, will undergo fusion of hydrogen into helium. Over its life time the star slowly uses its supply of hydrogen by fusing it into helium. These reactions require high temperatures. Eventually the star will completely fuse hydrogen into helium in its core leaving inadequate amounts of thermal pressure to balance gravity. This will cause the centre of the star to contract to compensate for the heat energy lost.

Comparing red giants to the sun, they are about 1000 times larger. Compared to the sun’s temperature, a red giants temperature is about half as much. This is because the same amount of energy has to be spread out across a much more massive star causing it to be cooler than it was before. The name red giant was given to these stars because the change in temperature causes the star to shine in the redder part of the spectrum. Stars can spend anywhere between 1000 years and one billion years in the red giant phase. After a certain amount of time, the helium finally runs out and fusion stops. Since there is no more helium, gravity pushes the star inward. The stars outer atmosphere is then blown out into huge clouds of gas and dust which is known as planetary nebulae. These clouds of gas and dust are then made to make new stars. As for the core of the star, it is still there. The star is now a white dwarf. White dwarf stars occur when the red giant loses its outer atmosphere. White dwarf stars are extremely hot because they are composed of only the core of the star which is the hottest

The Low mass stars spend there main life as a fusion machine which turns hydrogen into helium and a very slow and methodical pace. When the energy released by this fusion reaches the surface it is released into space and this is the star luminosity. Over a long, long time sometimes billions of years a low mass star consumes the hydrogen in its core and converts it to helium, at which point the core starts to contract and shrink. Once all of the hydrogen inside the stars core begins to become totally exhausted, the core pressure gives way to the crush of gravity because it has no more fusion occurring in its core at that time. As the core shrinks rapidly and the outer layers start to expand the stars shape begins to grow in size and its luminosity becomes extraordinary brighter due to the outer shell starting to produce fusion more rapidly then the core did during the main sequence life of the star. As this situation grows more rapidly and extreme the core starts to rapidly burn again and fuse its core helium into carbon. Then just before its final death the star ejects its outer layers into space. This leaves only the degenerate carbon core and since this core is still very hot it emits intensely powerful ultraviolet radiation and glows brightly in what is known as a planetary nebula. The nebula fades and cools over around a million or so years and we are left with a white dwarf cooling indefinitely till

After low mass stars shed their colourful outer gas cloud their masses have greatly decreased. The compression continues, making the star more and more dense. However there is a limit to the density of these stars as a result of their relatively small mass. This limit is connected to the Pauli exclusion principle which says that identical electrons cannot exist in the same energy state as another electron. This energy state relates to the position and momentum of the electron. As the star takes up less space, there is less opportunity for electrons to exist in different energy states. The core now exists in a stable degenerative state, which halts any further compression and is now defined to be a white dwarf.

Exceptionally huge stars can experience center disruption when atomic combination abruptly gets to be distinctly not able to maintain the center against its own gravity which is the reason for a wide range of supernova aside from sort Ia. The fall may bring about brutal ejection of the external layers of the star bringing about a supernova, or the arrival of gravitational potential vitality might be lacking and the star may crumple into a dark opening or neutron star (fallen center of an expansive star) with little emanated vitality. Center collapse can be brought about by a few distinct systems: electron catch (capture) (a procedure in which the proton-rich core of an electrically unbiased molecule retains an inward nuclear electron); surpassing as far as possible the Chandrasekhar limit (the most extreme mass of a steady white small star (stellar leftover and is exceptionally thick, its mass is equivalent to that of the Sun, while its volume is tantamount to that of Earth, and so on. At the point when a gigantic star builds up an iron center bigger than the Chandrasekhar mass, it will never again have the capacity to bolster itself and will fall further to a neutron star or dark opening (dark

If it has a whitish appearance its temperature is somewhere in between like our Sun. We can see how this happens and how we can then divide stars by mass into three main groups (Red Giants, Main Sequence Stars and White Dwarfs [bluish]) on the Hertzsprung-Russell diagram. An HR Diagram is a graph that plots stars as points by measuring their stellar luminosity in typical solar units (x axis) and surface temperature in multiple luminosity of the Sun (y axis). The diagram provides information about stellar radii, because a star’s luminosity depends on both its surface temperature and its surface area or radius. As you can see on the graph stellar radii increase as we go from the high-temperature, low-luminosity corner (lower left)[White Dwarfs] to the low-temperature, high-luminosity corner (upper right) [Red Giants].

In most cases a star will move into the planetary nebula phase, as an expanding, glowing shell of hot gas also known as plasma. This happens from a low-mass star in the end of their red giant phase, becoming unstable. The exterior layer drifts away from it’s core, which is now consider a white dwarf star, due to stellar winds. If the dying star have a mass of over 8 suns, it will become a supernova. Just like a planetary nebula, the cause of it is when a star runs out of nuclear fuel. From the massive star’s lack of outward pressure to balance its inward gravity, the star collapses into the core expelling a nuclear explosion. Also like the nebula, gas and dusts are scattered around space that will be used for the birth of future stars. At this point, the former supergiant is either a neutron star or a black

Neutron stars have larger masses than white dwarfs, but not only have they shrunk to a size smaller than the earth, they have shrunk to a fraction of the size of the earth, typically only 10km in diameter. As such, this type of death star is much denser. The mass of this new ‘dead’ star is great enough to overcome the electron degeneracy force, which stopped the collapse of the white dwarf but is eventually halted by yet another degeneracy force, neutron degeneracy (Read, 2017). During the collapse protons are forced to combine with electrons to produce neutrons until all that is left is neutrons. Similar to what happens in white dwarfs, as gravity pushes down on the star, it reaches a point where neutrons can’t be forced any closer so again the collapse stops. The mass squished into a ball 10 km in radius, can be upwards of 1.4Msun to up to 3M, thus clearly the density of a neutron star is much greater than a white dwarf. The escape velocity of such a body is about half the speed of light, which results in an incredibly strong gravitational force at the surface. This ultimately affects light leaving the

This would mean that the theory that dwarfs form similarly to stars despite being smaller and such holds true. If dwarfs had not emitted jets or done anything like this, it would mean that the dwarfs have a similar formation to that of planets.

In the article, the author explains how astronomers have discovered a star system that have possibly left behind a white dwarf after a weak supernova explosion. For instance, Type Ia are mini supernovas and are important because they are used to measure the distance and the expansion of the universe. Therefore, the Type Ia demonstrates supernova, they noticed they were viewing the light of the star that lost its outer hydrogen cover, which caused it to reveal its helium core. In addition, astronomers predicted that the Type lax supernovea were developed by a white dwarf and a helium binary star system. Astronomers explained a possible reason for SN 2012Z became a weak supernova, since it is one of the most powerful Type lax supernovae. For

A white dwarf is what starts like the sun become after they have exhausted their nuclear fuel. A white dwarf can also be called a degenerate dwarf. White dwarf stars are very dense, its mass is compared to the sun while it’s volume is compared to the Earth. White dwarfs are one of the densest objects of matter.

Main sequence stars like our own sun enduring in a state of nuclear fusion during which they will produce energy for billions of years by replacing hydrogen to helium. Stars change over billions of years. When their main sequence phase ends they pass through other states of existence according to their size and other characteristics. The larger a star's mass, the shorter its lifespan is. As stars move toward the end of their lives, much of their hydrogen will be converted to helium. Helium sinks to the star's core and raises the star's temperature—causing its outer shell to expand. These large, puffy stars are known as Red Giants. The red giant phase is actually a prelude to a star shedding its outer layers and becoming a small, dense body called a White Dwarf. White dwarfs cool down for billions and billions of years, until they finally go dark and produce no energy at all. Once this happens, scientists have yet to observe, such stars become known as Black Dwarfs. A few stars avoid this evolutionary path and instead go out with a bang, exploding as Supernovae. These violent explosions leave behind a small core that will then turn into something called a Neutron Star or even, if the remainder is large enough, it is then turned into something called a Black Hole.