Novas

Depends on the age of the neutron star. As a neutron star no longer has any method to produce heat, it will slowly cool over time.

A young neutron star will have a core temperature of about 106 kelvin.

Stars are giant nuclear fusion reactors; with their intense heat and pressure from their immense gravity, they smash hydrogen atoms into helium -- this is called fusion. Helium atoms fuse together to become heavier elements; this is how all of the elements past hydrogen and helium were created (hydrogen was created by the creation of the universe, and it is believed some helium may have been created then, too, but every element past helium owes its existence to the nuclear fusion in stars). This fusion process generates energy for the star (some of the particles making up the atoms that are smashed together are converted into energy during the fusion process), which is why stars continue to burn for so long -- the fusion of atoms generates energy that fuses more atoms together.

As atoms get heavier, however, they are more resistant to fusion and it takes more energy to smash the atoms together. Past iron, atoms require more energy to fuse together than the energy that comes out of the fusion process. The fusion process continues, however, because not all of a star fuses to the same element at the same time (100% of the hydrogen doesn't fuse immediately into helium ... by the time iron atoms are created, there is still plenty of hydrogen still fusing). Because stars are fluid-like plasma, heavier atoms readily sink through to the star's core. It is not a steady process, however ... heavier atoms can sometimes trap lighter ones beneath them. Gradually, though, more and more iron concentrates in the core ... but while fusion is still going on from lighter elements, the iron atoms continue fusing to heavier elements.

Eventually, however, there are too many heavy atoms in a star's core and the fusion fire seizes. The iron atoms collapse and a huge explosion is generated -- depending on the star's size, this can be a nova or supernova (plural novae or supernovae). The energy of this explosion blasts away the dead star's material, including the iron and heavier elements. The heavier elements will tend to form dust and other debris, that may eventually join with clouds of hydrogen to form part of a new solar system.

This is how the elements present in our solar system, and right here on Earth, came to be -- from carbon which makes up most life down to the ultra-heavy atoms like uranium, all of it was created in the fusion of stars and blasted away by novae and supernovae.

Before a white dwarf, a star would undergo the red giant phase. After a white dwarf, a star may end its life cycle as a black dwarf, although no black dwarfs are currently known to exist in the universe due to the long timescales required for a white dwarf to cool down.

Yes, white dwarfs are extremely hot when they first form but over billions of years they gradually cool and dim as they release their leftover thermal energy into space. This cooling process is what eventually transforms them into cold, dark celestial objects known as black dwarfs.

As a white dwarf loses energy and cools down, it eventually transitions into a black dwarf. A black dwarf is a hypothetical stellar remnant that has cooled to the point where it no longer emits heat or light. It is smaller and denser than a white dwarf.

Red dwarfs have not yet evolved into white dwarfs because red dwarfs are much less massive than other types of stars that do become white dwarfs. Red dwarfs are the smallest and coolest stars, and they have not burned through their fuel quickly enough to go through the stage of becoming a white dwarf. It will take billions of years for a red dwarf to cool and fade into a white dwarf.

A small star that only gives off faint light and is relatively cool is likely a red dwarf star. These stars are much smaller and cooler than our Sun, but they are the most common type of star in the universe. Despite their dim appearance, red dwarfs can be very long-lived.

Currently, we do not have the technology to directly harvest energy from supernovae. Supernovae release an immense amount of energy in a short period of time, but they are so far away and the energy is dispersed over a large area, making it impractical to capture. Additionally, the energy released in a supernova is on a scale far beyond our current capabilities to harness.

They are essentially the same thing, a White dwarf is thought to become a black dwarf once the temperature has cooled. There are not thought to be any black dwarfs in the universe as it's currently too young.

Because the stellar remnant has no more fuel to burn and any residual heat left over from when it was a white dwarf has left.

In fact it should just be called a cold rock.

See related question.

No, a white dwarf is a small, dense star that has exhausted its supply of nuclear fuel and is no longer able to sustain nuclear fusion reactions in its core. White dwarfs are the remnants of stars that were once similar to the Sun, and they are typically about the size of Earth but much more massive. They are called "white" dwarfs because they are extremely hot and glow with a white-hot light, but they are not capable of fusing elements because they do not have the necessary conditions (temperature, density, and pressure) to sustain nuclear fusion in their cores.

A supernova. It is an explosion that crushes the core of the star into a black hole or neutron star, and blasts all of the remaining mass of the star out into space.

We know that our Sun is a 3rd generation star, because the Earth contains elements like iron, gold, lead, or uranium that can ONLY be produced in a supernova.

And us? We're star-stuff; the iron atoms in our blood and the calcium atoms in our bones has already been through at least ONE supernova explosion.

By accretion of hydrogen from a nearby star which ignites and starts nuclear fusion in a runaway manner. The explosion is only on the surface of the white dwarf - this is a nova [See related question]

If however, it accretes enough hydrogen to push it's mass over the Chandrasekhar limit [See related link] of about 1.38 solar masses, the whole white dwarf will explode as a supernova type Ia [See related link]

Elements like carbon, oxygen, and nitrogen were likely generated during a Crab Nebula explosion. These explosions, known as supernovae, are powerful enough to create heavier elements through nuclear fusion processes.

Yes it can. In fact RS Ophiuchi (about 5,000 light years away) has erupted in 1898, 1933, 1958, 1967, 1985, and 2006. It is in it's "quiet" phase at the moment, but will more than likely erupt again in the future (around 2026)

The Earth is said to be undergoing differentiation when heavier elements sink towards the core and lighter elements rise to the top. This process results in the formation of distinct layers within the Earth based on differences in density.

Fusion reactions in red supergiants and supernovae create elements heavier than iron, such as gold, silver, and uranium. These elements form during the explosive deaths of massive stars, scattering their enriched stellar material into the cosmos. This process is essential for the formation of planets, life, and the diversity of elements in the universe.

If the core of a supernova explosion contains three or more solar masses of matter, it will most likely become a black hole. The gravitational force is so strong that the core collapses into a singularity, forming a black hole.

A white dwarf is typically about 100 times smaller in diameter compared to a main sequence star of similar mass. This is because white dwarfs are very dense, with mass comparable to a star but packed into a much smaller volume.

When fusion stops in a star it will start to fuse helium and will become a red giant.

A Nebula is A Cloud in space of Steller Dust And Gas In Which dust and gas particles collapse inwards to form new stars and the remaining debris could form new planets. Picture It Like a bag of soil. The Nebula Cloud is the soil and new stars are growing from it. Sometimes when large masses of matter collapse inwards new galaxies are formed.

Supernova is formed during death of a star ,during which enormous amount of energy is given out.

Whereas a black hole can be thought to be an object having large mass and very small radius , so that it's escape velocity is greater than that of light ,that is even light cannot escape from it's gravitational attraction force.

A hypernova is a more powerful and larger explosion than a supernova. It occurs when a massive star collapses and releases an immense amount of energy, much greater than that of a supernova. Hypernovae are one of the most energetic events in the universe.

It takes that long for the light depicting the event, to get here. If a star is 1,000 light-years away, that means it will take 1,000 years for the light depicting the event to get here. In other words, we see it as it was 1,000 years ago.

Light dosent travel to us that quickly and it's so far away that the light takes so many years or so to arrive here for us to see.

A supernova is a star that explodes. Stars about the size of our Sun explode when they run out of "fuel". The fuel they have is Hydrogen which they fuse into Helium and thus convert mass into energy (they shine brightly), Then the Helium and some Hydrogen are fused into heavier elements (Lithium etc) making more energy. All elements heavier than Carbon and lighter than Iron are made in the supernova explosion that comes at the end of the star's "life". Heavier stars will make even heavier elements.

The Earth is mostly made of these heavier elements. We are all stardust.