Novas

The leftover material from a supernova explosion forms either a neutron star or a black hole, depending on the mass of the collapsing core. A neutron star is extremely dense and composed mostly of neutrons, while a black hole is a region of spacetime where gravity is so strong that not even light can escape.

Pulsars were discovered in the Crab Nebula, a supernova remnant, in 1967. The Crab Pulsar is a neutron star at the center of the nebula that emits beams of radiation, producing regular pulses of light. The high-energy particles and magnetic fields in the nebula power the pulsar's emission.

The core of a supernova can create dense neutron stars or black holes, while the outer layers can be expelled into space to form new stars, planets, and other celestial bodies. Additionally, elements with atomic numbers higher than iron are formed in a supernova's intense heat and pressure through nucleosynthesis.

A white dwarf is the remains of an old star, but they still remain very hot and will continue to shine as a white dwarf for many millions of years until they gradually cool off to become black dwarfs. They are very dense.

Of course not. Even if our Sun was going to go supernova, which it won't. There would still be a delay of 8.333 minutes for the light to reach us.

Obviously - if you were right next to it, you could eliminate the delay, but you would be unable to observe it, as you would become part of the supernova instantly.

A supernova is a powerful and explosive event that occurs when a star reaches the end of its life cycle and collapses in on itself. The explosion releases an immense amount of energy, leading to the formation of new elements and the dispersal of these elements into space. Supernovae can also result in the formation of neutron stars or black holes.

Hotter and dimmer.

It's much smaller, but much denser.

The magnitude of Cassiopeia A, a supernova remnant, varies depending on the wavelength observed. In visible light, its magnitude is around 12.2, making it too faint to be seen with the naked eye. At radio wavelengths, it is much brighter due to synchrotron radiation emitted by high-energy electrons.

No, iron is not the heaviest element made in massive stars. Massive stars produce elements through nuclear fusion in their cores, creating heavier elements than iron, such as lead, gold, and uranium. Iron is often referred to as the endpoint of nuclear fusion in massive stars because the energy required to fuse iron exceeds the energy output of the reaction.

Because luminosity is a measure of brightness over distance. Also white dwarfs are a hundred times smaller than the Sun.

Most white dwarfs are a long way away and thus are difficult to see.

Population III stars more than likely created the first black holes, which became the supermassive black holes at the centres of most galaxies.

They also produced the first "metals" into the new Universe.

White dwarfs become novae when they accrete matter from a companion star's outer layers. This matter builds up on the surface of the white dwarf until a critical temperature and pressure is reached, triggering a runaway nuclear fusion reaction. This explosion releases a vast amount of energy and causes the white dwarf to temporarily brighten significantly.

When a white dwarf exceeds the Chandrasekhar limit of about 1.4 times the mass of the Sun, electron degeneracy pressure is no longer able to support the star against gravity. This leads to the collapse of the white dwarf, resulting in a supernova explosion.

The end of fusion. With nothing left to convert, the star's remains collapse inward on themselves. The tremendous heat and pressure caused by this rapidly creates all natural elements heavier than iron, and releases the most immense amount of energy in heat and light known in the universe. Much of the elements created are blown off into interstellar space, and the collapsed remains become a neutron star, the densest object in the universe, unless it was an exceptionally large star to begin with, then the remains become a Black Hole.

Electron degeneracy pressure, a quantum mechanical effect, supports the white dwarf against gravitational collapse. According to the Pauli exclusion principle, no two electrons can occupy the same quantum state, leading to pressure that counteracts gravitational forces. This pressure prevents further collapse and maintains the equilibrium of a white dwarf.

It will explode. As Betelgeuse is only about 650 light years away, it is more than likely that it will be visible during the day and outshine the Moon at night.

Contrary to "Internet" belief it will not destroy the Earth with it's gamma ray burst, as it's rotational axis is not pointed towards us.

It may be seen anytime soon, astronomically speaking.

No, Luna is not a constellation. Luna refers to the Earth's moon. Constellations are groups of stars that form recognizable patterns in the sky.

Massive stars, typically around eight times the mass of our sun, will end their life in a supernova explosion. During the explosion, the outer layers of the star are expelled into space, leaving behind a dense core known as a neutron star or black hole.

When a star explodes it creates a supernova. New NASA observations show the residue of what they believe to be "star guts" and the Hubble Space telescope allows scientists to measure the velocity and composition of the supernova caused by the exploding star.

By the time a star reaches the white dwarf stage, it's already about as compact as it's possible for ordinary matter to get... the size is maintained by electron degeneracy pressure, which is a fancy way of saying "the atoms are already touching, contracting any more would mean forcing the electrons into the nucleus."

When stars explode, they release a tremendous amount of energy in the form of light, heat, and various particles. Depending on the type of explosion, the star could become a supernova, leaving behind a dense core known as a neutron star or black hole, or it could completely destroy the star in a violent burst. The explosion also disperses heavy elements and dust into space, which can then contribute to the formation of new stars and planets.

• A nova is when a white dwarf or neutron star in a binary system collects enough hydrogen from its partner star, into an atmosphere around itself that is compressed enough to initiate fusion.
• A supernova is when a star dies and collapses into a neutron star or black hole, the collapse is fast enough that to conserve momentum the outer layers of the star are violently blown off in an explosion powerful enough to have the excess energy to produce all the elements past iron well into the transuranics. Supernovas only occur in stars that are very large and very hot to begin with.

• A nova occurs when a white dwarf or neutron star in a binary star system collects enough hydrogen from its partner star's wind and/or flares to trigger fusion. The entire collected hydrogen atmosphere around the star suddenly undergoes fusion and converting to helium very much like in an enormous yield fusion bomb. This will repeat over and over again, as long as the partner star can supply hydrogen.
• A supernova occurs when a high mass star dies and becomes a neutron star. As the core collapses because fusion burns out and radiation pressure can no longer hold it up, then degenerate electron pressure can not hold it up, the electrons are forced into the nucleus and combine with protons to form neutrons, the strong force causes the nuclei to merge into one ball of neutrons: a neutron star. The surface of the neutron star is very hard and as additional matter from the original star continues to fall in and merge into the neutron star, a "traffic jam" occurs and the shockwave resulting from this reflects off the super hard surface of the neutron star, driving the supernova explosion. Suddenly everything falling in is now rushing out. This can only occur once.

A star becomes a white dwarf when it exhausts its nuclear fuel and can no longer produce energy through fusion reactions. Gravity causes the core to collapse while the outer layers are expelled into space, leaving behind a dense, Earth-sized remnant known as a white dwarf.

The Orion Nebula was not formed from a single supernova or nova event. It is a stellar nursery where new stars are currently being formed. The nebula is created by the glowing gas and dust illuminated by newly formed stars within it.