That refers to a star that:* Is blue

* Is fairly big

A white dwarf star starts out like a our sun and turns into a white dwarf at the end of the stars life cycle. They have used up all their nuclear energy. At the end of this nuclear burning stage the star expels most to all of its outer materials. This creates what is known as a planetary nebula. The hot core is the only part of the star that remains. Temperatures of the core can and will exceed 100,000 Celsius becoming a very hot white. From this point the star starts to cool down, but that takes a billion years or more.

What happens to stars when they die depends on how massive they are. For instance stars the size of the Sun turn into white dwarfs that eventual cool, Stars about 8*thr size of the Sun explode to form Neutron Stars (Pulsars) and very very big stars explode and leave behind a black hole.

Eventually - and I mean eventually. If a neutron star was formed at the beginning of the Universe, it would still would not be a black dwarf.

In fact it would be a multiple of about 10 times - and that's a guess - the age of the Universe before a neutron star cools sufficiently to become a black dwarf. Probably longer.

The spectral class of a star is dictated by its temperature. Hotter stars around 30,000K and higher tend to appear blue or bluish-white. At the other end of the spectrum, stars around 1,000-2,000K seem red. For more information see spectral classification, theory of stellar evolution, and the H-R diagram.

No. White dwarfs, neutron stars, and black holes are three different things. With the exception of some black holes, all are remnants of the cores of dead stars at various degrees of collapse.

A white dwarf is the remains of a low to medium mass star consisting of atomic nuclei surrounded by electrons from electron shells that were crushed by gravity. White dwarfs can be up to about two times the mass of the sun and are a few thousand miles across, some about the same size as Earth.

A neutron star is a remnant of a massive star that has collapsed even further. In a neutron star the atoms have been crushed so that neutrons are most of what remains. Neutron stars range from 2 to 3 times the mass of the sun and are roughly 12 to 25 miles across.

A black hole is the remains of a very massive star that has completely collapsed into, at least theoretically, an infinitely dense point. Around the black hole is an area where gravity is so strong that nothing can escape, not even light. Stellar mas black holes range from 3 to 30 times the mass of the sun. There are also supermassive black holes, which are millions to billions times the mass of the sun. It is not known how supermassive black holes form.

• A Giant is a star up to 10 times larger than our Sun
• A Super giant is a star 10 times larger than our Sun
• A white dwarf is a stellar remnant about 100 times smaller than our Sun.

As the name white dwarf implies, this is a small type of star, and it has less surface area from which to radiate light, so even if it is hot, and giving off lots of light per square mile, there are fewer square miles than in larger, non-dwarf stars, so there is less total light being emitted.

There are many types of Dwarf stars - all with different diameters. Our Sun is a dwarf star!

A typical neutron star has a diameter of about 24km our Sun has a diameter of 1.392×106 km

So our Sun is about 58,000 times bigger than a neutron star.

A yellow dwarf star, is a star on the main sequence that has a temperature range of between 5,200 to 6,000 Kelvin. It has a spectral class of G or possibly F.

Our Sun is a yellow dwarf - much as you may not believe it, it is a dwarf compared to other stars!!

See related question for a size comparison

From the Wikipedia article: "Most observed white dwarfs have relatively high surface temperatures, between 8,000 K and 40,000 K"

About 0.5 AU, or about half the distance from Earth to the sun.

possibly

Yes you can see a white dwarf star. but you will need a powerful telescope.

The nearest white dwarf to us, is Sirius B at a distance of 8.6 light years. It was first discovered using a 18.5-inch (470 mm) aperture telescope.

Somewhat confusingly, there are no "medium" stars. Stars are either dwarfs or giants.

Dwarf stars (class V) come in all types: O, B, A, F, G, K, and M.

There are also class VII "white dwarfs", probably better called "degenerate dwarfs" which are distinct from AV stars. In the first place, they really are small (about the size of Earth); the smallest red dwarfs are much larger, and even the so-called "brown dwarfs" are around the size of Jupiter (though much more massive). Also, they're not part of the main sequence.

You have the order right!

Yes, a brown dwarf is a star that failed to ignite hydrogen fusion because it did not have enough mass for a strong enough gravitational collapse.

Brown dwarf stars glow dimly with residual heat for a very short time.

Yes, red dwarfs burn their fuel slowly because they have small sizes.

No. A white dwarf is the remnant of a star in which fusion as stopped.

The brightness of a star depends (a) on its temperature, which affects the amount of radiation emitted per square meter, and (b) the total surface area. A white dwarf has a very small surface area - around 1 / 10,000 the area of our Sun.
White dwarf stars are the compressed cores of a dead star, so it is very hot. Since a white dwarf is also small, it emits less light than most stars, so they are dim.

A white dwarf is a star that is dying and is in its final evolutionary stage.

Star

Because a white dwarf star is the core leftover from a bigger star and the core is the densest part of the star so although the star is smaller than the sun it has a similar mass as it is more dense