What is a white dwarf?

What is a white dwarf simple definition?

A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula. Only the hot core of the star remains.

What is a white dwarf made of?

The white dwarf consists of an exotic stew of helium, carbon, and oxygen nuclei swimming in a sea of highly energetic electrons. The combined pressure of the electrons holds up the white dwarf, preventing further collapse towards an even stranger entity like a neutron star or black hole.

Why is it called a white dwarf?

White dwarf stars, so called because of the white colour of the first few that were discovered, are characterized by a low luminosity, a mass on the order of that of the Sun, and a radius comparable to that of Earth.

What is an example of a white dwarf?

The nearest known white dwarf is Sirius B, at 8.6 light years, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910.

What is a white star?

1: a star of spectral type A or F having a moderate surface temperature and a white or yellowish color. 2a: an annual morning glory (Ipomoea lacunosa) of the southern U.S. with star-shaped leaves and small white or purplish flowers. b: a bellflower (Campanula carpatica alba) with white flowers.

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Why are white dwarfs important?

White dwarfs are rich forensic laboratories that provide links between the history and future evolution of the Milky Way Galaxy. The structure and composition of white dwarfs contain the records of the final stages of stellar evolution. UV astronomy is particularly important for the study of white dwarf stars.

How long do white dwarfs live?

The oldest known white dwarfs are about 12 billion years old. For example WD 0346+246 (WD 0346+246 – Wikipedia ). As the universe is 13.7 billion years old, this is close to the maximum possible. White dwarfs usually begin their lives at temperatures about 100,000 K (Kelvin).

Why is a white dwarf still glowing?

The imploded white dwarf has its internal energy compressed into a very small volume. Hence they initially shine at a very high temperature. This is not realistic, for as the white dwarf forms it radiates most of its energy to eject off the outer layers into a nebular cloud.

Are white dwarfs diamonds?

Astronomers aren’t being poetic when they say this star is a diamond. Scientists have identified what is possibly the coldest white dwarf ever detected. In fact, this dim stellar corpse is so cold that its carbon has crystallized, effectively forming a diamond the size of Earth, astronomers said.

How hot is a white dwarf?

Such stars eventually blow off the material of their outer layers, which creates an expanding shell of gas called a planetary nebula. Within this nebula, the hot core of the star remains—crushed to high density by gravity—as a white dwarf with temperatures over 180,000 degrees Fahrenheit (100,000 degrees Celsius).

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Is Sun a white dwarf?

Like all stars, our Sun will go through several stages in its life. At the moment, it is only a middle-aged star, but like most stars, it will eventually become a white dwarf. Our hot Sun has spent the last 5 billion years turning hydrogen into helium.

Are white dwarfs hotter than the sun?

A typical white dwarf has a carbon and oxygen mass similar to the Sun, but is much smaller in size (similar to the Earth). It is much hotter (25,000 K), but because of its small size its luminosity is low.

What is the biggest white dwarf?


Title Star Date
Most massive RE J0317-853 1998
Least massive SDSS J091709.55+463821.8 2007
Largest Z Andromedae B
Smallest RE J0317-853 2010

What is the name of the brightest white dwarf?

White dwarfs may be white and hot, but their small size means that nearly all are faint. But lucky for us, not too faint. The brightest and most familiar is Sirius B at magnitude +8.5. Even at its maximum separation of 11.5″ in 2025, this dwarf’s a tough nut because of the overwhelming glare of Sirius itself.

What happens after a white dwarf?

But the white dwarf remains hot for some time, much like a stove burner still emits heat even when it has been turned off. After an extremely long time, all of the leftover heat will have radiated away. No longer emitting heat or light, the white dwarf will become a black dwarf.

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