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How long does a white dwarf exist?

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When smaller stars reach the end of their long evolutions —those up to eight times as massive as our own sun—typically become white dwarfs. These ancient stars are incredibly dense. read more

Estimating how long white dwarfs have been cooling can help astronomers learn much about the age of the universe. But not all white dwarfs will spend many millennia cooling their heels. Those in a binary star system may have a strong enough gravitational pull to gather in material from a neighboring star. read more

The metal-rich white dwarf WD 1145+017 is the first white dwarf observed with a disintegrating minor planet which transits the star. The disintegration of the planetesimal generates a debris cloud which passes in front of the star every 4.5 hours, causing a 5-minute-long fade in the star's optical brightness. read more

Eventually—over tens or even hundreds of billions of years—a white dwarf cools until it becomes a black dwarf, which emits no energy. Because the universe's oldest stars are only 10 billion to 20 billion years old there are no known black dwarfs—yet. read more

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