The standard theory says that white dwarfs are the dead cores of main sequence stars. They're out of fuel and cooling off to the background temperature of the Universe. But now observations show that white dwarfs are surprisingly warm, even though they "died" billions of years ago. This could be from an internal process that causes crystals to form and float upward, pushing heavier liquid downward toward the star's center and releasing gravitational energy.
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When a young star begins forming, it's spinning rapidly, surrounded by a flattened disk that grows its future planets. Once the star can ignite fusion in its core, its stellar winds kick in, clearing out the remaining gas and dust, starving its planets for material. Now, JWST has found an older star in this exact phase of the cycle, dispersing its gas into interstellar space. This limits how much larger the planets can become until no material remains.
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When a star like the Sun reaches the end of its life, it becomes a red giant and blows away its outer layers, leaving an exposed core - a white dwarf. What happens to its planets? Some were consumed when it became a red giant; others could spiral inward and impact the star. Astronomers have found white dwarfs that were polluted with metals in the past, but now they've found one with a metal scar on its surface, where a large, metal-rich asteroid crashed onto the surface.
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If predictions are correct, a key outburst star could put on a show in early 2024.
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