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Written by spacetravel.org
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Sunday, 24 July 2005 22:36 |
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When a stars fuel runs out, it expands to become a red giant. Later, it collapses to become a white dwarf. Sometimes the collapse squeezes and heats leftover fuel, causing the star to become a red giant a second time. Astrophysicists normally expect the second red giant phase to last about a few hundred years.
A white dwarf, known as Sakurais object, or V4334 Sgr, which reignited as recently as 1996, has now shown signs of reheating. This indicates that it has already passed through the red giant stage. Radio telescope measurements of the star have picked up a crackle characteristic of gases ionizing around it. This means that its temperature must have risen a substantial amount since the late 1990s. University of Manchester researchers have hypothesized that the rapid evolution may have been caused by the inside of the star mixing poorly, which would caused the star to burn only the fuel close to its surface, which would run out quickly.
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