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[Music Throughout]

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This is not a cosmic jack-o-lantern

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It's an illustration of a rare type of star recently found by NASA's Kepler and Swift missions.

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The stars are spinning so fast they're flattened into pumpkin shapes,

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and have intense X-ray emissions.

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For four years, Kepler monitored a wide patch of the sky...

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... to look for brightness changes caused by exoplanets passing in front of their host stars.

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The Kepler field of view is one of the best-studied parts of the sky.

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So researchers used NASA's Swift to search for X-ray sources Kepler may also have seen in visible light.

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Some of the brightest ones ...

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... turn out to be rapidly spinning stars.

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The most extreme is called KSw 71.

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The sun rotates once every 25 days.

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KSw 71 is 10 times the sun's size and spins 4 times faster.

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It produces 4,000 times the sun's peak X-ray emission.

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Astronomers think it formed from a pair of sun-like stars in a close binary system.

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The stars orbited faster as they grew closer. Eventually they came into contact.

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Then they merged to form a rapidly spinning "pumpkin" star.

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The transition may take 100 million years, making it a relatively brief phase in the star's life.

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The Swift study found 93 X-ray objects. About half were active galaxies.

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The rest were various types of X-ray emitting stars.

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Swift is now studying additional fields imaged during Kepler's extended K2 mission.

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