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This is not a cosmic jack-o-lantern
It's an illustration of a rare type of star recently found by NASA's Kepler and Swift missions.
The stars are spinning so fast they're flattened into pumpkin shapes,
and have intense X-ray emissions.
For four years, Kepler monitored a wide patch of the sky...
... to look for brightness changes caused by exoplanets passing in front of their host stars.
The Kepler field of view is one of the best-studied parts of the sky.
So researchers used NASA's Swift to search for X-ray sources Kepler may also have seen in visible light.
Some of the brightest ones ...
... turn out to be rapidly spinning stars.
The most extreme is called KSw 71.
The sun rotates once every 25 days.
KSw 71 is 10 times the sun's size and spins 4 times faster.
It produces 4,000 times the sun's peak X-ray emission.
Astronomers think it formed from a pair of sun-like stars in a close binary system.
The stars orbited faster as they grew closer. Eventually they came into contact.
Then they merged to form a rapidly spinning "pumpkin" star.
The transition may take 100 million years, making it a relatively brief phase in the star's life.
The Swift study found 93 X-ray objects. About half were active galaxies.
The rest were various types of X-ray emitting stars.
Swift is now studying additional fields imaged during Kepler's extended K2 mission.
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