Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2003 January 16
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NGC 1700: Elliptical Galaxy and Rotating Disk
Credit: Thomas S. Statler, Brian R. McNamara (Ohio Univ.), CXC, NASA

Explanation: In spiral galaxies, majestic winding arms of young stars and interstellar gas and dust rotate in a disk around a bulging galactic nucleus. Elliptical galaxies seem to be simpler, randomly swarming with old stars and lacking gas and dust. So astronomers were excited to find that NGC 1700, a young elliptical galaxy about 160 million light-years away, shows evidence for a 90,000 light-year wide rotating disk of multi-million degree hot gas. The evidence comes from data recorded by the orbiting Chandra Observatory, whose sharp x-ray image of NGC 1700 is seen above. Balancing gravity, the rotation of the x-ray hot disk, the largest of its type yet discovered, gives the galaxy a pronounced boxy profile in this false-color picture. Theories about the origin of the disk suggest that NGC 1700 may be the result of a cosmic scale galactic merger, perhaps between a spiral and elliptical galaxy. NGC 1700 is just visible with small telescopes toward the flowing constellation Eridanus.

Tomorrow's picture: bubbling up

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