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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.

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Cosmic Collision Forges Galactic Ring

Explanation: How could a galaxy become shaped like a ring? The rim of the blue galaxy pictured on the right is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. That galaxy, AM 0644-741 , is known as a ring galaxy and was caused by an immense galaxy collision. When galaxies collide , they pass through each other -- their individual stars rarely come into contact. The ring -like shape is the result of the gravitational disruption caused by an entire small intruder galaxy passing through a large one. When this happens, interstellar gas and dust become condensed, causing a wave of star formation to move out from the impact point like a ripple across the surface of a pond. The likely intruder galaxy is on the left of this combined image from Hubble ( visible ) and Chandra ( X-ray ) space telescopes. X-ray light is shown in pink and depicts places where energetic black holes or neutron stars , likely formed shortly after the galaxy collision , reside.

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Date September 17, 2018
Credit Image Credit: X-ray: Chandra ( NASA , CXC , INAF , A. Wolter et al. ); Optical: Hubble ( NASA , STScI )
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.