Astronomy picture of the day 11-11-2014 - Polar Ring Galaxy NGC 660

Polar Ring Galaxy NGC 660
Image Credit: Gemini Observatory, AURA,Travis Rector(Univ. Alaska Anchorage)

Explanation: NGC 660 is featured inthis cosmic snapshot, a sharp composite of broad and narrow band filter image data from the Gemini North telescopeon Mauna Kea. Over 20 million light-years away and swimming within the boundaries of theconstellation Pisces, NGC 660's peculiar appearance marks it asa polar ring galaxy. A rare galaxy type, polar ring galaxies have a substantial population of stars, gas, and dustorbiting in rings nearly perpendicular to the plane of the galactic disk.The bizarre-looking configuration could have been caused by the chance capture of material from a passing galaxy by a disk galaxy, with the captured debris eventually strung out in a rotating ring. The violent gravitational interaction would account for the myriad pinkish star forming regions scattered along NGC 660's ring.The polar ring component can also be used to explore the shape of the galaxy's otherwise unseendark matter halo by calculating thedark matter's gravitational influence on the rotation of the ring and disk. Broader than the disk, NGC 660's ring spans over 50,000 light-years.