polar ring

po·lar ring

a thickened, electron-dense ring at the anterior end of certain stages of the Apicomplexa; part of the apical complex characteristic of these sporozoans.
Farlex Partner Medical Dictionary © Farlex 2012
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Among the topics are a forming polar ring galaxy in the deep field of the Fornax Cluster, star formation laws in various types of galaxies and the case of polar ring galaxies, kinematic transitions and streams in galaxy halos, and shapes and colors of galaxies from school to science.
The very rare galaxy NGC 660, which is called a polar ring, can be spotted about 3[degrees] south-east from eta Piscium and only one degree west of the constellation Aries.
The geometry of NGC 660 -- an enormous edge-on polar ring (some 40,000 light-years across) -- contains more gas (and associated star formation) than its host, which strongly suggests a violent formation.
NGC 660's polar ring resolves into hundreds of objects, a considerable part of which are blue and red supergiant stars.
Hempleman-Adams came within 12.9 miles of the geographic North Pole, becoming the first person to fly across the Arctic Ocean and reach the North Polar Ring in a balloon.
Through my 10-inch reflector at high power, the only suggestion of the Helix Galaxy's polar ring is a somewhat greater central width than I might expect otherwise.
He made history by becoming the first person to fly across the Arctic Ocean and reach the North Polar Ring in a balloon - although he ended his journey 12.9 miles short of the geographic North Pole.
"The beauty of the polar ring is that its orbit is out of the plane of the galaxy,' Schechter says.
Precession will cause the gas to spread and, if the gas comes on a polar orbit, after billions of years a polar ring will form.
The polar ring is thought to be the remnants of a merger that took place 2 to 5 billion years ago.
A diffuse polar ring has been detected in NGC 660, a bright starburst galaxy near M74 in Pisces.
These researchers suggest the possible polar rings may be sustained by the gravity of Neptune's large satellite Triton, which travels nearly backward in its orbit and whose surface, bombarded by charged particles trapped in Neptune's magnetic field (if there is one), may in turn supply particles to the rings themselves.