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.
References in periodicals archive ?
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.
Gemini's incredible definition of the active star forming regions strewn through the polar ring in NGC 660, juxtaposed against the exquisite crossing dust lanes, is simply beautiful.
But the monkey wrench is the uniquely high gas content of both NGC 660's disk component and its polar ring.
A tidal accretion event will place gas in the polar ring without strongly interacting with the original gas rich host," Svoboda explains.
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.
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.
The beauty of the polar ring is that its orbit is out of the plane of the galaxy,' Schechter says.
I think that's the reason polar rings are relatively rare,' he says.
The experiment, described in the March 15 ASTROPHYSICAL JOURNAL, compared rotational velocities in the polar rings and the S0 disks, and showed that they were about the same at equal distances from the center, thus suggesting the spherical distribution of dark matter.
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.