Polar-ring galaxy
A polar-ring galaxy is a relatively rare type of galaxy, with only around 100 examples known. The best known polar-ring galaxy is NGC 4650A. It is theorized that these galaxies are formed by the collision of two separate galaxies. The collision results in a structure composed of two rings of material rotating at an approximate right angle to each other.
Formation of polar-ring galaxies
It is important to understand that the collision occurs so slowly that even over a lifetime, the movement is almost imperceptible. Also important is that once what is left of the interacting galaxy has gone on after the collision, the remaining static galaxy does not simply stop moving. The stars in the galaxy will continue on their new paths until they are dispersed and it is no longer a galaxy. What one sees when they look at a polar-ring galaxy is a freeze-frame of a former galaxy spilling out around itself, its stars destined to disperse over many light-years.
List of polar-ring galaxies
| Category | Names of objects |
|---|---|
| Kinematically confirmed polar-ring galaxies | A 0136-0801, ESO 415-G26, Helix Galaxy, UGC 7576, NGC 4650A, UGC 9796 |
| Candidates for polar-ring galaxies | IC 51, A 0113-5442, IC 1689, A 0336-4905, A 0351-5458, AM 0442-622, Abell 548-71,AM 063-371, UGC 5119, A 0950-2234, UGC 5600, ESO 503-G17, Abell 1631-14, Abell 1644-105, A 1256-1710, NGC 5122, UGC 9562, AM 1934-563, AM 2020-504, A 2135-2132, ESO 603-G21, A 2329-4102, A 2330-3751, A 2333-1637, A 2349-3927, A 2350-4042, ESO 293-IG17 |
References
- Hubblesite.org Retrieved January 2007