Polar-ring galaxy: Difference between revisions
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[[Image:NGC 4650A I HST2002.jpg|right|thumb|140px|[[NGC 4650A]] is one example of a polar-ring galaxy]] | [[Image:NGC 4650A I HST2002.jpg|right|thumb|140px|[[NGC 4650A]] is one example of a polar-ring galaxy]] | ||
A '''polar-ring galaxy''' is a type of [[galaxy]] in which an outer ring of gas and stars rotates over the poles of the galaxy.<ref name="binneymerrifield1998" | A '''polar-ring galaxy''' is a type of [[galaxy]] in which an outer ring of gas and stars rotates over the poles of the galaxy.<ref name="binneymerrifield1998">{{cite book | ||
| author=James Binney, Michael Merrifield | | author=James Binney, Michael Merrifield | ||
| year=[[1998]] | | year=[[1998]] | ||
Revision as of 09:23, 11 May 2007
A polar-ring galaxy is a type of galaxy in which an outer ring of gas and stars rotates over the poles of the galaxy.[1] Polar rings may be found around 0.5% of all nearby lenticular galaxies, and it is possible that 5% of lenticular galaxies may have had polar rings at some point during their lifetimes.[2] 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.
The first four galaxies that were identified as polar-ring galaxies were NGC 2685,[3] NGC 4650A,[4][5] A 0136 -0801,[6] and ESO 415 -G26.[5] While these galaxies have been extensively studied, many other polar-ring galaxies have since been identified.[2]
References
- ↑ James Binney, Michael Merrifield (1998). Galactic Astronomy. Princeton, New Jersey: Princeton University Press. ISBN 0-691-00402-1.
- ↑ 2.0 2.1 B. C. Whitmore, R. A. Lucas, D. B. McElroy, T. Y. Steiman-Cameron, P. D. Sackett, R. P. Olling (1990). "New observations and a photographic atlas of polar-ring galaxies". Astronomical Journal 100: 1489-1522, 1721-1755. http://adsabs.harvard.edu/abs/1990AJ....100.1489W.
- ↑ P. L. Schecter, J. E. Gunn (1978). "NGC 2685 - Spindle or pancake". Astronomical Journal 83: 1360-1362. http://adsabs.harvard.edu/abs/1978AJ.....83.1360S.
- ↑ J. L. Sérsic (1967). "Southern Peculiar Galaxies III". Zeitschrift für Astrophysik 67: 306-311. http://adsabs.harvard.edu/abs/1967ZA.....67..306S.
- ↑ 5.0 5.1 B. C. Whitmore, D. B. McElroy, F. Schweizer (1987). "The shape of the dark halo in polar-ring galaxies". Astrophysical Journal 314: 439-456. http://adsabs.harvard.edu/abs/1987ApJ...314..439W.
- ↑ F. Schweizer, B. C. Whitmore, V. C. Rubin (1983). "Colliding and merging galaxies. II - S0 galaxies with polar rings". Astronomical Journal 88: 909-925. http://adsabs.harvard.edu/abs/1983AJ.....88..909S.