Polar-ring galaxy

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NGC 660 showing Polar-Galaxy Structure NGC 660 Polar Galaxy Gemini Observatory.jpg
NGC 660 showing Polar-Galaxy Structure

A polar-ring galaxy is a type of galaxy with an outer ring of gas and stars that rotates over the poles of the galaxy. [1] These polar rings are thought to form when two galaxies gravitationally interact with each other. One possibility is that a material is tidally stripped from a passing galaxy to produce the polar ring. [2] The other possibility is that a smaller galaxy collides orthogonally with the plane of rotation of the larger galaxy, with the smaller galaxy effectively forming the polar-ring structure. [3]

Contents

The best-known polar-ring galaxies are S0s (lenticular galaxies), but from the physical point of view they are part of a wider category of galaxies, including several ellipticals.

The first four S0 galaxies that were identified as polar-ring galaxies were NGC 2685, [4] NGC 4650A, [5] [6] A 0136 -0801, [3] and ESO 415 -G26. [6] While these galaxies have been extensively studied, many other polar-ring galaxies have since been identified. [7] Polar-ring S0 galaxies 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. [7]

The first polar-ring elliptical galaxies were identified in 1978. They were NGC 5128, NGC 5363, NGC 1947 and Cygnus A, [8] while the polar-ring S0 galaxies NGC 2685 and NGC 4650A were at that time indicated as resulting from similar formation processes. [8] Only some years later, when the first observations of the stellar and gas motion of polar-ring elliptical and S0 galaxies were possible with a better spectroscopic technology, the external origin of the gaseous rings was clarified. [3] [6] [9] [10] In addition to the best-known example, NGC 5128 (Cen A), a very regular polar ring elliptical, is NGC 5266 [10]

SPRC (Old Version)

The SPRC is the Sloan Polar-Ring Catalogue, an atlas of 157 polar-ring galaxies. It was put together with images from the Sloan Digital Sky Survey.There are four sections (A, B, C, and D). There are 6 galaxies in section A which are kinematically confirmed galaxies. There are 27 in section B, which are good candidates. In section C, there are 73 galaxies, which are possible candidates. And there are 51 galaxies in section D, which are related objects.

SPRC (New Version)

There is a revised version of the SPRC, with 275 candidates. There are 70 of the best candidates, 115 good candidates, 53 related objects, and 37 face-on rings.

See also

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<span class="mw-page-title-main">Elliptical galaxy</span> Spherical or ovoid mass of stars

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<span class="mw-page-title-main">Lenticular galaxy</span> Class of galaxy between an elliptical galaxy and a spiral galaxy

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<span class="mw-page-title-main">Centaurus A</span> Radio galaxy in the constellation Centaurus

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<span class="mw-page-title-main">NGC 3115</span> Galaxy in the constellation Sextans

NGC 3115 is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from Earth, it is several times bigger than the Milky Way. It is a lenticular (S0) galaxy because it contains a disk and a central bulge of stars, but without a detectable spiral pattern. NGC 3115 is seen almost exactly edge-on, but was nevertheless mis-classified as elliptical. There is some speculation that NGC 3115, in its youth, was a quasar.

<span class="mw-page-title-main">NGC 4526</span> Lenticular galaxy in the constellation Virgo

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<span class="mw-page-title-main">NGC 4650A</span> Polar-ring galaxy in the constellation Centaurus

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<span class="mw-page-title-main">NGC 1553</span> Galaxy in the constellation Dorado

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<span class="mw-page-title-main">NGC 6166</span> Galaxy in the constellation Hercules

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<span class="mw-page-title-main">NGC 4458</span> Galaxy in the Virgo constellation

NGC 4458 is an elliptical galaxy located about 54 million light-years away in the constellation of Virgo. It was discovered by astronomer William Herschel on April 12, 1784. NGC 4458 is a member of Markarian's Chain which is part of the Virgo Cluster. It is in a pair with the galaxy NGC 4461. NGC 4458 and NGC 4461 are interacting with each other.

<span class="mw-page-title-main">NGC 3081</span> Galaxy in the constellation Hydra

NGC 3081 is a barred lenticular ring galaxy in the constellation of Hydra. NGC 3081 is located about 85 million light-years away from Earth, which means, given its apparent dimensions, that NGC 3081 is approximately 60,000 light-years across. It is a type II Seyfert galaxy, characterised by its bright nucleus. It was discovered by William Herschel on 21 December 1786.

<span class="mw-page-title-main">NGC 708</span> Galaxy in the constellation Andromeda

NGC 708 is an elliptical galaxy located 240 million light-years away in the constellation Andromeda and was discovered by astronomer William Herschel on September 21, 1786. It is classified as a cD galaxy and is the brightest member of Abell 262. NGC 708 is a weak FR I radio galaxy and is also classified as a type 2 Seyfert galaxy.

<span class="mw-page-title-main">NGC 1326</span> Galaxy in the constellation Fornax

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<span class="mw-page-title-main">NGC 4324</span> Galaxy in the constellation of Virgo

NGC 4324 is a lenticular galaxy located about 85 million light-years away in the constellation Virgo. It was discovered by astronomer Heinrich d'Arrest on March 4, 1862. NGC 4324 has a stellar mass of 5.62 × 1010M☉, and a baryonic mass of 5.88 × 1010M☉. The galaxy's total mass is around 5.25 × 1011M☉. NGC 4324 is notable for having a ring of star formation surrounding its nucleus. It was considered a member of the Virgo II Groups until 1999, when its distance was recalculated and it was placed in the Virgo W Group.

<span class="mw-page-title-main">NGC 1570</span> Galaxy in the constellation of Caelum

NGC 1570, mistakenly called NGC 1571, is a faint galaxy located in the southern constellation Caelum, the chisel. It has a blue magnitude of 13.2, making it visible through a medium sized telescope. Based on a redshift of z = 0.014760, the object is estimated to be 198 million light years away from the Local Group. It appears to be receding with a heliocentric radial velocity of 4,392 km/s.

References

  1. ↑ James Binney; Michael Merrifield (1998). Galactic Astronomy. Princeton, New Jersey: Princeton University Press. ISBN   0-691-00402-1.
  2. ↑ Ristea, Andrei (2023). "The SAMI Galaxy Survey: physical drivers of stellar-gas kinematic misalignments in the nearby Universe". Monthly Notices of the Royal Astronomical Society. 517 (2): 2677. arXiv: 2210.01147 . doi:10.1093/mnras/stac2839.
  3. 1 2 3 F. Schweizer; B. C. Whitmore; V. C. Rubin (1983). "Colliding and merging galaxies. II - S0 galaxies with polar rings". Astronomical Journal. 88: 909–925. Bibcode:1983AJ.....88..909S. doi: 10.1086/113377 .
  4. ↑ P. L. Schecter; J. E. Gunn (1978). "NGC 2685 - Spindle or pancake". Astronomical Journal. 83: 1360–1362. Bibcode:1978AJ.....83.1360S. doi:10.1086/112324.
  5. ↑ J. L. Sérsic (1967). "Southern Peculiar Galaxies III". Zeitschrift für Astrophysik. 67: 306–311. Bibcode:1967ZA.....67..306S.
  6. 1 2 3 B. C. Whitmore; D. B. McElroy; F. Schweizer (1987). "The shape of the dark halo in polar-ring galaxies". Astrophysical Journal. 314: 439–456. Bibcode:1987ApJ...314..439W. doi:10.1086/165077.
  7. 1 2 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. Bibcode:1990AJ....100.1489W. doi: 10.1086/115614 .
  8. 1 2 Bertola, F. & Galletta, G. (1978). "A new type of galaxy with prolate structure". Astrophysical Journal. 226: L115–L118. Bibcode:1978ApJ...226L.115B. doi: 10.1086/182844 .,
  9. ↑ Bertola, F.; Galletta, G.; Zeilinger, W.~W. (1985). "Warped dust lanes in elliptical galaxies - Transient or stationary phenomena?". Astrophysical Journal. 292: L51–L55. Bibcode:1985ApJ...292L..51B. doi:10.1086/184471.
  10. 1 2 Varnas, S.R. Bertola; F., Galletta; G., Freeman; K.C., Carter, D. (1987). "NGC 5266 - an elliptical galaxy with a dust ring". Astrophysical Journal. 313: 69–88. Bibcode:1987ApJ...313...69V. doi:10.1086/164949.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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