Astronomy:Barred spiral galaxy

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Short description: Spiral galaxy with a central bar-shaped structure composed of stars
NGC 1300, viewed nearly face-on; Hubble Space Telescope image

A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars.[1] Bars are found in about two thirds of all spiral galaxies in the local universe,[2] and generally affect both the motions of stars and interstellar gas within spiral galaxies and can affect spiral arms as well.[3][4] The Milky Way Galaxy, where the Solar System is located, is classified as a barred spiral galaxy.[5]

Edwin Hubble classified spiral galaxies of this type as "SB" (spiral, barred) in his Hubble sequence and arranged them into sub-categories based on how open the arms of the spiral are. SBa types feature tightly bound arms, while SBc types are at the other extreme and have loosely bound arms. SBb-type galaxies lie in between the two. SB0 is a barred lenticular galaxy. A new type, SBm, was subsequently created to describe somewhat irregular barred spirals, such as the Magellanic Clouds, which were once classified as irregular galaxies, but have since been found to contain barred spiral structures. Among other types in Hubble's classifications for the galaxies are the spiral galaxy, elliptical galaxy and irregular galaxy.

Although theoretical models of galaxy formation and evolution had not previously expected galaxies becoming stable enough to host bars very early in the universe's history, evidence has recently emerged of the existence of numerous spiral galaxies in the early universe.[6][7][8]

Barred spiral galaxy IC 5201, located more than 40 million light-years from Earth. It was discovered by Joseph Lunt.[9][10]

Bars

Further information: Density wave theory § Galactic spiral arms
Milky Way Galaxy spiral arms – based on WISE data.

Barred galaxies are apparently predominant, with surveys showing that up to two-thirds of all spiral galaxies develop a bar.[2] The creation of the bar is generally thought to be the result of a density wave radiating from the center of the galaxy whose effects reshape the orbits of the inner stars. This effect builds over time to stars orbiting farther out, which creates a self-perpetuating bar structure.[11]

The bar structure is believed to act as a type of stellar nursery, channeling gas inwards from the spiral arms through orbital resonance, fueling star birth in the vicinity of its center.[12] This process is also thought to explain why many barred spiral galaxies have active galactic nuclei, such as that seen in the Southern Pinwheel Galaxy.

Bars are thought to be temporary phenomena in the lives of spiral galaxies; the bar structures decay over time, transforming galaxies from barred spirals to more "regular" spiral patterns. Past a certain size the accumulated mass of the bar compromises the stability of the overall bar structure. Simulations show that many bars likely experience a "buckling" event in which a disturbance in the orbital resonances of stars in the bar structure leads to an inward collapse in which the bar becomes thicker and shorter, though the exact mechanism behind this buckling instability remains hotly debated.[13] Barred spiral galaxies with high mass accumulated in their center thus tend to have short, stubby bars.[14] Such buckling phenomena are significantly suppressed and delayed by the presence of a supermassive black hole in the galactic center but occur nonetheless.[15]

Since so many spiral galaxies have bar structures, it is likely that they are recurring phenomena in spiral galaxy development. The oscillating evolutionary cycle from spiral galaxy to barred spiral galaxy is thought to take on average about two billion years.[16]

Recent studies have confirmed the idea that bars are a sign of galaxies reaching full maturity as the "formative years" end. A 2008 investigation found that only 20 percent of the spiral galaxies in the distant past possessed bars, compared with about 65 percent of their local counterparts.[17]

Grades

NGC 7640 is a barred spiral galaxy in the Andromeda constellation.[18]

The general classification is "SB" (spiral barred). The sub-categories are based on how open or tight the arms of the spiral are. SBa types feature tightly bound arms. SBc types are at the other extreme and have loosely bound arms. SBb galaxies lie in between. SBm describes somewhat irregular barred spirals. SB0 is a barred lenticular galaxy.

Examples

Example Type Image Information
NGC 2787 SB0 SB0 is a type of lenticular galaxy
NGC 4314 SBa 100px
NGC 4921 SBab 100px
Messier 95 SBb 100px
NGC 3953 SBbc 100px
NGC 1073 SBc 100px
Messier 108 SBcd 100px
NGC 2903 SBbc 100px
NGC 5398 SBdm 100px SBdm can also be considered a type

of barred Magellanic spiral

NGC 55 SBm 100px SBm is a type of Magellanic spiral (Sm)

Other examples

Name Image Type Constellation
M58 100px SBc Virgo
M91 100px SBb Coma Berenices
M95 100px SBb Leo
M109 100px SBb Ursa Major
NGC 1300 100px SBbc Eridanus
NGC 7541 100px SB(rs)bcpec Pisces
NGC 1365 100px SBc Fornax
NGC 2217 100px SBa Canis Major
Magellanic Clouds 100px SBm Dorado, Tucana
UGC 12158 100px SB Pegasus
NGC 1512[19] 100px SB(r)ab Horologium

See also

References

  1. ↑ "Barred spiral galaxy" (in en). ScienceDaily. https://www.sciencedaily.com/terms/barred_spiral_galaxy.htm. 
  2. ↑ 2.0 2.1 Eskridge, P. B.; Frogel, J. A. (1999). "What is the True Fraction of Barred Spiral Galaxies?". Astrophysics and Space Science 269: 427–430. doi:10.1023/A:1017025820201. Bibcode: 1999Ap&SS.269..427E. 
  3. ↑ Mihalas, D. (1968). Galactic Astronomy. W. H. Freeman. ISBN 978-0-7167-0326-6. 
  4. ↑ Ferris, Timothy (1998). The Whole Shebang: A State-of-the-Universe(s) Report. Simon & Schuster. ISBN 978-0-6848-3861-8. 
  5. ↑ Gerhard, Ortwin (2002). "Mass distribution in our Galaxy". Space Science Reviews 100 (1–4): 129. doi:10.1023/A:1015818111633. Bibcode: 2002SSRv..100..129G. 
  6. ↑ Milky Way-like galaxy found in the early universe
  7. ↑ Costantin, Luca; Pérez-González, Pablo G.; Guo, Yuchen; Buttitta, Chiara; Jogee, Shardha; Bagley, Micaela B.; Barro, Guillermo; Kartaltepe, Jeyhan S. et al. (2023). "A Milky Way-like barred spiral galaxy at a redshift of 3" (in en). Nature 623 (7987): 499–501. doi:10.1038/s41586-023-06636-x. ISSN 1476-4687. PMID 37938777. Bibcode: 2023Natur.623..499C. 
  8. ↑ Guo, Yuchen; Jogee, Shardha; Finkelstein, Steven L.; Chen, Zilei; Wise, Eden; Bagley, Micaela B.; Barro, Guillermo; Wuyts, Stijn et al. (2023-03-01). "First Look at z > 1 Bars in the Rest-frame Near-infrared with JWST Early CEERS Imaging" (in en). The Astrophysical Journal Letters 945 (1): L10. doi:10.3847/2041-8213/acacfb. ISSN 2041-8205. Bibcode: 2023ApJ...945L..10G. 
  9. ↑ Steinicke, Wolfgang. "Joseph Lunt". NGC/IC observers. http://www.klima-luft.de/steinicke/ngcic/persons/lunt.htm. 
  10. ↑ "A closer look at IC 5201". https://www.spacetelescope.org/images/potw1650a/. 
  11. ↑ Bournaud, F.; Combes, F. (2002). "Gas accretion on spiral galaxies: Bar formation and renewal". Astronomy and Astrophysics 392 (1): 83–102. doi:10.1051/0004-6361:20020920. Bibcode: 2002A&A...392...83B. 
  12. ↑ Knapen, J. H.; Pérez-Ramírez, D.; Laine, S. (2002). "Circumnuclear regions in barred spiral galaxies — II. Relations to host galaxies". Monthly Notices of the Royal Astronomical Society 337 (3): 808–828. doi:10.1046/j.1365-8711.2002.05840.x. Bibcode: 2002MNRAS.337..808K. 
  13. ↑ Lokas, Ewa L. (2019-09-06). "Anatomy of a buckling galactic bar". Astronomy & Astrophysics 629: A52. doi:10.1051/0004-6361/201936056. ISSN 0004-6361. Bibcode: 2019A&A...629A..52L. 
  14. ↑ Barred Spirals Come and Go, Sky and Telescope, April 2002
  15. ↑ Wheeler, Vance; Valluri, Monica; Silva, Leandro Beraldo e; Dattathri, Shashank; Debattista, Victor P. (2023-11-16). "Early-growing Supermassive Black Holes Strengthen Bars and Boxy/Peanut Bulges" (in en). The Astrophysical Journal 958 (2): 119. doi:10.3847/1538-4357/ace962. ISSN 0004-637X. Bibcode: 2023ApJ...958..119W. 
  16. ↑ Ripples in a Galactic Pond , Scientific American, October 2005
  17. ↑ Sheth, Kartik; Elmegreen, Debra Meloy; Elmegreen, Bruce G. et al. (2008). "Evolution of the Bar Fraction in COSMOS: Quantifying the Assembly of the Hubble Sequence". The Astrophysical Journal 675 (2): 1141–1155. doi:10.1086/524980. ISSN 0004-637X. Bibcode: 2008ApJ...675.1141S. 
  18. ↑ "A spiral in Andromeda". https://www.spacetelescope.org/images/potw1706a/. 
  19. ↑ "Galactic David and Goliath" (in en-GB). http://www.spacetelescope.org/news/heic1712/. 



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