List of ring galaxies

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This is a list of ring galaxies. A ring galaxy, as the name suggests, is a disc or spiral galaxy with its galactic disc structured or distorted into a ring or torus-like appearance. Hoag's Object, discovered by Art Hoag in 1950, is the prototypical example of a ring galaxy. Ring galaxies are theorized to be formed through multiple possible situations-

1. Bar instability – a phenomenon where the rotational velocity of the bar in a barred spiral galaxy increases to the point of spiral spin-out. Under typical conditions, gravitational density waves would favor the creation of spiral arms. When bar instability occurs, these density waves are instead migrated out into a ring-structure by the pressure, force, and gravitational influence of the byronic and dark matter furiously orbiting about the bar. This migration forces the stars, gas and dust found within the former arms into a torus-like region, forming a ring, and often igniting star formation.

2. Galactic collisions- another observed way that ring galaxies can form is through the process of two or more galaxies colliding. The cartwheel galaxy, galaxy pair AM 2026-424, and Arp 147 are all examples of ring galaxies believed to be formed from this process. In pass-through galactic collisions, an often smaller galaxy will pass through the disc of an often larger spiral, causing an outward push of the arms, as if dropping a rock into a pond of still water. In side-swipe and head-on collisions, the appearance of a perfect ring are less likely, with chaotic and warped appearances dominating.

3. Intergalactic medium accretion- this method has been inferred through the existence of Hoags object, along with UV observations of several other large and ultra-large super spiral galaxies and current formation theories of spiral galaxies. UV-light observations show several cases of faint, ring-like and spiral structures of hot young stars that have formed along the network of cooled inflowing gas, extending far from the visible luminous galactic disc. If conditions are favorable, a ring can form in the place of a spiral structure. Since some spiral galaxies are theorized to have formed from massive clouds of intergalactic gas collapsing and then rotationally forming into a disc structure, one could assume that a ring disc could form in place of a spiral disc if, as mentioned before, conditions are favorable. This holds true for protogalaxies, or galaxies just throughout to be forming, and old galaxies that has migrated into a section of space with a higher gas content than its previous locations.

List[edit]

Name Image Catalogue number Distance Notes
Cartwheel Galaxy Sig06-005.jpg ESO 350-40, PGC 2248 500 Mly lenticular galaxy
NGC 6028 SDSS NGC 6028.jpeg NGC 6028, NGC 6046, PGC 56716 203 Mly barred lenticular galaxy
Hoag's Object Hoag's object.jpg PGC 54559, PRC D-51 600 Mly
SDSS J151713.93+213516.8 Mini Hoag.jpg This galaxy can be seen behind Hoag's Object
AM 0644-741 AM 0644-741.jpg AM 0644-741 300 Mly
NGC 1291 NGC 1291 GALEX.jpg NGC 1291, NGC 1269,[1] PGC 012209 33 Mly
NGC 1512 NGC 1512.jpg PGC 14391 38 Mly Galaxy exhibits a double-ring structure
NGC 1533 NGC 1533 .jpg NGC 1533, PGC 14582[2] 62 ± 4 Mly [3]
NGC 2859 UGC 5001, PGC 26649 82.8 Mly lenticular galaxy with ring structure[4]
NGC 1350 Ngc 1350.jpg PGC 013059 87.4 Mly spiral galaxy with ring structure
NGC 4622 NGC 4622HSTFull.jpg PGC 42701 200 Mly unbarred spiral galaxy with ring
NGC 4777 NGC 4777, PGC 43852
NGC 7217 NGC 7217 Hubble.jpg UGC 11914, PGC 68096 50 Mly unbarred spiral galaxy with ring
II Zw 28[5] Zw II 28, 2MASX J05014205+0334278
Mayall's Object Hubble Interacting Galaxy Arp 148 (2008-04-24).jpg Arp 148, VV 032, MCG+07-23-019, APG 148 450 Mly collisional ring galaxy
I Zw 045[6] I Zw 045, NGC 4774 collisional ring galaxy
VII Zw 466[6] VII Zw 466, UGC 07683 collisional ring galaxy
Arp 10[6] Arp 10, UGC 01775, 2MASX J02182639+0539139[7] collisional ring galaxy
Arp 147 Arp 147.jpg IC 298 interacting pair
NGC 4650A NGC 4650A I HST2002.jpg PGC 42951 polar ring galaxy
NGC 660 NGC660.jpg polar ring galaxy
NGC 922 Hubble view of NGC 922.jpg ESO 478-28, ISG 10 150 Mly collisional ring galaxy
PGC 1000714 PGC 1000714 - GALEX.jpg 360 Mly double-ringed galaxy

See also[edit]

References[edit]

  1. ^ "NGC 1291". Capella Observatory. 2005. Retrieved April 1, 2012.
  2. ^ "Results for NGC 1533". NASA/IPAC Extragalactic Database. Retrieved 2008-06-26.
  3. ^ Ryan-Weber, Emma; Webster, Rachel; Bekki, Kenji (April 2003). Jessica L. Rosenberg; Mary E. Putman (eds.). Galactic Recycling: The HI Ring Around NGC 1533. The IGM/Galaxy Connection: the Distribution of Baryons at z=0, ASSL Conference Proceedings. 281. Dordrecht: Kluwer Academic Publishers. p. 223. arXiv:astro-ph/0209321. Bibcode:2003ASSL..281..223R. doi:10.1007/978-94-010-0115-1_40. ISBN 1-4020-1289-6.
  4. ^ "Lenticular Galaxy (NGC 2859)". Calvin College. Retrieved July 28, 2013.
  5. ^ "Hubble Gazes on One Ring to Rule Them All". NASA. March 15, 2013. Retrieved July 28, 2013.
  6. ^ a b c Appleton, P. N.; Struck-Marcell, Curtis (1996). "Collisional Ring Galaxies". Fundamentals of Cosmic Physics. 16: 111–220. Bibcode:1996FCPh...16..111A. Retrieved July 29, 2013.
  7. ^ "UGC 1775". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 29, 2013.