NGC 3921 is the remnant of a
galaxy merger. The two progenitor galaxies are thought to have been
disk galaxies that collided about 700 million years ago.[8] The image shows noticeable
star formation and structures like loops, indicative of galaxies interacting.[8] Because of this, NGC 3921 was included in
Halton Arp's Atlas of Peculiar Galaxies under the designation Arp 224.[4]
Being a
starburst galaxy, NGC 3921 has important features. One of them is an
ultraluminous X-ray source, designated X-2, with an X-ray luminosity of 8×1039erg/s.[9] Additionally, two candidate
globular clusters have been detected within NGC 3921.[5] They are both fairly young, and about half as massive as
Omega Centauri, demonstrating that mergers of gas-rich galaxies can also create more metal-rich globular clusters.[5]
References
^
abSkrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W.; Chester, Thomas; Elias, Jonathan H.; Huchra, John P.; Liebert, James W.; Lonsdale, Carol J.; Monet, David G.; Price, Stephan; Seitzer, Patrick; Jarrett, Thomas H.; Kirkpatrick, J. Davy; Gizis, John E.; Howard, Elizabeth V.; Evans, Tracey E.; Fowler, John W.; Fullmer, Linda; Hurt, Robert L.; Light, Robert M.; Kopan, Eugene L.; Marsh, Kenneth A.; McCallon, Howard L.; Tam, Robert; Van Dyk, Schuyler D.; Wheelock, Sherry L. (1 February 2006).
"The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183.
Bibcode:
2006AJ....131.1163S.
doi:10.1086/498708.
ISSN0004-6256.
S2CID18913331.
^Jonker, P. G.; Heida, M.; Torres, M. A. P.; Miller-Jones, J. C. A.; Fabian, A. C.; Ratti, E. M.; Miniutti, G.; Walton, D. J.; Roberts, T. P. (2012). "The Nature of the Bright Ulx X-2 in Ngc 3921: Achandraposition Andhstcandidate Counterpart". The Astrophysical Journal. 758 (1): 28.
arXiv:1208.4502.
Bibcode:
2012ApJ...758...28J.
doi:
10.1088/0004-637X/758/1/28.
S2CID59330131.