Morphological classification of NGC 4861 has proved relatively difficult. Its mass, size, and rotational velocity are consistent with it being a
spiral galaxy. However, due to its highly irregular shape, it may also be classified as a
dwarf irregular galaxy.[5] In fact, since dwarf galaxies are less massive and have lower
gravitational potentials, gases and other material for
star formation can move within them much faster, causing the galaxy to become a specific type of
starburst galaxy, called a
blue compact dwarf galaxy.[5][3] It has also been described as a "comet-like" galaxy due to its resemblance to a
comet.[6]
Two
ultraluminous X-ray sources (ULXs) have been found within NGC 4861. The first, NGC 4861 X1, is associated with a dense
H II region. The second, NGC 4861 X2, seems to be within a small
star cluster near the "comet head" of NGC 4861. Assuming it is a star cluster, it has a mass of 400±80
M☉ and an age of 5 million years. Compared to other star clusters with which ULXs are associated, its mass is quite low.[6]
^
abcSkrutskie, 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.
^
abEla, M Ozdogan; Akyuz, A.; Aksaker, N.; Avdan, S.; Oralhan, I Akkaya; Vinokurov, A.; Allak, S.; Solovyeva, Y.; Atapin, K.; Bizyaev, D. (2021). "Optical counterparts of ULXs in two dwarf galaxies: NGC 4861 and NGC 4449". Monthly Notices of the Royal Astronomical Society. 505: 771–782.
arXiv:2105.02302.
doi:
10.1093/mnras/stab1321.
Media related to
NGC 4861 at Wikimedia Commons
