Astronomy:NGC 4861
Coordinates: 
12h 59m 02.340s, +34° 51′ 33.98″
| NGC 4861 | |
|---|---|
| File:NGC 4861 - HST- Potw1704a.tif Hubble Space Telescope image of NGC 4861, taken using the Advanced Camera for Surveys | |
| Observation data (J2000 epoch) | |
| Constellation | Canes Venatici |
| Right ascension | 12h 59m 02.340s[1] |
| Declination | +34° 51′ 33.98″[1] |
| Redshift | 0.002785[2] |
| Helio radial velocity | 835[2] |
| Distance | 34.77 ± 15.99 Mly (10.662 ± 4.903 Mpc)[2] |
| Group or cluster | Virgo Cluster |
| Apparent magnitude (V) | 12.32 |
| Apparent magnitude (B) | 12.90 |
| Characteristics | |
| Type | SB(s)m[2] Im/BCD |
| Apparent size (V) | 0.797′ × 0.692′[1] |
| Other designations | |
| Arp 266, UGC 8098, MCG+06-29-003, PGC 44536[3] | |
NGC 4861, also known as Arp 266, is a galaxy in the constellation Canes Venatici. It was discovered by William Herschel on May 1, 1785.[4]
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]
See also
- Dwarf irregular galaxy
References
- ↑ 1.0 1.1 1.2 Skrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W. et al. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal 131 (2): 1163–1183. doi:10.1086/498708. ISSN 0004-6256. Bibcode: 2006AJ....131.1163S. https://ui.adsabs.harvard.edu/abs/2006AJ....131.1163S/abstract.
- ↑ 2.0 2.1 2.2 2.3 "NED results for object NGC 4861". National Aeronautics and Space Administration / Infrared Processing and Analysis Center. http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+4861&extend=no&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES.
- ↑ 3.0 3.1 "NGC 4861". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+4861.
- ↑ Courtney Seligman. "New General Catalog Objects: NGC 4500 - 4599". http://cseligman.com/text/atlas/ngc48a.htm#4861.
- ↑ 5.0 5.1 "Starbirth with a chance of winds?". https://www.spacetelescope.org/images/potw1704a/.
- ↑ 6.0 6.1 Ela, M Ozdogan; Akyuz, A.; Aksaker, N.; Avdan, S.; Oralhan, I Akkaya; Vinokurov, A.; Allak, S.; Solovyeva, Y. et al. (2021). "Optical counterparts of ULXs in two dwarf galaxies: NGC 4861 and NGC 4449". Monthly Notices of the Royal Astronomical Society 505: 771–782. doi:10.1093/mnras/stab1321.
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