Astronomy:NGC 3921
| NGC 3921 | |
|---|---|
 NGC 3921, imaged by the Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Constellation | Ursa Major |
| Right ascension | 11h 51m 06.863s[1] |
| Declination | +55° 04′ 43.38″[1] |
| Redshift | 0.019667[2] |
| Helio radial velocity | 5896 km/s[2] |
| Distance | 277.9 Mly (85.19 Mpc)[3] |
| Apparent magnitude (V) | 12.64[4] |
| Apparent magnitude (B) | 13.4[4] |
| Absolute magnitude (V) | −22.09[5] |
| Characteristics | |
| Type | (R')SA0/a(s) pec[2] |
| Size | 180,200 ly (55,240 pc)[2][note 1] |
| Apparent size (V) | 2.1′ × 1.3′ |
| Other designations | |
| Arp 224, UGC 6823, MGC+09-20-009, PGC 37063 | |
NGC 3921 is an interacting galaxy in the northern constellation of Ursa Major. Estimates using redshift put it at about 59 million light years (18 megaparsecs) from Earth.[3] It was discovered on 14 April 1789 by William Herschel,[6] and was described as "pretty faint, small, round" by John Louis Emil Dreyer, the compiler of the New General Catalogue.[7]
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 8×1039 erg/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
- ↑ 1.0 1.1 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 3921". National Aeronautics and Space Administration / Infrared Processing and Analysis Center. http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+3921&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 Crook, Aidan C.; Huchra, John P.; Martimbeau, Nathalie; Masters, Karen L.; Jarrett, Tom; Macri, Lucas M. (2007). "Groups of Galaxies in the Two Micron All Sky Redshift Survey". The Astrophysical Journal 655 (2): 790–813. doi:10.1086/510201. Bibcode: 2007ApJ...655..790C.
- ↑ 4.0 4.1 4.2 "NGC 3921". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+3921.
- ↑ 5.0 5.1 5.2 Schweizer, François; Seitzer, Patrick; Brodie, Jean P. (2004). "Keck Spectroscopy of Two Young Globular Clusters in the Merger Remnant NGC 3921". The Astronomical Journal 128 (1): 202–210. doi:10.1086/421851. Bibcode: 2004AJ....128..202S.
- ↑ Seligman, Courtney. "New General Catalogue objects: NGC 3900 - 3949". http://cseligman.com/text/atlas/ngc39.htm#3921.
- ↑ "Revised NGC Data for NGC 3921 - Hartmut Frommert - SEDS". http://spider.seds.org/ngc/ngc.cgi?NGC+3921.
- ↑ 8.0 8.1 "Evolution in slow motion | ESA/Hubble". 2015. http://www.spacetelescope.org/images/potw1537a/.
- ↑ 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. et al. (2012). "The Nature of the Bright Ulx X-2 in Ngc 3921: Achandraposition Andhstcandidate Counterpart". The Astrophysical Journal 758 (1): 28. doi:10.1088/0004-637X/758/1/28. Bibcode: 2012ApJ...758...28J.
Notes
- ↑ POSS1 103a-O values used.
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