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] |
Heliocentric 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]
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] |
Heliocentric 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]