NGC 3921
| NGC 3921 | |
|---|---|
| 280px
NGC 3921, imaged by the Hubble Space Telescope
|
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| 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] |
| Type | (R')SA0/a(s) pec[2] |
| Size (ly) | 180,200 ly (55,240 pc)[2][note 1] |
| Apparent dimensions (V) | 2.1′ × 1.3′ |
| Apparent magnitude (V) | 12.64[4] |
| Apparent magnitude (B) | 13.4[4] |
| Absolute magnitude (V) | −22.09[5] |
| Other designations | |
| Arp 224, UGC 6823, MGC+09-20-009, PGC 37063 | |
NGC 3921 is a galaxy in the northern constellation of Ursa Major. Estimates using redshift put the galaxy at about 59 million light years (18 megaparsecs) away.[3] It was discovered on 14 April 1789 by William Herschel,[6] and it 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 candidates globular clusters have been detected within NGC 3921.[5] They are both fairly young, and are about half as massive as Omega Centauri: this demonstrates that mergers of gas-rich galaxies can also create more metal-rich globular clusters.[5]
References
- ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 4.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 5.0 5.1 5.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
Notes
- ↑ POSS1 103a-O values used.
