NGC 2139 is a barred spiral galaxy in the constellation of Lepus.[4] It was discovered on November 17, 1784, by the German-English astronomer William Herschel.[7] The galaxy is located at a distance of 120.6 million light-years (36.98 Mpc) from the Sun and is receding with a radial velocity of 1,836 km/s.[3]
| NGC 2139 | |
|---|---|
 Legacy Surveys DR10 image of NGC 2139 | |
| Observation data (J2000 epoch) | |
| Constellation | Lepus |
| Right ascension | 06h 01m 07.963s[1] |
| Declination | −23° 40′ 20.35″[1] |
| Redshift | 0.006148±0.000017[2] |
| Heliocentric radial velocity | 1,836 km/s[3] |
| Galactocentric velocity | 1,649 km/s[3] |
| Distance | 120.6 Mly (36.98 Mpc)[3] |
| Apparent magnitude (V) | 11.6[4] |
| Apparent magnitude (B) | 11.98[3] |
| Characteristics | |
| Type | SAB(rs)cd[5] |
| Number of stars | 9.1×109 M☉[5] |
| Apparent size (V) | 2.40′ × 1.9′[4] |
| Notable features | Bulgeless |
| Other designations | |
| NGC 2139, LEDA 18258, MCG -04-15-005, PGC 18258[6] | |
The overall form of this galaxy is irregular with spiral arms and the appearance of tidal features, suggesting a potential recent merger event. There is no central bulge of significance.[8] The morphological classification is SAB(rs)cd,[5] which indicates a barred spiral galaxy (SAB) with a transitional inner ring structure (rs) and loosely wound spiral arms (cd). It is a star forming galaxy with a formation rate of 3.8 M☉·yr−1.[5] There is a plume extending to the south of the galaxy.[8]
A luminous filament runs through the center of the galaxy, which includes a small nuclear cluster. This cluster is only 4.1×107 years old with a mass of 8.3×105 M☉.[8] It is offset at a distance of 320 pc from the center of the galaxy and may come to rest there on a time scale of around 100 million years.[9] The cluster is a source of X-ray emission.[10]
During September 1995, a type II supernova was discovered by R. Evans and associates.[11] Designated SN 1995ad, it was positioned in one of the spiral arms, 25″ west and 5″ south of the NGC 2139 nucleus. The recession velocity was consistent with that of the host galaxy.[12]