NGC 2139

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, IC 2154, 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]

Supernovae

Three supernovae have been observed in NGC 2139:

• Robert Evans and associates discovered SN 1995ad (type II, mag. 14) on 28 September 1995.^[11][12] 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.^[13]
• SN 2022qhy (type Ibn, mag. 15.889) was discovered by ATLAS on 1 August 2022.^[14]
• SN 2023zcu (type II, mag. 19.054) was discovered by ATLAS on 8 December 2023.^[15]