NGC 4123

NGC 4123 is a modest-sized,^[10] strongly-barred spiral galaxy^[7] located 75 million light-years^[4] away in the equatorial constellation of Virgo. It was discovered February 25, 1784 by William Herschel.^[5] This is a member of the Virgo Cluster, and it belongs to a group of three galaxies.^[11] A companion galaxy, NGC 4116, lies at an angular separation of 14′ to the southwest. There is no indication of an interaction between the two galaxies.^[7] The third member of the group is NGC 4179.^[11]

Hubble Space Telescope image of NGC 4123

NGC 4123
NGC 4123 with Legacy Surveys DR10
Observation data (J2000 epoch)
Right ascension	12h 08m 11.119s[1]
Declination	+02° 52′ 41.78″[1]
Redshift	0.00429±0.00002[2]
Heliocentric radial velocity	1,326[3] km/s
Distance	75 ± 14 Mly (22.9 ± 4.2 Mpc)[4]
Apparent magnitude (V)	11.4[5]
Apparent magnitude (B)	13.10[3]
Characteristics
Type	SBx(rs)ab[6]
Mass/Light ratio	2.25[7] M☉/L☉
Apparent size (V)	1.900′ × 0.646′[8] (NIR)
Other designations
NGC 4123, UGC 7116, PGC 38531, LEDA 38531, Mrk 1466[9]

The morphological classification of NGC 4123 is SBx(rs)ab, which indicates this is a spiral galaxy with a central X-shaped bar (SBx) encircled by an incomplete ring structure (rs) and moderate to tightly wound spiral arms (ab). The plane of the galaxy is inclined at an angle of 46.9° to the line of sight from the Earth. It lacks a large spheroidal bulge at the core, showing only a luminous point-like source.^[10] Blue knots in the outer spiral arms indicate that star formation is ongoing.^[7] The galaxy has a stellar mass of 1.95×10¹⁰ M_☉^[6] with a star formation rate of 3.429±3.281 M_☉·yr⁻¹.^[12] The atomic gas in the galaxy has a mass of 1.06×10¹⁰ M_☉.^[10]

Radio emission has been detected from an HII nucleus, which is consistent with it having a weak active galactic nucleus.^[13] If there is a supermassive black hole at the core, it has an estimated mass of 10⁷ M_☉.^[14]