Messier 84
Messier 84 or M84, also known as NGC 4374, is a giant elliptical or lenticular galaxy in the constellation Virgo. Charles Messier discovered the object in 1781 in a systematic search for "nebulous objects" in the night sky. It is the 84th object in the Messier Catalogue and in the heavily populated core of the Virgo Cluster of galaxies, part of the local supercluster.
| Messier 84 | |
|---|---|
Galaxy Messier 84 in Virgo, imaged by the Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Constellation | Virgo |
| Right ascension | 12h 25m 03.74333s |
| Declination | +12° 53′ 13.1393″ |
| Redshift | 1,060±6 km/s |
| Heliocentric radial velocity | 999 km/s |
| Distance | 54.9 Mly (16.83 Mpc) |
| Apparent magnitude (V) | 9.1 |
| Absolute magnitude (V) | −22.41±0.10 |
| Characteristics | |
| Type | E1 |
| Apparent size (V) | 6.5′ × 5.6′ |
| Half-light radius (apparent) | 72.5″±6″ |
| Other designations | |
| M84, NGC 4374, PGC 40455, UGC 7494, VCC 763 | |
This galaxy has morphological classification E1, denoting it has flattening of about 10%. The extinction-corrected total luminosity in the visual band is about 7.64×1010 L☉. The central mass-to-light ratio is 6.5, which, to a limit, steadily increases away from the core. The visible galaxy is surrounded by a massive dark matter halo.
Radio observations and Hubble Space Telescope images of M84 have revealed two jets of matter shooting out from its center as well as a disk of rapidly rotating gas and stars indicating the presence of a 1.5 ×109 M☉ supermassive black hole. It also has a few young stars and star clusters, indicating star formation at a very low rate. The number of globular clusters is 1,775±150, which is much lower than expected for an elliptical galaxy.
Viewed from Earth its half-light radius, relative angular size of its 50% peak of lit zone of the sky, is 72.5″, thus just over an arcminute.
Two supernovae have been observed in M84: SN 1957B and SN 1991bg. Seen between these dates, it may have bore a third, SN 1980I – which may have been in either neighboring galaxy NGC 4387 or M86. This high rate of supernovae is rare for elliptical galaxies, which may indicate there is a population of stars of intermediate age in M84.