Messier 84

This article is about the galaxy M84. For the Yugoslav tank, see M-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^[a] in a systematic search for "nebulous objects" in the night sky.^[7] 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.^[8]

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[1]
Declination	+12° 53′ 13.1393″[1]
Redshift	1,060±6 km/s[2]
Heliocentric radial velocity	999[3] km/s
Distance	54.9 Mly (16.83 Mpc)[3]
Apparent magnitude (V)	9.1[4]
Absolute magnitude (V)	−22.41±0.10[5]
Characteristics
Type	E1[5]
Apparent size (V)	6.5′ × 5.6′[2]
Half-light radius (apparent)	72.5″±6″[5]
Other designations
M84, NGC 4374, PGC 40455, UGC 7494, VCC 763[6]

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.^[5]

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_☉^[9] supermassive black hole. It also has a few young stars and star clusters, indicating star formation at a very low rate.^[10] The number of globular clusters is 1,775±150, which is much lower than expected for an elliptical galaxy.^[11]

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.

Supernovae

Three supernovae have been observed in M84:

• SN 1957B (Type Ia, mag. 12.5) was discovered by Howard S. Gates on 28 April 1957, and independently by Dr. Giuliano Romano on 18 May 1957.^[12][13][14]
• SN 1980I (Type Ia, mag. 14) was discovered by M. Rosker on 13 June 1980.^[15][16] Historically, this supernova has been catalogued as belonging to M84, but it may have been in either neighboring galaxy NGC 4387 or M86.^[17]
• SN 1991bg (Type Ia-pec, mag. 14) was discovered by Reiki Kushida on 3 December 1991.^[18][19] This supernova has been studied extensively as a peculiar and underluminous Type Ia, and is now used as a template, with similar events being classified as Type Ia-91bg-like.^[20]

This high rate of supernovae is rare for elliptical galaxies, which may indicate there is a population of stars of intermediate age in M84.^[11]

Location of M84

See also

• List of Messier objects