Messier 87 (also known as Virgo A or NGC 4486, and generally abbreviated to M87) is a supergiant elliptical galaxy in the constellation Virgo. One of the most massive galaxies in the local universe, it is notable for its large population of globular clusters—M87 contains about 12,000 compared to the 150-200 orbiting the Milky Way—and its jet of energetic plasma
that originates at the core and extends outward at least 1,500 parsecs
(4,900 light-years), travelling at relativistic speed. It is one of the
brightest radio sources in the sky, and is a popular target for both amateur astronomy observations and professional astronomy study.
French astronomer Charles Messier
discovered M87 in 1781, cataloguing it as a nebulous feature while
searching for objects that would confuse comet hunters. The second
brightest galaxy within the northern Virgo Cluster, M87 is located about 16.4 million parsecs (53.5 million light-years) from Earth. Unlike a disk-shaped spiral galaxy, M87 has no distinctive dust lanes. Instead, it has an almost featureless, ellipsoidal shape typical of most giant elliptical galaxies, diminishing in luminosity with distance from the centre. Forming around one sixth of M87's mass, the stars
in this galaxy have a nearly spherically symmetric distribution, their
density decreasing with increasing distance from the core. At the core
is a supermassive black hole, which forms the primary component of an active galactic nucleus. This object is a strong source of multiwavelength radiation, particularly radio waves.
M87's galactic envelope extends out to a radius of about 150
kiloparsecs (490,000 light-years), where it has been truncated—possibly
by an encounter with another galaxy. Between the stars is a diffuse interstellar medium of gas that has been chemically enriched by elements emitted from evolved stars.
