Messier 87

Lore & Background

Messier 87 is a supergiant elliptical galaxy located in the constellation Virgo, containing several trillion stars and ranking among the largest and most massive galaxies in the local universe. It hosts an unusually high number of globular clusters—roughly 15,000, compared to the 150–200 orbiting the Milky Way—and features a prominent jet of energetic plasma that emerges from its core and extends outward at relativistic speeds. The galaxy is one of the brightest radio sources in the sky and is a frequent target for both amateur and professional astronomers. Unlike spiral galaxies, M87 lacks distinctive dust lanes and has an almost featureless, ellipsoidal shape typical of giant ellipticals, with its luminosity and stellar density decreasing steadily from the center.

Its stars form about one-sixth of its total mass and are distributed in a nearly spherically symmetric manner. At its core lies an active supermassive black hole, which was imaged in 2017 by the Event Horizon Telescope, with the final processed image released in April 2019; a subsequent polarized image in March 2021 offered further insight into the forces behind quasars. The galaxy is a strong multi-wavelength emitter, especially in radio waves, and has an isophotal diameter with a diffuse envelope extending to a radius where it appears truncated, possibly due to an encounter with another galaxy. Its interstellar medium is composed of diffuse gas enriched by elements from evolved stars.

Reader's Guide

M87 is a supergiant elliptical galaxy in Virgo containing several trillion stars, making it one of the most massive galaxies in the local universe. Its behavior is dominated by an active supermassive black hole at the core, which powers a relativistic jet of energetic plasma extending at least a certain distance and traveling at relativistic speeds. This jet, first noted as a "curious straight ray" in 1918, is a strong radio source and makes M87 one of the brightest radio sources in the sky.

The galaxy hosts an unusually large population of about 15,000 globular clusters, far exceeding the Milky Way's 150–200. Its ellipsoidal shape lacks distinctive dust lanes, with stars distributed nearly spherically and density decreasing from the core. The interstellar medium contains diffuse gas enriched by elements from evolved stars.

M87's significance extends to its role as a testing ground for measuring supermassive black hole masses; stellar-dynamical modeling in 1978 suggested a central mass of five billion solar masses. In 2019, the Event Horizon Telescope released the first direct image of this black hole, and a polarized image followed in 2021, helping reveal forces behind quasars. As the second-brightest galaxy in the northern Virgo Cluster, it remains a popular target for amateur and professional astronomers studying active galactic nuclei and multi-wavelength radiation.