What is the approximate mass of the supermassive black hole M87*?

The supermassive black hole M87* has an approximate mass of 6.5 billion solar masses.

The estimate comes from observations of stars and gas moving under the gravitational influence of the compact object at the center of Messier 87. The Event Horizon Telescope used this mass estimate, together with the galaxy’s distance, to predict the angular size of the black-hole shadow.

M87* is one of the most massive black holes in the nearby universe. Its enormous gravity is associated with a relativistic jet that extends far beyond the central region of the galaxy. The black hole’s mass also helps explain why its shadow was large enough for the global radio telescope array to resolve.

A solar mass is a unit equal to the mass of the Sun. The value is an estimate rather than a direct weighing, and different modeling methods can produce somewhat different uncertainties.