The black hole at the center of the galaxy M87 is called M87*. The asterisk distinguishes the black hole from its host galaxy, Messier 87, which is also commonly abbreviated as M87. The name follows astronomical naming conventions that use the galaxy designation plus an asterisk for its central compact object.
M87* is a supermassive black hole with a mass billions of times greater than the Sun’s. It lies roughly 55 million light-years away in the constellation Virgo and powers a gigantic relativistic jet of plasma extending thousands of light-years from the galaxy’s core.
M87* became famous when the Event Horizon Telescope released the first horizon-scale black-hole image in 2019. The image showed the black hole’s dark shadow surrounded by an asymmetric glowing ring of hot gas. A common mix-up is answering “M87,” but that is the name of the galaxy, not the formal designation of the black hole. NGC 4889 and Centaurus A are different astronomical objects with their own central black holes.