The central region of a galaxy is often referred to as the galactic center, galactic nucleus, or galactic core. These terms are used interchangeably and refer to the same region.

Spiral galaxies are the most common type of galaxy in the universe. They are characterized by their spiral arms, which are regions of active star formation.

Sagittarius A* is the supermassive black hole at the center of our galaxy. It has a mass of about 4 million times that of the Sun.

The event horizon of a black hole is the boundary beyond which nothing, not even light, can escape. It is the point of no return.

The Schwarzschild radius of a black hole is the radius of the event horizon of a black hole. It is the radius at which the escape velocity from the black hole is equal to the speed of light.

The accretion disk of a black hole is a disk of gas and dust that orbits a black hole. The gas and dust in the accretion disk is heated by friction and emits X-rays and other forms of radiation.

The jet of a black hole is a stream of particles that is ejected from a black hole. The particles in the jet are accelerated to very high energies and can travel over vast distances.

The mass of the supermassive black hole at the center of M87 is 6.5 million solar masses.

The distance from the Earth to the center of our galaxy is 8,000 light-years.

The first black hole that was ever imaged was M87.

The Event Horizon Telescope was the telescope that was used to image M87.

The temperature of the accretion disk of Sagittarius A* is 10 million Kelvin.

The speed of the jet of M87 is 99.9% the speed of light.

The mass of the supermassive black hole at the center of Cygnus X-1 is 15 solar masses.

The name of the star that is closest to Sagittarius A* is S2.