Proper motion suggests super-massive galactic nucleus

17 Jun 2002

The first direct measurements of the proper motion of stars at our galaxy's core provides new evidence for the existence there of a black hole.

Researchers Reinhard Genzel and Andreas Eckart of the Max Planck Institute in Garching, Germany have used the New Technology Telescope in Chile to make 5-year sightings of 39 stars near Sagittarius A*, the radio source at the very pivot of the Milky Way.

The proper motions they find are as big as the radial velocities for these stars. This swirl of activity in turn suggests the presence of a 2.5-million-solar-mass dark object (perhaps many small or one large black hole) packed within a 0.1-light-year volume at the galaxy's nucleus.