Type

Stellar mass

Location

In the constellation Ursa Major

Finder Chart

Distance

6,000 light-years

Mass

7 times the mass of the Sun

Size

Diameter 26 miles (42 km), equal to the size of a large city.

Discovery Methods

• Measuring the motions of stars
• Measuring X-rays

Measuring the motions of stars

Because a black hole is both massive and compact, it exerts a strong gravitational pull on the material around it. Astronomers can deduce the presence of a supermassive black hole in the core of a galaxy by measuring the velocities of stars that orbit the black hole. A more-massive black hole will accelerate nearby stars to greater speeds, so the velocities of stars can reveal not only the presence of a black hole, but its mass as well.

More about black hole discovery methods »

This document was last modified: November 19, 2009.