Type

Stellar mass

Location

in the constellation Aquila

Distance

8,100 light-years (2500 parsecs)

Mass

14 times the mass of the Sun

Size

Diameter roughly 50 miles (85 km) equal to the size of a large city

Discovery Methods

• Detection of a jet
• Detection of an accretion disk
• Measuring the motions of a companion star

Measuring the motions of a companion star

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 stellar-mass black hole (one that is a few times as massive as the Sun) by measuring the velocity of a companion star in a binary system. In a system that contains a black hole and another type of star (one that produces visible light or other forms of energy), the orbital speeds of the two component stars is much greater than in a system with two "normal" stars (stars that are similar to the Sun). Measuring the orbital speeds of the two components in a binary system, along with the distance between the stars, reveals the system's total mass. Using other techniques, astronomers can determine the mass of the luminous companion. By subtracting that from the system's total mass, they can determine the mass of the dark companion, which reveals whether it is a black hole or a less-dense object like a neutron star. This technique is like the one that astronomers use to deduce the masses of planets in solar systems other than our own.

More about black hole discovery methods »

This document was last modified: June 28, 2011.