X-Ray Binaries and Mass Measurement | AI Learning Guide

We identify black holes in binaries by weighing their invisible partners. Take Cygnus X-1: a blue supergiant orbits an unseen object. Calculations reveal that unseen object weighs about 21 times the mass of our Sun. Since no neutron star can support that much mass, it must be a black hole.

0:00 / 0:00

Auto-play

Measuring Invisible Mass

In an X-ray binary system, a visible star orbits an invisible compact object. By measuring the visible star's orbital velocity and period, we can calculate the mass of the invisible companion using Kepler's laws. If this mass exceeds the TOV limit, it must be a black hole.

Cygnus X-1

Cygnus X-1 was the first widely accepted black hole candidate. Observations showed a blue supergiant orbiting an invisible companion with a mass of approximately 21 solar masses, far exceeding the neutron star limit.