Imagine the Universe!
Imagine Home | You Be the Astrophysicist! |

Using the fact that Cyg X-1 is in a Binary System to find its Mass

In general, it is not possible to directly determine the mass of a single star from its light alone (though this may soon change as instruments are becoming sensitive enough to measure the second order effect in the relativistic Doppler shift, which can provide the mass). But in the case of a binary system, the mass of the stars can usually be determined, if certain assumptions are made.

Cygnus X-1 is part of a binary, or double star system. Its companion star, HDE 226868, is a BO Supergiant.

Info Click here for more information on Cyg X-1 and its companion star.
Info Click here to go back to your physics textbooks and find how to find the mass of stars in a binary system.

If words seem to be missing from the articles, please read this.

Imagine the Universe! is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Project Leader: Dr. Barbara Mattson
Curator: Meredith Gibb
Responsible NASA Official: Phil Newman
All material on this site has been created and updated between 1997-2014.
This page last updated: Thursday, 18-Jan-2007 16:14:22 EST