Imagine the Universe!

Two hot blobs orbiting a black hole.
Click on image to
view 2.5 MB animation.
(Credit: NASA/Dana Berry, Skyworks Digital)

An audio signal rises in frequency as the blob comes toward you and falls in frequency as it moves away from you.

This animation illustrates how scientists track the motion of material around a black hole by observing the Doppler shift of spectral lines.

First we see one blob of material. On the graph we see the energy of an emission line emitted from this material. Note how the energy emitted from this material rises to about 6.5 KeV as it moves toward us and then falls to about 5.8 keV as it moves away. This is the Doppler effect - as matter moves around the black hole it is coming toward us and away from us, causing its observed energy to rise and fall. About 14 seconds into the animation, a second blob appears further out from the balck hole. Its energy does not vary as much as the first because it is moving more slowly.

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
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

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