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Arlie Petters studies the shapes that occur when the light rays from a star are bent by the gravity of massive objects. The name for this effect is "Gravitational Lensing". This phenomenon has many interesting manifestations. For example:
- Multiple imaging: more than one image of the same star can reach an observer simultaneously.
- Magnification: distant images can be magnified, making it possible to see stellar objects which would otherwise be too faint.
- Detection of dark matter: if lensing effects are detected, and no lensing object is detected, this is evidence for the presence of "dark matter".
Further information about the work and the career of
Prof. Arlie Pettersis available in his biography.
There is a Scientific American article describing gravitational lensing, and additional material can be found at the CASTLE Survey web site (the CfA-Arizona Space Telescope LEns).
For a technical article that includes background information, see this site at the University of Colorado. Here is a report on a lecture about gravitational lensing at MIRA, the Monterey Institute for Research in Astronomy.
Other good lensing sites are from The University of British Columbia, and Bell Laboratories, from which the following image was taken.
Here is a good demonstration of the phenomenon of gravitational lensing from the Czech Republic which includes a large bibliography of other websites treating this subject.