Extrinsic variables have variations in their brightness, as seen by terrestrial observers, due to some external source. One of the most common reasons for this is the presence of a binary companion star, so that the two together form a binary star. When seen from certain angles, one star may eclipse the other, causing a reduction in brightness. One of the most famous eclipsing binaries is Algol, or Beta Persei (β Per).
VSS runs a number of projects related to eclipsing binary systems, which are outlined below.
Older archived projects can be found here:
- Southern Eclipsing Binaries – EB and EW Project
- Southern Eclipsing Binaries – EA Project
- Southern Binaries DSLR Project
- Equatorial Eclipsing Binaries Project