General Astronomy. Variable Stars. Variable Stars. The observations of differences in the brightness of variable stars, start from the antiquity. In 134 B.C, Iparchus observed the flash of a nova.
The observations of differences in the brightness of variable stars, start from the antiquity.
Ranges from 12th magnitude to nearly 3.5th magnitude over a period of about 406 days (Long Period Variable)
Much of this information comes from the AAVSO web site atwww.aavso.org
These are binary systems of stars with an orbital plane lying near the line-of-sight of the observer.
The components periodically eclipse one another, causing a decrease in the apparent brightness of the system as seen by the observer.
The period of the eclipse, which coincides with the orbital period of the system, can range from minutes to years.
Examples: Algol, Beta Persei
Beta Lyrae (Sheliak) is an eclipsing contact binary star system. Its two component stars are close enough that material from the photosphere of each is pulled towards the other, drawing the stars into an ellipsoid shape. Beta Lyrae is the prototype for this class of eclipsing binaries, whose components are so close together that they deform by their mutual gravitation.
Rotating stars are often binary systems, which undergo small amplitude changes in light that may be due to dark or bright spots or patches on their stellar surface, or may be due to thermal or chemical inhomogeniety of stellar atmospheres caused by magnetic fields.