Eclipsing binaries<\/em><\/strong> show predictable light curves, since they have a drop in brightness when a component of a double star is in front of or behind its companion. The best known representative of this class is Algol (\u03b2 Persei, the \u201eDemon Star in Perseus\u201c). Its brightness decreases every 2.87 days for 10 hours from 2.1 to 3.4m<\/sup>.<\/p>\n Pulsating stars<\/em><\/strong> are stars whose diameter changes regularly. Long period variables (so-called Mira stars) are old red giant stars such as Mira (\u03bf Ceti), whose brightness varies over 80-1,000 days by up to ten magnitudes. The period between two maxima is not always exactly the same. The short period Cepheids are bright, pulsating super giants. They show a fixed relationship between period and absolute brightness and can be used to measure distances to star clusters. The namesake of this class is \u03b4 Cephei, its brightness varies within 5.4 days from 3.6 to 4.4m<\/sup>.<\/p>\n Eruptive variables<\/em><\/strong> show the most unpredictable brightness variations. This class contains novae and supernovae as well as very young stars or the R Coronae Borealis stars, where dark soot clouds conceal the view on the surface.<\/p>\n","protected":false},"excerpt":{"rendered":" The observation of variable stars is the most fertile area for cooperation between professional and amateur astronomers. Many stars change their brightness over time either because they are obscured by a close companion star or because of physical processes on or in the star. The large number of variable stars cannot be supervised continually by … Variable Stars<\/span> weiterlesen ![\"Die](\"http:\/\/freebook.fernglas-astronomie.de\/wp-content\/uploads\/2014\/04\/Veraenderliche.jpg\")
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\nFor eclipsing binaries from Algol-type (above) brightness dips in the light curve occur when a star is hidden by its companion. Depending on the orbital inclination and the nature of the two stars, the minima will vary.
\nFor long period variables or in pulsating variables (below), the brightness varies with the diameter of the star.<\/figcaption><\/figure>\n