Variable Stars from Eric Weisstein's World of Astronomy Pulsating Variable Stars - Pulsating variable stars are intrinsic variables as their variation in brightness is due to a physical change within the star. In the case of pulsating variables this is due to the periodic expansion and contraction of the surface layers of the stars. This means the star actually increases and decreases in size periodically. The different types of pulsating variable are distinguished by their periods of pulsation and the shapes of their light curves. These in turn are a function of the mass and evolutionary stage of a given star. The American Association of Variable Star Observers (AAVSO) - Variable stars are stars that change in brightness. These brightness changes can range from a few hundredths to as much as twenty magnitudes over periods of a fraction of a second to years, depending on the type of variable star. Stars change in brightness when they are very young, or when they are very old or dying.   Star Charts Astronomical Headlines - This page contains brief information on recent astronomical discoveries as reported in the International Astronomical Union Circulars (IAUCs).     List of Recent Supernovae     How to Report a Discovery Variable Stars: In the footsteps of John Goodricke - The sky is full of variable stars and many of them are regularly observed by professional and amateur astronomers. This project will give you the chance to contribute actively to such observations, by making your own brightness estimates of one or more selected objects! Interactive Star Atlas     Object Catalogues: Named Stars     Object Catalogues: Navigation Stars Martin Nicholson's Semi Regular Stars - Semiregular variable stars are giants or supergiants of intermediate and late spectral type showing considerable periodicity in their light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20 to more than 2000 days, while the shapes of the light curves may be rather different and variable with each cycle. The amplitudes may be from several hundredths to several magnitudes (usually 1-2 magnitudes in the V filter). Variable Star Network - Data distribution, alert on the discovery of supernovae, novae, rare outbursts, discovery of new variable star, dramatic change of known variable stars, general information, complied data, preprints, and distributing finding charts.     © Copyright 2009 - Samuel J. Wormley   by swormley1@gmail.com