found: Pulsating variable stars, via Australia Telescope Outreach and Education web site, June 4, 2009(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 decrease in size periodically. The different types of pulsating variable are disthinguished by their periods of pusation and the shapes of their light curves.)
