Coordinated Global Time-Series Photometry of Variable Stars: the Whole Earth Telescope

Iowa State University, Ames IA

Investigators

Abstract

AST-0205983 PI Kawaler After decades of progress, many stages of stellar evolution remain only modestly understood. The investigators here will exploit a powerful tool that Nature provides for probing the interiors of stars, namely asteroseismology. At several points in their evolution, stars undergo self-excited nonradial pulsations, which are observable as multiperiodic brightness variations. By observing these variations as continuously as possible for as long as is practical, they resolve the multiple frequencies of variation in these stars. Since each frequency represents a normal-mode of oscillation of the star, by consulting theoretical models they will deduce details of the global and internal structure of these stars with striking detail. Among other things, using asteroseismology they will measure the mass of isolated pulsators to great accuracy, determine where there are structural or compositional changes in the interior of pulsators, and place limits on or actually measure the chemical composition of a pulsator as a function of radius. The success in this project results from the operation of a unique instrument known as the Whole Earth Telescope (WET). The WET is an international partnership of astronomers, distributed around the Earth, who gather continuous time-series brightness measurements of rapidly varying stars and analyze these data to extract the astrophysical insight contained therein. ***