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RR Lyrae Stars

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Martha L. Hazen

Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138

Abstract

As some of the very oldest stars in our galaxy, the RR Lyrae variables are of interest to astronomers concerned with the evolution of stars, and to those working on stellar pulsation. These variables are also valuable as distance indicators for the systems in which they occur, although, as can be seen below, their exact intrinsic brightness is a subject of considerable discussion at the present time.

In the following discussion, I will first describe some of characteristics of the RR Lyrae stars, and then focus on the history of their discovery. Since RR Lyrae variables are often abundant in globular clusters, I will describe some of the work being done in this area. Finally, I will outline a few of the outstanding problems in RR Lyrae research that are being investigated today.