for Astrophysics, Cambridge, MA 02138
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.