IS THERE A DIFFERENCE IN LUMINOSITY BETWEEN FIELD AND CLUSTER RR LYRAE VARIABLES

Recent Hipparcos results have lent support to the idea that RR Lyrae v ariables in the halo field and in globular clusters differ in luminosi ty by approximate to 0.2 mag. In this Letter, we study the pulsation p roperties of RR Lyrae variables in clusters with distances determined via main-sequence fitting to Hipparcos parallaxes for field subdwarfs and compare them with the properties of field variables also analyzed with Hipparcos. We show that the period-temperature distributions for field and cluster variables are essentially indistinguishable, thus su ggesting that there is no significant difference in luminosity between them.