Period Changes in RRc Stars
John R. Percy
Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4, Canada
Received March 30, 2012; revised April 12, 2012; accepted April 12, 2012
We have used (O–C) analysis to study period changes in forty RRc stars in the GEOS (Groupe Européen d'Observation Stellaire) database of times of maximum of RR Lyrae stars. We find that many of the stars show approximately-linear period changes which are in agreement with the predictions of stellar evolution models. Other stars show period changes that are non-linear and/or larger than predicted by evolution models. Further long-term systematic, sustained observations may help to clarify the nature of the non-evolutionary changes.