Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes

Abstract

Context.The theory of stellar evolution can be more closely tested if we have the opportunity to measure new quantities. Nowadays, observations of galactic RR Lyr stars are available on a time baseline exceeding 100 years. Therefore, we can exploit the possibility of investigating period changes, continuing the pioneering work started by V. P. Tsesevich in 1969.