Pulsating variable stars, powerful tools for galactic structure and evolution

INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
e-mail: gisella.clementini@oabo.inaf.it

Abstract

Pulsating variable stars are powerful tools to study the structure and evolution of galaxies. Among different types of pulsating variables the Classical Cepheids trace the young stellar component in galaxies, and are one of the most important primary stellar distance indicators in establishing the cosmic distance scale. Instead, the RR Lyrae stars, with ages comparable to the age of the Universe, eyewitnessed the processes occurring in the very early times of galaxy formation, and thus can provide hints on how galaxies have formed. The role played by the pulsating variable stars in our understanding of the galactic structure and evolution is briefly reviewed in light of the promises of the scientific exploitation of the Gaia mission.