Stellar evolution in real time: Period variations in galactic RR Lyr stars

TL;DR

This study analyzes over a century of brightness data from 123 galactic RR Lyrae stars to observe their period variations, providing real-time insights into stellar evolution and highlighting the potential of robotic telescopes and satellite data.

Contribution

It presents the first extensive observational evidence of period changes in RR Lyrae stars over a century, comparing observed rates with theoretical predictions and emphasizing new observational tools.

Findings

Evidence of period increases and decreases at constant rates

Observed rates slightly larger than theoretical models predict

High percentage of stars showing period decrease

Abstract

The times of maximum brightness collected in the GEOS RR Lyr database allowed us to trace the period variations of a sample of 123 galactic RRab variables. These data span a time baseline exceeding 100 years. Clear evidence of period increases or decreases at constant rates has been found, suggesting evolutionary effects. The observed rates are slightly larger than those predicted by theoretical models; moreover, there is an unexpected large percentage of RRab stars showing a period decrease. The new possibilities offered by the use of robotic telecopes (TAROTs, REM) and of data from satellite (CoRoT) are expected to speed up the project to measure stellar evolution in real time. It is noteworthy that the outlines of this project have been sketched during several GEOS meetings, where the different knowledge of amateur and professional astronomers found a very profitable synthesis.