The first decade of RR Lyrae space photometric observations

TL;DR

This paper reviews a decade of space-based photometric observations of RR Lyrae stars, highlighting new insights into their pulsation modes, classifications, and modulation behaviors revealed by high-precision data from MOST, CoRoT, and Kepler.

Contribution

It provides a comprehensive overview of how space telescopes have advanced understanding of RR Lyrae variability, especially regarding additional pulsation modes and star classifications.

Findings

Common additional mode in RRd and RRc stars

Two classes of fundamental-mode RR Lyrae stars

No correlation between modulation periods

Abstract

Space-based photometric telescopes stirred up stellar astrophysics in the last decade, and RR Lyrae stars have not been an exception from that either. The long, quasi-continuous, high-precision data from MOST, CoRoT and Kepler revealed a wealth of new insights about this well-known variable class. One of the most surprising mysteries turned out to be the apparent omnipresence of a common additional mode in all RRd and RRc stars. Moreover, fundamental-mode stars seem to populate two distinct classes, one of which is characterized by the presence of additional modes and/or modulation, and another limited to strict single-mode pulsation. The presence of additional modes and multiple modulations in RRab stars allowed us to construct Petersen diagrams for these parameters: while the pulsation modes show clear structures according to period ratios, there seems to be no relation between the modulation periods themselves.