Double-Mode Radial Pulsations among RR Lyrae Stars

TL;DR

This paper reports the discovery of 59 new double-mode RR Lyrae stars in the Galactic field and LMC, providing valuable data for understanding horizontal-branch star properties and the mass-metallicity relation.

Contribution

The study presents the identification and analysis of new double-mode RR Lyrae stars, including rare mode-switching objects, and updates the Petersen diagram with these findings.

Findings

Discovery of 59 new Galactic RRd stars.

Verification of RRd stars in the LMC from EROS-II.

Identification of rare triple-mode pulsators.

Abstract

Double-mode RR Lyr type stars are important for studies of properties of horizontal-branch stars. In particular, two periods coupled with spectral properties give a mass estimate that is independent of evolutionary models. Here, we present 59 new Galactic double-mode RR Lyr stars found in the LINEAR survey data with the fundamental radial mode and the first overtone exited (RRd stars). These stars may be useful for constraining the mass-metallicity relation for field horizontal-branch stars. Also, new RRd stars found in the LMC by EROS-II are verified. We present the updated Petersen diagram and the distribution of the fundamental mode periods. Comments on selected variable stars from LINEAR and LMC EROS-II surveys are also presented, including very rare objects: the third known mode-switching RR Lyr and Cepheid pulsating simultaneously in three radial modes.