Metal-rich or misclassified? The case of four RR Lyrae stars

TL;DR

This study re-examines four RR Lyrae stars, revealing misclassification issues and suggesting some stars are more metal-rich or belong to different pulsation modes than previously thought.

Contribution

The paper identifies misclassified RR Lyrae stars and clarifies their pulsation modes and metallicities using light curve analysis.

Findings

Two stars are RRc pulsators misclassified as RRab.

Photometric metallicities support RRc classification for two uncertain stars.

Some stars are outliers in period-Fourier space, indicating classification challenges.

Abstract

We analysed the light curve of four, apparently extremely metal-rich fundamental-mode RR Lyrae stars. We identified two stars, MT Tel and ASAS J091803-3022.6 as RRc (first-overtone) pulsators that were misclassified as RRab ones in the ASAS survey. In the case of the other two stars, V397 Gem and ASAS J075127-4136.3, we could not decide conclusively, as they are outliers in the period-Fourier-coefficient space from the loci of both classes, but their photometric metallicities also favour the RRc classification.