| Issue |
A&A
Volume 707, March 2026
|
|
|---|---|---|
| Article Number | A58 | |
| Number of page(s) | 16 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361/202557724 | |
| Published online | 26 February 2026 | |
RR Lyrae stars with variable mean magnitudes
1
Nicolaus Copernicus Astronomica Center Bartycka 18 00-629 Warsaw, Poland
2
Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences Konkoly-Thege Miklós út 15-17 Budapest H-1121, Hungary
3
Instituto de Astrofísica, Pontificia Universidad Católica de Chile Av. Vicuña Mackenna 4860 Macul 7820436 Santiago, Chile
4
Millenium Institute of Astrophysics Nuncio Monseñor Sotero Sanz 100 Providencia Santiago, Chile
5
Departmento de Astronomía, Universidad de Concepción Casilla 160-C Concepción, Chile
6
Astronomical Observatory, University of Warsaw Al. Ujazdowskie 4 Warsaw 00-478, Poland
7
Korea Astronomy and Space Science Institute Daejeon 34055, Republic of Korea
★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
16
October
2025
Accepted:
14
December
2025
Abstract
Context. A number of RR Lyrae stars exhibit variable mean magnitudes in the OGLE survey light curves of the Galactic bulge. Hitherto, this phenomenon has not been studied, as it was generally assumed to be related to photometric issues.
Aims. We investigate whether the mean magnitude variability of RR Lyrae variables is due to genuine astrophysical phenomena.
Methods. We used the extended, and in many cases overlapping, light curves from multiple microlensing surveys to study RR Lyrae stars with apparent mean-magnitude variations. A modified Fourier-series based fitting method is introduced to analyze the light curves showing mean-magnitude variations. Data from infrared surveys were also used to construct spectral energy distributions (SEDs).
Results. Presented here are 72 stars where the mean-magnitude variations are most probably of genuine astrophysical origin, rather than the result of photometric problems. The ratio of variation between the V and I bands is compatible with variable extinction by dust in most cases, but no infrared excess is detected in the SEDs. The occurrence rate of the phenomenon, after correcting for selection effects, is ∼0.9% among RR Lyrae variables in the OGLE bulge fields.
Key words: circumstellar matter / stars: variables: RR Lyrae / dust / extinction / Galaxy: bulge
© The Authors 2026
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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