| Issue |
A&A
Volume 707, March 2026
|
|
|---|---|---|
| Article Number | A275 | |
| Number of page(s) | 9 | |
| Section | Catalogs and data | |
| DOI | https://doi.org/10.1051/0004-6361/202558188 | |
| Published online | 19 March 2026 | |
A rotation-based census of blue lurker candidates in open clusters
1
Astronomical Institute, Faculty of Mathematics and Physics, Charles University,
V Holesovickách 2,
180 00
Praha 8,
Czech Republic
2
Institute of Astronomy, National Central University,
300 Zhongda Road,
Zhongli
32001
Taoyuan,
Taiwan
3
Dipartimento di Fisica e Astronomia, Università di Firenze,
Via G. Sansone 1,
50019
Sesto Fiorentino,
FI,
Italy
4
INAF – Osservatorio Astrofisico di Arcetri,
Largo E. Fermi 5,
50125
Firenze,
Italy
★ Corresponding authors: This email address is being protected from spambots. You need JavaScript enabled to view it.
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Received:
21
November
2025
Accepted:
28
January
2026
Abstract
Aims. We have compiled a list of blue lurker (BL) candidates in open clusters using the available rotation catalogs. Blue lurkers are rejuvenated main-sequence stars hidden among normal main-sequence stars on color-magnitude diagrams of star clusters. In comparison to BLs, blue straggler stars, which formed via similar mass transfers or mergers, occupy a distinct space in color-magnitude diagrams.
Methods. Blue lurkers can be identified by their unusually faster rotation compared to similar mass stars, which is a signature of recent accretion, or by the presence of a companion (e.g., an extremely low mass white dwarf), which can only be formed by mass donation. We searched for fast-rotating stars on the main sequence of open clusters using Kepler, TESS, and spectroscopic rotation indicators, such as rotation periods and v sin i measurements.
Results. We identified 97 new BL candidates across 35 open clusters, almost tripling the previously known sample of 36. Based on the estimated completeness of ≈3%, thousands of BLs are likely hidden within the cluster population. Detailed spectroscopic and time series analyses will be essential to confirming their mass-transfer histories.
Key words: methods: observational / catalogs / binaries: general / blue stragglers / stars: rotation / open clusters and associations: general
© 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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