{"paper":{"title":"Photometric Identification of Unresolved Binary Stars in Nearby Open Star Clusters","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Empirical isochrones revise binary fraction estimates downward in open clusters.","cross_cats":["astro-ph.SR"],"primary_cat":"astro-ph.GA","authors_text":"Anastasiia Plotnikova, Anton F. Seleznev, Giovanni Carraro, Varvara O. Mikhnevich","submitted_at":"2026-04-22T16:07:28Z","abstract_excerpt":"This paper introduces a new method to search for unresolved binary stars in open star clusters. The work aims at improving the approach introduced previously, which employs the (H-W2)-W1 versus W2-(BP-K) photometric diagram. This diagram, in tandem with the Gaia Color Magnitude Diagram (CMD) and using theoretical isochrones as reference sequences, is used to estimate the binary star fraction and the distribution of the component mass ratio $q$ in eight nearby open star clusters, including Pleiades, Alpha Per, and Praesepe, which we investigated in previous studies. In this study, to alleviate "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"We show that this is an effective approach to exploring a wider primary-mass interval, in particular for the region of low-mass sources. The binary fraction estimate lies in the range 0.16 - 0.36 and 0.21 - 0.44, depending on the adopted method, and show that in previous studies the binary fraction was overestimated.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the empirical isochrones constructed from the observed data accurately represent the sequence of single stars without contamination from unresolved binaries or other effects, and that the photometric separation in the (H-W2)-W1 versus W2-(BP-K) diagram reliably identifies binaries across the mass range.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Empirical isochrones in photometric diagrams enable identification of unresolved binaries in eight nearby open clusters, yielding binary fractions of 0.16-0.44 and mass ratio modes around 0.4-0.8.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Empirical isochrones revise binary fraction estimates downward in open clusters.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"6242308dc69d0a92a0a506ef034da71cd36507bfb2e8455e6b6073da2745f3a0"},"source":{"id":"2604.20722","kind":"arxiv","version":1},"verdict":{"id":"22a525a9-2b3f-4d06-88fd-9513e3ac925b","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-09T23:32:59.789230Z","strongest_claim":"We show that this is an effective approach to exploring a wider primary-mass interval, in particular for the region of low-mass sources. The binary fraction estimate lies in the range 0.16 - 0.36 and 0.21 - 0.44, depending on the adopted method, and show that in previous studies the binary fraction was overestimated.","one_line_summary":"Empirical isochrones in photometric diagrams enable identification of unresolved binaries in eight nearby open clusters, yielding binary fractions of 0.16-0.44 and mass ratio modes around 0.4-0.8.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the empirical isochrones constructed from the observed data accurately represent the sequence of single stars without contamination from unresolved binaries or other effects, and that the photometric separation in the (H-W2)-W1 versus W2-(BP-K) diagram reliably identifies binaries across the mass range.","pith_extraction_headline":"Empirical isochrones revise binary fraction estimates downward in open clusters."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2604.20722/integrity.json","findings":[],"available":true,"detectors_run":[{"name":"ai_meta_artifact","ran_at":"2026-05-21T14:33:36.044720Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_compliance","ran_at":"2026-05-20T01:38:39.628006Z","status":"completed","version":"1.0.0","findings_count":0}],"snapshot_sha256":"b452724d566e0847ddd764e9c10eb31525366143450c53c0cb2ba1e29d8cb752"},"references":{"count":70,"sample":[{"doi":"10.1093/mnras/stae2636","year":2025,"title":"S., & Albrow, M","work_id":"d147afaa-dd3b-476f-8289-74bcd91158dd","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.48550/arxiv.2504.06362","year":2025,"title":"Maia, F. 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J., et al. 2013, A&A, 558, A33, doi: 10.1051/0004-6361/201322068 Astropy Col","work_id":"a755cfd0-c465-46f9-846d-24c2c052a40f","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1111/j.1365-2966.2011.19955.x","year":2012,"title":"A., et al., 2011, @doi [ ] 10.1111/j.1365-2966.2011.18706.x , http://adsabs.harvard.edu/abs/2011MNRAS.417.1621D 417","work_id":"d145e33f-f528-4886-b1e5-0963b1b5c030","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1093/mnras/245.1.15","year":1990,"title":"1990, MNRAS, 245, 15, doi: 10.1093/mnras/245.1.15","work_id":"ab495fe5-a01e-4ac8-a1c6-3ce917e914e0","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":70,"snapshot_sha256":"683a8e1bcae798f62ecca3fff804bec9e96821c787adcc0fea4d462d8c5fcf3e","internal_anchors":1},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}