{"paper":{"title":"Photometric metallicity of Galactic RR Lyrae stars in the Gaia DR3 era","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"A new linear relation from Gaia G-band data estimates RR Lyrae metallicities with zero bias and 0.26 dex scatter using period and Fourier phase.","cross_cats":["astro-ph.GA"],"primary_cat":"astro-ph.SR","authors_text":"Harinder P. Singh, Mahiguhappriyaprakash, Nitesh Kumar, Susmita Das","submitted_at":"2026-05-13T17:38:38Z","abstract_excerpt":"We present a new, calibrated $G$-band relationship between pulsation period $P$, Fourier parameter $\\phi_{31}$, and metallicity [Fe/H] for galactic RR Lyrae stars from the Gaia survey. A set of 72 fundamental mode RR Lyrae stars were identified for deriving the relation in the $G$-band, after visual examination of their light curves. Unlike recent large-scale calibrations, our relation prioritizes calibration purity by anchoring exclusively to a homogeneously analyzed sample of high-resolution spectroscopic metallicities from the literature. Our best fit relation is $\\text{[Fe/H]} = (-6.93 \\pm"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Our best fit relation is [Fe/H] = (-6.93 ± 0.58) - (6.04 ± 0.37)P + (1.65 ± 0.11)φ31. ... achieving a negligible bias of 0.00 dex and an empirical RMS scatter of 0.26 dex.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The 72 fundamental-mode RR Lyrae stars selected after visual light-curve inspection form a representative sample whose spectroscopic metallicities can serve as unbiased ground truth for the full Galactic population across periods and metallicities.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"New G-band relation [Fe/H] = -6.93 - 6.04P + 1.65 φ31 calibrated on 72 RR Lyrae stars with spectroscopic anchors, yielding 0.00 dex bias and 0.26 dex RMS scatter.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"A new linear relation from Gaia G-band data estimates RR Lyrae metallicities with zero bias and 0.26 dex scatter using period and Fourier phase.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"3438fab058f42794b0c7e3dc76df56daecff6392c36253ba9af08d9048d4d103"},"source":{"id":"2605.13811","kind":"arxiv","version":2},"verdict":{"id":"725c90bd-0b43-4beb-89ee-bd25f95fc0d0","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-15T05:41:21.375518Z","strongest_claim":"Our best fit relation is [Fe/H] = (-6.93 ± 0.58) - (6.04 ± 0.37)P + (1.65 ± 0.11)φ31. ... achieving a negligible bias of 0.00 dex and an empirical RMS scatter of 0.26 dex.","one_line_summary":"New G-band relation [Fe/H] = -6.93 - 6.04P + 1.65 φ31 calibrated on 72 RR Lyrae stars with spectroscopic anchors, yielding 0.00 dex bias and 0.26 dex RMS scatter.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The 72 fundamental-mode RR Lyrae stars selected after visual light-curve inspection form a representative sample whose spectroscopic metallicities can serve as unbiased ground truth for the full Galactic population across periods and metallicities.","pith_extraction_headline":"A new linear relation from Gaia G-band data estimates RR Lyrae metallicities with zero bias and 0.26 dex scatter using period and Fourier phase."},"references":{"count":48,"sample":[{"doi":"10.1086/422916","year":null,"title":"The RR Lyrae Period-Luminosity Relation. I. Theoretical Calibration","work_id":"8357c08b-edaa-41f8-9ed2-95ea087328b6","ref_index":1,"cited_arxiv_id":"astro-ph/0406067","is_internal_anchor":true},{"doi":"10.1046/j.1365-8711.2001.04655.x","year":2001,"title":"Theoretical insights into the RR Lyrae K-band Period-Luminosity relation","work_id":"aceec4b5-15fb-49ee-ac88-05afafb74dc4","ref_index":2,"cited_arxiv_id":"astro-ph/0105481","is_internal_anchor":true},{"doi":"10.1093/mnras/216.4.873","year":null,"title":"VJHK observations of the RR Lyrae star VY Serpentis","work_id":"e5a1b7ba-7027-439d-a6b0-f08dd64328e2","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1111/j.1365-2966.2006.10962.x","year":2006,"title":"The RR Lyrae Period - K Luminosity relation for Globular Clusters: an observational approach","work_id":"40f3358c-02cd-4a3f-9749-36c816602bfe","ref_index":4,"cited_arxiv_id":"astro-ph/0608397","is_internal_anchor":true},{"doi":"10.1088/0004-637x/799/2/165","year":null,"title":"On the distance of the globular cluster M4 (NGC 6121) using RR Lyrae stars: I. optical and near-infrared Period-Luminosity and Period-Wesenheit relations","work_id":"0db998a1-1747-42aa-87eb-a58597c79c2e","ref_index":5,"cited_arxiv_id":"1411.6826","is_internal_anchor":true}],"resolved_work":48,"snapshot_sha256":"a30766cd7f436970560e8eb6266757e328a123ac2e2176c4395c3a5c1dbe765c","internal_anchors":16},"formal_canon":{"evidence_count":2,"snapshot_sha256":"2979bd3b375627a4d2b9452a106b4764b24aeb0bb4c8f3d78f5e9dc4e603d438"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}