{"paper":{"title":"Quantitative Spectroscopic Diagnostics for FU Orionis-Type Young Stellar Objects","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Near-infrared spectral features distinguish FU Orionis outburst disks from normal stars.","cross_cats":[],"primary_cat":"astro-ph.SR","authors_text":"Adolfo S. Carvalho, Evan R. Portnoi, Lynne A. Hillenbrand","submitted_at":"2026-05-12T22:21:40Z","abstract_excerpt":"We present near-infrared spectroscopic diagnostics that can be used to identify FU Orionis stars (FUOrs). FUOrs are young stellar objects (YSOs) that are currently in a state of extreme outburst, caused by enhanced mass {inflow} from their accretion disks. The disks give FUOrs a distinct multi-temperature optical and infrared spectrum. Considering both the predicted spectrum from a disk atmosphere model, and existing spectral diagnostics from the literature, we identify key atomic and molecular features for characterizing FUOrs. Some of the chosen features are proxies for temperature, others a"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"By considering the relative distributions of these samples in our defined spectral diagnostics, we propose a number of parameter spaces that can distinguish FUOr disks from normal stars.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the selected atomic and molecular features remain distinctive across the full range of FUOr viewing angles, disk inclinations, and evolutionary stages, and that the control sample adequately represents the contaminants expected in photometric candidate lists.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Quantitative near-IR diagnostics based on equivalent widths and band ratios distinguish FUOr disks from normal late-type stars using spectra of 28 known objects.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Near-infrared spectral features distinguish FU Orionis outburst disks from normal stars.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"7d2215169c71090e7c3cf07e087c50f57c8a1f85f417b3742ce89e9d3774da1d"},"source":{"id":"2605.12795","kind":"arxiv","version":1},"verdict":{"id":"b7439df9-5b98-4810-a512-9587d11e2e6d","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-14T19:26:03.451792Z","strongest_claim":"By considering the relative distributions of these samples in our defined spectral diagnostics, we propose a number of parameter spaces that can distinguish FUOr disks from normal stars.","one_line_summary":"Quantitative near-IR diagnostics based on equivalent widths and band ratios distinguish FUOr disks from normal late-type stars using spectra of 28 known objects.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the selected atomic and molecular features remain distinctive across the full range of FUOr viewing angles, disk inclinations, and evolutionary stages, and that the control sample adequately represents the contaminants expected in photometric candidate lists.","pith_extraction_headline":"Near-infrared spectral features distinguish FU Orionis outburst disks from normal stars."},"references":{"count":43,"sample":[{"doi":"","year":2024,"title":"Journal of Open Source Software , year = 2024, doi =","work_id":"872c5748-eca5-40e6-a3c9-7884cfa8d0e6","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2009,"title":"FUSE Measurements of Far-Ultraviolet Extinction. III. The Dependence of R(V) and Discrete Feature Limits From 75 Galactic Sightlines. , year = 2009, doi =","work_id":"7b8abb74-6259-48bd-be82-ea6631f04ebe","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2018,"title":", year = 2018, doi =","work_id":"a0f70b18-b1c5-4bb9-b4a3-9b221a6e7486","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2010,"title":", year = 2010, doi =","work_id":"93adf5d2-ef52-4503-b629-ce405c87025c","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2021,"title":", year = 2021, doi =","work_id":"b3731336-88f8-45e0-96de-510328a05f70","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":43,"snapshot_sha256":"251c75a59b81e18ce09b64035c1792fc3620f513e79770997d81dca68e8c1011","internal_anchors":3},"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"}