{"paper":{"title":"SN 2017ati: A luminous type IIb explosion from a massive progenitor","license":"http://creativecommons.org/licenses/by/4.0/","headline":"SN 2017ati's light curve is powered by both magnetar spin-down and radioactive nickel decay, implying a progenitor of at least 17 solar masses.","cross_cats":["astro-ph.GA","astro-ph.HE"],"primary_cat":"astro-ph.SR","authors_text":"A. Pastorello, A. Reguitti, A. Somero, E. Cappellaro, E. Kankare, J.-J. Zhang, J.-W. Zhao, L. Tomasella, M. D. Stritzinger, M. Fraser, N. Elias-Rosa, P. Lundqvist, Q.-L. Fang, S. Benetti, S. Mattila, S.-P. Pei, T. Kangas, T. M. Reynolds, Y.-J. Yang, Y. Pan, Y.-Z. Cai, Z.-H. Peng, Z. Kostrzewa-Rutkowska, Z.-Y. Wang","submitted_at":"2026-02-04T12:02:02Z","abstract_excerpt":"We present optical photometric and spectroscopic observations of the Type~IIb supernova (SN)~2017ati. It reached the maximum light at about 27~d after the explosion and the light curve shows a broad, luminous peak with an absolute $r$-band magnitude of $M_{r} = -18.48 \\pm 0.16$~mag. At about 50~d after maximum light, SN~2017ati exhibits a decline rate close to that expected from the $^{56}$Co $\\rightarrow$ $^{56}$Fe radioactive decay, at 0.98 mag per 100 days, as usually observed in SNe IIb. However, it remains systematically brighter at late times by about 1--2~mag, exceeding the usual upper "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"its luminosity evolution is best explained by a combination of neutron star spin-down energy and radioactive nickel deposition... the combination of a [CaII]/[OI] flux ratio of ~0.5 with nebular spectral model comparisons favours a progenitor zero-age main-sequence mass of ≥17 M⊙","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the excess late-time luminosity is produced by magnetar spin-down rather than other mechanisms such as circumstellar interaction, and that the nebular line luminosities translate directly to oxygen mass without large systematic uncertainties in the spectral models.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"SN 2017ati's light curve requires both 0.21 solar masses of nickel and magnetar spin-down energy to fit, with nebular spectra implying a progenitor zero-age main-sequence mass of at least 17 solar masses.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"SN 2017ati's light curve is powered by both magnetar spin-down and radioactive nickel decay, implying a progenitor of at least 17 solar masses.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"6788e26a6d37edd55329ee95979539db1ef324bde8d8600ef85f7818d7996395"},"source":{"id":"2602.04474","kind":"arxiv","version":2},"verdict":{"id":"604b4a31-78db-446b-baea-9187fd5af403","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-16T07:25:55.831769Z","strongest_claim":"its luminosity evolution is best explained by a combination of neutron star spin-down energy and radioactive nickel deposition... the combination of a [CaII]/[OI] flux ratio of ~0.5 with nebular spectral model comparisons favours a progenitor zero-age main-sequence mass of ≥17 M⊙","one_line_summary":"SN 2017ati's light curve requires both 0.21 solar masses of nickel and magnetar spin-down energy to fit, with nebular spectra implying a progenitor zero-age main-sequence mass of at least 17 solar masses.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the excess late-time luminosity is produced by magnetar spin-down rather than other mechanisms such as circumstellar interaction, and that the nebular line luminosities translate directly to oxygen mass without large systematic uncertainties in the spectral models.","pith_extraction_headline":"SN 2017ati's light curve is powered by both magnetar spin-down and radioactive nickel decay, implying a progenitor of at least 17 solar masses."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2602.04474/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":2,"snapshot_sha256":"858c826a9175b8ae4fe61013617e4b900ff41c66fbac462f2c6d165b7fb7e8cc"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}