{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"5c6a077e8ee5b50519f1dcefed68e8443621f069c1413d0aaec632b72637e1a5","created":"2026-10-03T07:17:54Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"92e9f264df87ca6df1af4d8ef22ad3b22847b2ef604de33cac3819a821e80bda","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.core-collapse-supernovae.precursor-mass-loss","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"Many supernovae explode into thick gas that the star shed only years to decades before dying, far more than normal stellar winds can explain.","posed_since":"","precise":"Early spectra with narrow, short-lived emission lines (flash ionization) show dense circumstellar material within $\\sim 1\\mathrm{e}15\\,\\mathrm{cm}$ in a large fraction of Type II supernovae, implying mass-loss rates ~1e-4 to 1e-2 M_sun/yr in the last years, far above steady red supergiant winds of ~1e-6 M_sun/yr. Identify the mechanism (wave energy transport from core convection in the last burning stages, binary interaction, pulsation-driven winds) and whether it also produces observed pre-explosion outbursts. Answer: a mechanism predicting circumstellar mass and extent versus progenitor mass and evolutionary stage.","problem_ref":null,"references":"","settled_by":"Pre-explosion monitoring of many nearby supernova progenitors combined with early spectra, compared with predicted outburst timing and circumstellar masses.","status_note":"2023: SN 2023ixf in M101, the nearest Type II supernova in a decade, showed dense, confined circumstellar material.","title":"What drives heavy mass loss in the final years before collapse?","topic_ref":"6ce88d543f229da8760987ece77815cb22f0cdd520afe70f0c6fe63515181dfc"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"a93dbffe220d30a4b58ec3f954224252cf872d031a35eb4ca93b771da0e09cb0","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"a417db690678c543ce92ab8e06de1be7660cacf170973b646f56edf64905ab21","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"thVaTv-81XH3zkBvYrwUQJqcwMUBYdqAraSSnF8ju23ON9g106k5mI19AqNkB5C0Yc1b8qc46-uKb_wQSYrkBw"},"schema":"pubphys.envelope/1"},"record_hash":"a93dbffe220d30a4b58ec3f954224252cf872d031a35eb4ca93b771da0e09cb0","leaf_index":504}