{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"168c631d2a232709f97d7c110b3220cd5bf2f6a38b1a664b08b71a5bc040b6e5","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"b6c45f4993d24edfc99c75e1f24ee301545484acb04e0773d93244bc733e3667","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.r-process-sites.actinide-boost","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"In old stars enhanced in r-process elements the medium-heavy elements follow the Sun's pattern closely, yet a sizable minority show extra thorium and uranium, hinting that the conditions or sites differ.","posed_since":"","precise":"In r-process-enhanced metal-poor stars ($[\\mathrm{Eu}/\\mathrm{Fe}]>+0.3$) the abundance pattern from Ba to Hf closely matches the scaled solar r-process, while $\\log(\\mathrm{Th}/\\mathrm{Eu})$ varies, with a sizable minority (estimates near one third) showing an actinide boost. Determine whether the variation reflects different electron-fraction ($Y_e$) distributions of merger dynamical ejecta versus disk winds, different sites, or fission-physics uncertainties. Answer: a site and $Y_e$ distribution reproducing the observed $\\mathrm{Th}/\\mathrm{Eu}$ distribution and its correlation with other abundance ratios.","problem_ref":null,"references":"","settled_by":"Th, U and Eu abundances for a large sample of r-process-enhanced stars compared with yields from merger and collapsar simulations with consistent nuclear inputs.","status_note":"","title":"Why do some r-process-enhanced stars have extra thorium and uranium?","topic_ref":"629fb53d8771f28ff08120cbd19ad49c2c6fdc9fd60798b0f0a9704b24fc3033"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"c78baf8775f8154a8392702113b47ef0348ea72671facaf11abc5812740f02e7","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"ce6f2d69ea2910971d8a3eb66b093918a9b6b0f7e8cf6b319f7875834725af96","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"Q7WjMDvxj3tUOUs-fvE8G4rnwOa3qdqx2GMhijVpX-xMB3aMSvZLYeYsCwBwSdC6lsPd5Hua2ftVjX_HOI7RAw"},"schema":"pubphys.envelope/1"},"record_hash":"c78baf8775f8154a8392702113b47ef0348ea72671facaf11abc5812740f02e7","leaf_index":590}