{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"09fa4bcf8250170b6ae0b3376b1a39c5c1aaf144c69d73022984d686c4db45ea","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"73c7524f6c5cf97a8f0e1f6a61c204b5fbaf7863cf967bbe487394d84d5b53c5","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.solar-interior-cycle.grand-minima","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"From about 1645 to 1715 sunspots nearly vanished, and radioactive isotopes in tree rings and ice show many such quiet spells; whether they come from random noise in the dynamo or from a deterministic switch is unknown.","posed_since":"1976","precise":"Cosmogenic isotope records (C-14, Be-10) show a few tens of grand minima over the last $\\sim 1e4\\,\\mathrm{yr}$, occupying of order one sixth of the time. Determine whether entry and exit arise from stochastic fluctuations in the Babcock-Leighton poloidal source (scatter of active-region tilt angles, rare anomalous active regions), from nonlinear deterministic dynamo dynamics, or from changes in meridional flow, and whether the waiting-time distribution is exponential. Answer: a model reproducing the frequency and duration distribution of grand minima and the hemispheric asymmetry of the Maunder Minimum.","problem_ref":null,"references":"","settled_by":"Dynamo models calibrated on observed tilt-angle statistics whose simulated grand-minimum statistics agree with the isotope record.","status_note":"","title":"What causes grand minima such as the Maunder Minimum?","topic_ref":"198e5d8c650c549166ecfcbee7e1125fa6cc28a6930904820f971b95ad0953ee"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"9f03e1f2ddf9f19687c7edd1effce2a7ca04aeddba0cfeccc945111b9eb95c85","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"a304e821227d3f99d7c070fe8f4114002f4095203783f6fe0763200ae585c502","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"YgwuSxIPr5SuhBfIcUKZM1MMNVb8cwRDn_YvcFyny2vBF4ZaVWWivwhNFgC47FrnbNyL62FQjNmMuZzolU0YDQ"},"schema":"pubphys.envelope/1"},"record_hash":"9f03e1f2ddf9f19687c7edd1effce2a7ca04aeddba0cfeccc945111b9eb95c85","leaf_index":621}