{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"412e2b23f768167c83a43d22c5795bd035de65abbb830a4d1d8e9cb097d4f76d","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["9f03e1f2ddf9f19687c7edd1effce2a7ca04aeddba0cfeccc945111b9eb95c85","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"242a06b4195f52cd59d89a63a513306fbc1421f9c16c257caf2d74b7693e3bd1","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":"2","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 $\\sim 10^{4}\\,\\mathrm{yr}$, 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":"9f03e1f2ddf9f19687c7edd1effce2a7ca04aeddba0cfeccc945111b9eb95c85","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":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"38507440a4d4d2a3e0e5f10ceb4509447d35e13cb2c0608fbc701838fcf71061","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"9bbeb4d605bbb527e7cde1daf3c917b71b3747f50c1f3364650471c0c2bbda3d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"IFG7KFaq53YUUKtSl2Ffo-GVyPa_rdEgBtzeSjugZcdRqrUI7R_RMND2cgOLJtGmBxOknyN63t5mWlBf-dbiBQ"},"schema":"pubphys.envelope/1"},"record_hash":"38507440a4d4d2a3e0e5f10ceb4509447d35e13cb2c0608fbc701838fcf71061","leaf_index":2434}