{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"56a2f4afa8b3a21c5067e0a34698866226cf7c8bdb9fcd0b9dcb9e040da62ebe","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["018e97ee2e034ceb19fbb4883a0ea7bb13d184c9bcbf70a58a5f3554895c3e98","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"273bf4ff2e1f30acdea91367e7bec1cc904d35bdc709457bddf4ac68886b3518","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.star-formation-imf.low-efficiency","kind":"phenomenon","literature_status":"open","n":"2","parents":[],"plain":"If gas clouds simply collapsed under their own weight, galaxies would form stars about a hundred times faster than they do. Turbulence, magnetic fields and the push of newborn stars all slow it down, but which one sets the value is unknown.","posed_since":"1974","precise":"Molecular clouds convert gas into stars at efficiency per free-fall time eps_ff = SFR t_ff / M_gas ~ 0.01, with integrated cloud efficiencies of $\\sim 1-10\\%$ before dispersal. Explain the value and its scatter as a function of cloud surface density and virial parameter, separating the roles of supersonic turbulence, magnetic support and stellar feedback (photoionization, winds, radiation pressure, jets, supernovae).","problem_ref":"018e97ee2e034ceb19fbb4883a0ea7bb13d184c9bcbf70a58a5f3554895c3e98","references":"","settled_by":"Simulations with all feedback channels that reproduce the measured eps_ff distribution across cloud populations, plus observations that measure eps_ff and its dependence on surface density in many galaxies.","status_note":"","title":"Why does gas form stars at only one percent per free-fall time?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"229e5ed631c9b61d578c224be1bf76308b7595dab8df8f8ed41ecfc9c1f4bb63","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c55be1c4615ffee75a15fdf346423f6fb173edc0c9dd2a9ee64e7d29e416bf96","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"LHKyKXR6yn5Bqmmyjbidw7i7t5DTCh3A5kWXhBb6H6Ukz7VusqTmOAwfFqCWP78U8pHiLqZzDVHuotT5OzXeBw"},"schema":"pubphys.envelope/1"},"record_hash":"229e5ed631c9b61d578c224be1bf76308b7595dab8df8f8ed41ecfc9c1f4bb63","leaf_index":2438}