{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"54415db0826e91be0650d87f3e29771ee2a25b315d800b304323dcd58d6b58ba","created":"2026-10-03T07:17:54Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"750c7aebb2865a91852479ccdad379d7cf4ec1537d69ef1b33c3c85760aee3ee","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.accretion-jet-launching.alpha-discrepancy","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"The magnetorotational instability (magnetic stirring of orbiting gas) explains how disks move angular momentum outward, but simulations give about ten times less transport than outbursts of real disks imply.","posed_since":"2007","precise":"Outburst decay times of fully ionized disks in dwarf novae and X-ray binaries imply Shakura-Sunyaev $\\alpha \\sim 0.1 \\text{ to } 0.4$, while MHD simulations of magnetorotational turbulence without net vertical magnetic flux give $\\alpha \\sim 0.01 \\text{ to } 0.03$. Determine which physics closes the gap: net vertical flux, convection, magnetized winds removing angular momentum, or spiral shocks. Answer: a mechanism with $\\alpha$ as a function of ionization state and net flux that reproduces outburst light curves.","problem_ref":null,"references":"","settled_by":"Global simulations with self-consistent thermodynamics reproducing measured dwarf-nova outburst decay times.","status_note":"","title":"Why do observed disks transport angular momentum faster than simulations?","topic_ref":"c6622c49671f85d956e06199b59037776536a6db727b79f3ac01839ce91af768"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"838b5ee0bf01750cfdf193ca87de330e9b7c683b839453df96b8fc9af9497974","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1a10fd7afe304280fdd3c08b91f543af3e255f037f66c4be785d70d1bec803d5","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"xStV84xrvmGQ4AE28A2NhF-uYI6gAiPoBkwxBJsguE3Ce233nZB4dy-xiEjOPFWjy8yLbuKahJXuZi4J9toeDg"},"schema":"pubphys.envelope/1"},"record_hash":"838b5ee0bf01750cfdf193ca87de330e9b7c683b839453df96b8fc9af9497974","leaf_index":478}