{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"616cc3a9d7d15e5f121c99c7f61c201c0fd9c03c64612b33a7c3ee28d8d190ff","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"7faf542d0154b8ac80ef21abb6c7369f20cd54bd24b7935ba7163b7a50a12d1a","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"astro.protoplanetary-disks.accretion-driver","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"Gas in a disk can only fall onto the star if it loses its spin, either by passing it outward through turbulent stirring or by carrying it away in a magnetized wind (gas flung off the disk surface along magnetic field lines). Measurements suggest the disks are too calm for turbulence to do the job, but this is not settled.","posed_since":"","precise":"Classical T Tauri disks accrete at $\\mathrm{mdot} \\sim 10^{-9}-10^{-7}\\ M_{\\mathrm{sun}}/\\mathrm{yr}$; a turbulent-viscosity model needs $\\alpha \\sim 10^{-3}-10^{-2}$, while non-ideal MHD (low ionization, Ohmic, ambipolar and Hall effects) suppresses the magnetorotational instability over much of $1-30\\ \\mathrm{AU}$. Determine the fraction of the angular-momentum flux carried by magnetized disk winds versus radial turbulent transport as a function of radius, using nonthermal molecular line widths, dust vertical settling, and measured wind mass-loss rates. The answer is the radial profile of the wind-to-turbulent torque ratio, or a demonstration that one channel dominates at $1-100\\ \\mathrm{AU}$ in typical disks.","problem_ref":null,"references":"","settled_by":"ALMA turbulence and settling measurements combined with spatially resolved wind tracers (JWST molecular hydrogen and forbidden-line imaging) for the same disks, compared with the measured stellar accretion rates.","status_note":"ALMA line-width and dust-settling studies of 2015-2020 find $\\alpha$ below about $10^{-3}$ in most disks examined, which favors wind-driven accretion, but turbulence with $\\alpha$ of order 0.1 was reported in DM Tau (Flaherty et al. 2020).","title":"Do magnetized winds or turbulence drive accretion in protoplanetary disks?","topic_ref":"8ff53117308df146f6983fc1ee6578221825c827c392f4ce6c47231d3772e7ef"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"50dff91e63d27f27ddd45e5f78b0a855baed84121d3d44c05bf260b22f32da25","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"ffaea9b1eab17aee24aeac6e3ede4359b8a1288ed8a6f7b5af9c274249c00222","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"cQFt1nx2vhHq5OTVVzCHsHn39ZzQUUxcOJ0FV7WNXe6u1RMS50mvGvnMVjW3q7JO0abfa82mgrsfHNj6epAeDQ"},"schema":"pubphys.envelope/1"},"record_hash":"50dff91e63d27f27ddd45e5f78b0a855baed84121d3d44c05bf260b22f32da25","leaf_index":579}