MHD simulations of the formation and propagation of protostellar jets to observational length-scales
Bibliographic record
Abstract
We present 2.5D global, ideal magnetohydrodynamic (MHD) simulations of magnetically and rotationally driven protostellar jets from Keplerian accretion discs, wherein only the initial magnetic field strength at the inner radius of the disc, Bi, is varied. Using the AMR-MHD code AZEuS, we self-consistently follow the jet evolution into the observational regime (|$\gt 10^3\, \mathrm{au}$|) with a spatial dynamic range of ∼6.5 × 105. The simulations reveal a three-component outflow: (1) A hot, dense, super-fast, and highly magnetized ‘jet core’; (2) a cold, rarefied, trans-fast, and highly magnetized ‘sheath’ surrounding the jet core and extending to a tangential discontinuity; and (3) a warm, dense, trans-slow, and weakly magnetized shocked ambient medium entrained by the advancing bow shock. The simulations reveal power-law relationships between Bi and the jet advance speed, |$v$|jet, the average jet rotation speed, 〈|$v$|φ〉, as well as fluxes of mass, momentum, and kinetic energy. Quantities that do not depend on Bi include the plasma-β of the transported material that, in all cases, seems to asymptote to order unity. Jets are launched by a combination of the ‘magnetic tower’ and ‘bead-on-a-wire’ mechanisms, with the former accounting for most of the jet acceleration – even for strong fields – and continuing well beyond the fast magnetosonic point. At no time does the leading bow shock leave the domain and, as such, these simulations generate large-scale jets that reproduce many of the observed properties of protostellar jets including their characteristic speeds and transported fluxes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".