Evidence for reformation of the Uranian bow shock: Hybrid simulations and comparisons with Voyager data
Bibliographic record
Abstract
The cyclic reformation of shock structures is still a major unresolved issue for collisionless shock physics. We investigate the Voyager 2 spacecraft's encounter with the Uranian bow shock and present the first detailed quantitative evidence that the bow shock was reforming. This evidence is based on finding very good agreement between Voyager observations of the Uranian bow shock and results from a standard 1-D hybrid simulation code run with similar plasma parameters. Specifically, the multiple large localized magnetic field enhancements B/B 0 16 observed downstream by Voyager 2, where B 0 = 0.19 nT is the upstream magnetic field, are quantitatively consistent with the reforming shock found in the simulation. Moreover, the variability and large enhancement factors for B and the number density, as well as the variations of the plasma velocity, and ion temperature over an almost 2-h period including and after the shock crossing, are consistent with Voyager being very close to the reforming bow shock and with the Uranian bow shock receding planetward with the spacecraft. Additional simulations show the magnetic overshoot factor to increase approximately linearly with Alfvn Mach number and to be robust against changes in magnetic field orientation (from quasi-parallel to quasi-perpendicular). These large overshoots may be important in applications involving particle acceleration and type II solar radio bursts. In addition, we estimate the effective numerical resistivity of our code by comparing simulations with varying applied resistivity. The estimated numerical resistivity found is consistent with estimates inferred from observations of Earth's bow shock by
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".