The importance of photosphere cooling in simulations of gravitational instability in the inner regions of protostellar discs
Bibliographic record
Abstract
The fragmentation of protostellar discs via gravitational instability (GI) has been proposed as a mechanism for forming giant planets. We present methods and tests for a new implementation of radiative transfer in the Gasoline TreeSPH code with which we investigate the viability of this mechanism in the inner tens of au of discs. Accurate photosphere boundary treatments are of fundamental importance to the outcome of GI. We demonstrate that previous photosphere treatments using edge-particles overestimate the cooling rate, and present a new treatment that can accurately determine photosphere cooling, as demonstrated by its ability to satisfy the relaxation test of Boley et al. (2007b). This is the first time this test has been carried out with smoothed particle hydrodynamics. We carry out simulations of protostellar discs that are unstable in the inner tens of au and find that they do not fragment because they do not cool fast enough. One of these cases has been previously found to undergo fragmentation. The fact that we do not observe fragmentation in this simulation emphasizes the use of accurate photosphere boundary treatments and the difficulty of forming giant planets in the inner disc (inside of 40 au) via the GI mechanism.
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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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".