Angular momentum transport via gravitational instability in the Elias 2–27 disc
Bibliographic record
Abstract
Gravitational instability is thought to be one of the main drivers of angular momentum transport in young protoplanetary discs. The disc around Elias 2−27 offers a unique example of gravitational instability at work. It is young and massive, displaying two prominent spiral arms in dust continuum emission and global non-axisymmetric kinematic signatures in molecular line data. In this work, we used archival ALMA observations of 13 CO line emission to measure the efficiency of angular momentum transport in the Elias 2−27 system through the kinematic signatures generated by gravitational instability, known as “GI wiggles”. Assuming the angular momentum is transported by the observed spiral structure and leveraging previously-derived dynamical disc mass measurements, the amount of angular momentum transport we found corresponds to an α -viscosity of α = 0.038 ± 0.018. This value implies an accretion rate onto the central star of log 10 Ṁ ⋆ = −6.99 ± 0.17 M ⊙ yr −1 , which reproduces the one observed value of log 10 Ṁ ⋆,obs = −7.2 ± 0.5 M ⊙ yr −1 very well. The excellent agreement we have found serves as further proof that gravitational instability is the main driver of angular momentum transport acting in this system.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".