Evidence for episodic and patchy mass ejection in the circumstellar envelope of AGB star R Leonis
Bibliographic record
Abstract
ABSTRACT The morpho-kinematics of the circumstellar envelope of oxygen-rich AGB star R Leonis is probed using Atacama Large Millimeter/submillimeter Array observations of the emission of molecular lines, including in particular CO(2–1) and 29SiO(5–4). Evidence is found for an episode of enhanced mass-loss, a few centuries ago, that produced a broad expanding shell of mean radius ∼6 arcsec and mean radial expansion velocity ∼5.5 km s−1. Detailed scrutiny of its structure, as displayed by the emission of the CO(2–1) line, reveals strong inhomogeneity and patchy morphology. Evidence is also found, in particular from the morpho-kinematics of the emission of SiO, SO, and SO2 lines probing the close neighbourhood of the star, for distinct gas outflows covering broad solid angles in the south-eastern, south-western, and north-western quadrants, suggesting significant contribution of the convective cell granulation in defining the pattern of mass ejection. A study of relative molecular abundances in these outflows suggests that a local thermal equilibrium description applies approximately beyond ∼10 stellar radii from the centre of the star but not at the smaller angular separations where the SO and SO2 molecules are found to be confined. Near the stellar disc, masers of the vibrationally excited SiO lines are found to probe north-western parts of a layer of hot gas, consistent with the earlier observation of an asymmetric expanding shell within 1–2 stellar radii from the centre of the star. Globally, a picture dominated by episodic and patchy mass ejections is found to prevail.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".