Spatially resolved LMC star formation history – I. Outside in evolution of the outer LMC disc
Bibliographic record
Abstract
We study the evolution of three fields in the outer Large Magellanic Cloud (LMC) disc (Rgc = 3.5–6.2 kpc). Their star formation history indicates a stellar population gradient such that younger stellar populations are more centrally concentrated. We identify two main star-forming epochs, separated by a period of lower activity between ≃7 and ≃4 Gyr ago. Their relative importance varies from a similar amount of stars formed in the two epochs in the innermost field to only 40 per cent of the stars formed in the more recent epoch in the outermost field. The young star-forming epoch continues to the present time in the innermost field, but lasted only till ≃0.8 and 1.3 Gyr ago at Rgc = 5| $_{.}^{\circ}$|5 and 7| $_{.}^{\circ}$|1, respectively. This gradient is correlated with the measured H i column density and implies an outside-in quenching of the star formation, possibly related to a variation of the size of the H i disc. This could either result from gas depletion due to star formation or ram-pressure stripping, or from to the compression of the gas disc as ram pressure from the Milky Way halo acted on the LMC interstellar medium. The latter two situations may have occurred when the LMC first approached the Milky Way.
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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 | 0.001 |
| 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".