The Milky Way's external disc constrained by 2MASS star counts
Bibliographic record
Abstract
Context. Thanks to recent large-scale surveys in the near infrared, such as 2MASS, the galactic plane that most suffers from extinction is revealed so its overall structure can be studied.Aims. This work aims at constraining the structure of the Milky Way external disc as seen in 2MASS data, and in particular the warp.Methods. We use the Two Micron All Sky Survey (hereafter 2MASS) along with the Stellar Population Synthesis Model of the Galaxy, developed in Besançon, to constrain the external disc parameters, such as its scale length, its cutoff radius, and the slope of the warp. To properly interpret the observations, the simulated stars are reddened using a 3D extinction map. The shape of the stellar warp is then compared with previous results and with similar structures in gas and dust. Results. We find new constraints on the stellar disc, which is shown to be asymmetrical, similar to observations of HI. The positive longitude side is found to be easily modelled with S-shaped warp but with a significantly smaller slope than the one seen in the HI warp. At negative longitudes, the disc presents peculiarities that are not reproduced well by any simple model. Finally, comparing with the warp seen in the dust, it seems to follow an intermediate slope between the gas and the stars.
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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 | 0.001 |
| 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 | 0.001 |
| 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".