The distance from the Sun to the centre and the shape of the old bulge in the Galaxy: 16 221 OGLE RR Lyrae stars
Bibliographic record
Abstract
ABSTRACT A statistical method is used to determine both the Sun’s distance r0 from the Galactic Centre and the 3D structure of the old stellar population of the Galactic bulge. The space distribution of 16 221 high latitude type-RRab RR Lyrae stars from the optical OGLE survey located towards the bulge is explored. An estimate by using RR Lyraes leads to a mean r0 = 8.28 ± 0.14 kpc within the effective bulge radius of rbulge = 2–3 kpc. The distribution of RR Lyraes within rbulge has the shape of an ellipsoid slightly elongated almost towards the Sun with a major axis of its symmetry a and two minor axes b and c of about the same length. The axial ratio is a: b: c ≈ 1: 0.7: 0.7. These age-old, metal-poor, and kinematically hot stars do not trace a strong bar-like structure in the direction of the bulge at distances >1 kpc from the Galactic Centre, as b/a ∼ 1.
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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 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".