Multi-color photometry in wide field of the Galactic globular cluster NGC 3201
Bibliographic record
Abstract
Aims. This paper aims at further studying one of the nearby Galactic globular clusters (GCs), NGC 3201. It is known to experience notable irregular variability of reddening across its face. By relying on our previous studies and findings and by developing them, we focus on the brighter sequences of the color-magnitude diagram (CMD) and on the cluster's characteristics.Methods. We carried out and analyzed new multi-color photometry of NGC 3201 in UBVI reaching below the turnoff point in all passbands in a fairly large cluster field, about . To achieve more reliable results and conclusions, we reduced the negative impact of the irregularly varying reddening and contamination by field stars.Results. With this aim we first estimated mean reddening in different zones of the studied cluster field and then took its variations into account, by reducing them to the same level. We estimated metallicity of NGC 3201 using a new metallicity indicator related to U-based CMDs, recently proposed by us. We find [Fe/H] dex, which falls between extreme estimates of the cluster's metallicity obtained using different methods or indicators. Also, the location of the RGB bump on the branch corresponds to [Fe/H] dex. We isolate 73 probable blue straggler (BS) candidates, the largest population found in NGC 3201 so far. They are more centrally concentrated than the lower red giants at the 99.2% level. Their position in the two-color diagram assumes that presumably none of them belongs to BSa of collisional origin. The luminosity function (LF) of the RGB and its features in the low part of the branch are examined and discussed. We also resolve some of the contradictory results of previous publications.
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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 | 0.000 | 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".