Bibliographic record
Abstract
Deep r ' and i ' images obtained with GMOS on Gemini South are used to probe the bright stellar content in the outer regions of the Centaurus Group dwarf galaxies NGC 5253 and ESO 269-G058. Red giant branch (RGB) stars are traced out to a distance of 8 kpc along the major axis of NGC 5253 and 6 kpc in ESO 269-G058. The outer regions of both galaxies are metal-poor; RGB stars located between projected major axis distances of 2 and 4 kpc in NGC 5253 have [Fe/H] ∼ -1, whereas RGB stars in the corresponding portion of ESO 269-G058 have [Fe/H] ∼ -1.8. Stars with metallicities that differ from the mean by more than a few tenths of a dex make only a modest contribution to the stellar content in the outer regions of both galaxies. A population of bright asymptotic giant branch (AGB) stars is seen in both galaxies. In the particular case of NGC 5253, roughly 1%-10% of the stellar mass may have formed during the past few hundred million years, and it is suggested that the progenitors of the two recent Type Ia supernovae in this galaxy may have formed at this time. That NGC 5253 has experienced either episodic or continuing elevated levels of star formation during the past few hundred million years is reminiscent of what is seen in other dwarf starburst galaxies, such as NGC 3077, and it is argued that the current episodes of star formation in NGC 5253 and ESO 269-G058 may have been triggered up to ∼1 Gyr in the past. Finally, a distance modulus is computed for each galaxy based on the brightness of the RGB tip, and the results are μ 0 = 27.48 ± 0.14 for NGC 5253 and 27.93 ± 0.18 for ESO 269-G058.
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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) | 0.005 | 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".