Bibliographic record
Abstract
Broadband near-infrared images are used to probe the photometric properties of the brightest asymptotic giant branch (AGB) stars within 2' of the centers of the dwarf elliptical galaxies NGC 147, NGC 185, and NGC 205. Sequences originating from oxygen-rich M giants and C stars are clearly distinguished on the ( K , H - K ) and ( K , J - K ) color-magnitude diagrams. Based on the peak brightness and color of the M giant sequences, ages of 1 and 0.1 Gyr are predicted for the most recent significant star-forming events in NGC 185 and NGC 205, respectively. The bolometric luminosity function of M giants in NGC 205 is flatter than in NGC 185, in agreement with studies at wavelengths shortward of 1 μm. The most luminous AGB stars in NGC 147 are well mixed with fainter stars throughout the area surveyed in this galaxy, and the peak brightness of the M giant sequence indicates that the most recent significant star-forming activity occurred ∼3 Gyr in the past. The C star contents of the three galaxies are compared in two ways. First, the notion of a specific frequency measurement for C stars, in which C star counts per unit magnitude are normalized to a common integrated K -band brightness using published surface photometry, is introduced. The specific frequencies of C stars outside the areas of most recent star formation agree in all three galaxies. Second, comparisons are made using the integrated brightness from C stars, which is normalized to the integrated light from M giants and the integrated light from all stars. The fractional contribution made by C stars to the total AGB light in the K -band is found to be highest in NGC 147 and lowest in the central regions of NGC 205, which is qualitatively consistent with model predictions. The fractional contribution that C stars make to the total K -band light is found to be constant both within and between galaxies, with C stars contributing 2% of the total K -band light. We conclude that, when averaged over timescales of a few gigayears, these galaxies have turned similar fractions of gas and dust, normalized according to total galaxy mass, into stars. We argue that the material for star formation likely originated in well-regulated reservoirs and demonstrate that the mass of gas needed to fuel star formation during intermediate epochs could have been supplied by winds from evolved stars. Finally, multiepoch data are used to investigate the incidence of long-period variables (LPVs) in NGC 185 and NGC 205. While tight constraints cannot be placed on the LPV content of NGC 205, roughly 70% of the stars with M K between -7.5 and -8.0 in the central regions of NGC 185 appear to be LPVs with amplitudes similar to those of LPVs in the LMC.
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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 | 0.000 |
| 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".