The Central Regions of M31 in the 3-5 μm Wavelength Region
Bibliographic record
Abstract
Images obtained with NIRI on the Gemini North telescope are used to investigate the photometric properties of the central regions of M31 in the 3-5 μm wavelength range. The light distribution in the central arcsecond differs from what is seen in the near-infrared in the sense that the difference in peak brightness between P1 and P2 is larger in M ' than in K '; no obvious signature of P3 is detected in M '. These results can be explained if there is a source of emission that contributes ∼20% of the peak M ' light of P1, has an effective temperature of no more than a few hundred K, and is located between P1 and P2. Based on the red K - M ' color of this source, it is suggested that the emission originates in a circumstellar dust shell surrounding a single bright asymptotic giant branch (AGB) star. Tests of this hypothesis are described. A bright source that is ∼8'' from the center of the galaxy is also detected in M '. This object has red colors and an absolute brightness in M ' that is similar to the most highly evolved AGB stars in the solar neighborhood; hence, it is likely to be a very evolved AGB star embedded in a circumstellar envelope. The K -band brightness of this star is close to the peak expected for AGB evolution, and an age of only a few hundred million years is estimated, which is comparable to that of the P3 star cluster. Finally, using high angular resolution near-infrared adaptive optics images as a guide, a sample of unblended AGB stars outside of the central few arcseconds is defined in L '. The ( L ', K - L ') color-magnitude diagram of these sources shows a dominant AGB population with a peak L ' brightness and a range of K - L ' colors that are similar to those of the most luminous M giants in the Galactic bulge.
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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 | 0.001 | 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) | 0.002 | 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".