The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128
Bibliographic record
Abstract
Deep, near-infrared images obtained with adaptive optics (AO) systems on the Gemini North and Canada-France-Hawaii telescopes are used to investigate the bright stellar content and central regions of the nearby elliptical galaxy Maffei 1. Stars evolving on the upper asymptotic giant branch (AGB) are resolved in a field 3' from the center of the galaxy. The locus of bright giants on the ( K , H - K ) color-magnitude diagram is consistent with a population of stars like those in Baade's Window reddened by E ( H - K ) = 0.28 ± 0.05 mag. This corresponds to A V = 4.5 ± 0.8 mag and is consistent with previous estimates of the line-of-sight extinction computed from the integrated properties of Maffei 1. The AGB tip occurs at K = 20.0, which corresponds to M K = -8.7; hence, the AGB tip brightness in Maffei 1 is comparable to that in M32, NGC 5128, and the bulges of M31 and the Milky Way. The near-infrared luminosity functions (LFs) of bright AGB stars in Maffei 1, M32, and NGC 5128 are also in excellent agreement, both in terms of overall shape and the relative density of infrared-bright stars with respect to the fainter stars that dominate the light at visible and red wavelengths. It is concluded that the brightest AGB stars in Maffei 1, NGC 5128, M32, and the bulge of M31 trace an old, metal-rich population, rather than an intermediate-age population. It is also demonstrated that Maffei 1 contains a distinct red nucleus, and this is likely the optical signature of low-level nuclear activity and/or a distinct central stellar population. Finally, there is an absence of globular clusters brighter than the peak of the globular cluster LF in the central 700 pc × 700 pc of Maffei 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 | 0.002 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".