Bibliographic record
Abstract
Progenitors of PN play an important role in the chemical enrichment of the Galaxy because He and significant amounts of C and N are produced by nucleosynthesis during the MS, RG, and AGB stages of their evolution. These elements are brought to the surface of the star by convection events called dredge ups (Iben, 1991). The first dredge up occurs in all stars on the RGB following the exhaustion of H in the core. Convection extending into the interior brings material processed in the CNO cycle to the surface. The second dredge-up occurs only in higher mass (≥3 M ⊙ ) stars during the early AGB phase and results in an increase in the surface abundance of 4 He and 14 N at the expense of 12 C and 16 O. The third dredge-up occurs on the AGB after each He-shell flash, resulting in He, C, and s -process elements being brought to the surface (Renzini and Voli, 1981). This repeated enhancement of C abundance in the stellar surface may in some stars bring the C/O ratio to be greater than unity. Since the less abundant of these two elements is completely tied up in the CO molecule, the photospheric spectrum of the star will change from O-based (e.g., TiO and VO) to C-based (e.g., C 2 and CN), and a carbon star is created (see Section 10.2). Stellar winds during the AGB eject these elements from the stellar surface and therefore enrich the interstellar medium.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.041 | 0.045 |
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".