<i>s</i>‐Process Nucleosynthesis in Asymptotic Giant Branch Stars: A Test for Stellar Evolution
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Bibliographic record
Abstract
[abridged] We study the s-process in AGB stars using three different stellar evolutionary models computed for a 3Msun and solar metallicity star. First we investigate the formation and the efficiency of the main neutron source. We parametrically vary the number of protons mixed from the envelope into the C12 rich core. For p/C12 > 0.3, mainly N14 is produced, which represent a major neutron poison. The amount of C12 in the He intershell and the maximum value of the time-integrated neutron flux are proportional. Then we generate detailed s-process calculations on the basis of stellar evolutionary models constructed with three different codes. One code considers convective hydrodynamic overshoot that depends on a free parameter f, and results in partial mixing beyond convective boundaries, the most efficient third dredge up and the formation of the C13 pocket. For the other two codes an identical C13 pocket is introduced in the post-processing nucleosynthesis calculations. The models generally reproduce the spectroscopically observed s-process enhancements. The results of the cases without overshoot are remarkably similar. The code including hydrodynamic overshoot produces a He intershell composition near to that observed in H-deficient central stars of planetary nebulae. As a result of this intershell dredge up the neutron fluxes have a higher efficiency, both during the interpulse periods and within thermal pulses. The s-element distribution is pushed toward the heavier s-process elements and large abundances of neutron-rich isotopes fed by branching points in the s-process path are produced. Several observational constraints are better matched by the models without overshoot. Our study need to be extended to different masses and metallicities and in the space of the free overshoot parameter f.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it