An evidence-based assumption that helps to reduce the discrepancy between the observed and predicted 7Be abundances in novae
Bibliographic record
Abstract
ABSTRACT Recent spectroscopic measurements of the equivalent widths of the resonant Be ii doublet and Ca ii K lines and their ratios in expanding nova ejecta indicate surprisingly high abundances of 7Be with a typical mass fraction Xobs(7Be) = 10−4. This is an order of magnitude larger than theoretically predicted values of Xtheor(7Be) ∼ 10−5 for novae. We use an analytical solution of the 7Be production equations to demonstrate that Xtheor(7Be) is proportional to the 4He mass fraction Y in the nova accreted envelope and then we perform computations of 1D hydrostatic evolution of the $1.15\, \mathrm{M}_\odot$ CO nova model that confirm our conclusion based on the analytical solution. Our assumption of enhanced 4He abundances helps to reduce, although not completely eliminate, the discrepancy between Xobs(7Be) and Xtheor(7Be). It is supported by ultraviolet, optical, and infrared spectroscopy data that reveal unusually high values of Y in nova ejecta. We also show that a significantly increased abundance of 3He in nova accreted envelopes does not lead to higher values of Xtheor(7Be) because this assumption affects the evolution of nova models resulting in a decrease of both their peak temperatures and accreted masses and, as a consequence, in a reduced production of 7Be.
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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 | 0.002 | 0.010 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".