Beryllium in F and G Field Dwarfs from High‐Resolution Canada‐France‐Hawaii Telescope Spectra
Bibliographic record
Abstract
It is important to add observations of Be to the huge arsenal of Li observations in order to identify the mechanisms operating in stellar interiors that alter the surface composition of the light elements. Beryllium is more resistant to destruction than is Li, so information on the abundances of both Li and Be reveals more information on the internal processes than either element does alone. We have made observations of Be II at 3131 A in 46 solar-type stars from the Canada-France-Hawaii Telescope with high spectral resolution and high signal-to-noise ratios (S/N). Our Li I 6707 A data for 39 of these stars come from our high-resolution, high-S/N observations with the University of Hawai`i 88 inch (2.2 m) telescope and coude spectrograph and Keck I High Resolution Echelle Spectrometer and, for six stars, from the literature. Most of the stars in our sample are F and G dwarfs with Teff between 6100 and 6600 K and with [Fe/H] between -0.6 and +0.2. The abundances of Be have been determined through spectrum synthesis, while Li has been analyzed as a blend to find the Li abundance. We find a large range in both Li and Be in these stars; for Be it is at least 2.5 dex and for Li at least 3 dex. However, there is an excellent correlation between Li and Be, as discovered by Deliyannis et al. from a smaller sample. We find that in the range of Teff of 5850 K (near the Li peak in open clusters) to 6680 K (at the bottom of the Li gap as defined by the Hyades), Li and Be appear to be depleted together. The slope of this remarkable logarithmic relation is 0.36: as Li is reduced by a factor of 10, Be is reduced by only 2.2 times. There is some scant evidence for a change in the slope between the cooler stars and the hotter stars such that the cooler stars deplete more Li relative to Be than the hotter stars. These results are well matched by models that incorporate rotationally induced slow mixing of the stellar surface material with the deeper layers of the star.
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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 | 0.002 | 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) | 0.001 | 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".