A Non-Lte Model Atmosphere Analysis Of Hot, Hydrogen-Deficient White Dwarfs
Bibliographic record
Abstract
White dwarf stars of spectral type DO populate the hot end of the hydrogen-deficient white dwarf cooling sequence. They are characterized by a helium-rich atmosphere, a high effective temperature (Teff > 40,000 K) and a high surface gravity (log g > 7), and thus their spectrum is dominated by broad He II absorption features. Their hydrogen deficiency is thought to result from a so-called born-again evolution, during which a post-AGB star undergoes a late helium-shell flash, bringing the star back to the AGB and causing the remaining hydrogen to be burned or completely mixed in the envelope. In order to further our understanding of hydrogen-deficient white dwarf evolution, we perform a model atmosphere analysis of a large sample of DO stars. Atmospheric parameters are derived by comparing optical spectra to our new grid of non-LTE model atmospheres and synthetic spectra. We also make use of evolutionary sequences to obtain stellar masses and cooling ages. Based on these results, we discuss the physical properties of DO white dwarfs.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".