Variations in D/H and D/O from New<i>Far Ultraviolet Spectroscopic Explorer</i>Observations
Bibliographic record
Abstract
We use data obtained with the Far Ultraviolet Spectroscopic Explorer ( FUSE ) to determine the interstellar abundances of D I, N I, O I, Fe II, and H 2 along the sight lines to WD 1034+001, BD +39 3226, and TD1 32709. Our main focus is on determining the D/H, N/H, O/H, and D/O ratios along these sight lines, with log N (H) > 20.0, that probe gas well outside of the Local Bubble. Hubble Space Telescope ( HST ) and International Ultraviolet Explorer ( IUE ) archival data are used to determine the H I column densities along the WD 1034+001 and TD1 32709 sight lines, respectively. For BD +39 3226, a previously published N (H I) is used. We find (D/H) × 10 5 = 2.14 , 1.17 , and 1.86 and (D/O) × 10 2 = 6.31 , 5.62 , and 7.59 for the WD 1034+001, BD +39 3226, and TD1 32709 sight lines, respectively (all 1 σ). The scatter in these three D/H ratios exemplifies the scatter that has been found by other authors for sight lines with column densities in the range 19.2 < log N (H) < 20.7. The D/H ratio toward WD 1034+001 and all of the D/O ratios derived here are inconsistent with the Local Bubble value and are some of the highest in the literature. We discuss the implications of our measurements for the determination of the present-epoch abundance of deuterium and for the different scenarios that try to explain the D/H variations. We present a study of D/H as a function of the average sight line gas density, using the ratios derived in this work as well as ratios from the literature, which suggests that D/H decreases with increasing gas volume density. Similar behaviors by other elements such as Fe and Si have been interpreted as the result of depletion into dust grains.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".