Interstellar Deuterium, Nitrogen, and Oxygen Abundances toward GD 246, WD 2331−475, HZ 21, and Lanning 23: Results from the<i>FUSE</i>Mission
Bibliographic record
Abstract
The interstellar abundances of D I, N I, and O I in the local ISM are studied using high-resolution spectra of four hot white dwarfs. The spectra of GD 246, WD 2331-475, HZ 21, and Lan 23 were obtained with the Far Ultraviolet Spectroscopic Explorer ( FUSE ) in the wavelength range 905-1187 Å. The line of sight to GD 246 probes the Local Interstellar Cloud and at least one other H I cloud inside the Local Bubble, which contains most of the gas seen along this line of sight. The column densities of H I, C II*, S II, and Si II are measured using archival Hubble Space Telescope STIS echelle-mode observations. The H I column density is determined by fitting the strong damping wings of interstellar Lyα and using a model atmosphere to account for the stellar continuum. The sight line-averaged ratios for GD 246 are D I/H I = 1.51 × 10 -5 , O I/H I = 3.63 × 10 -4 , and D I/O I = 4.17 × 10 -2 (uncertainties are 2 σ). This line of sight provides the fourth reliable FUSE measurement of the Local Bubble D/H ratio. For the WD 2331-475 line of sight, we find sight line-averaged ratios D I/O I = 5.13 × 10 -2 and D I/N I = 4.57 × 10 -1 . Toward HZ 21 the sight line-averaged ratios are D I/O I = 4.57 × 10 -2 and D I/N I = 4.27 × 10 -1 . In the higher column density sight line to Lan 23, the sight line-averaged ratios are D I/O I = 3.24 × 10 -2 and D I/N I = 3.16 × 10 -1 . Molecular hydrogen, corresponding to rotational levels J ≤ 3, is clearly seen along this line of sight. No reliable H I measurements are available for WD 2331-475, HZ 21, or Lan 23. We combine the different abundance ratios computed here with previous published values to produce revised FUSE abundance ratios for D I/H I, O I/H I, N I/H I, D I/N I, D I/O I, and O I/N I.
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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 | 0.000 |
| Science and technology studies | 0.001 | 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".