D/H ALONG THE LINE OF SIGHT OF REJ 1738+665
Bibliographic record
Abstract
We present a new D/H measurement along the sightline to REJ 1738+665, one of the hottest DA stars ( T eff ∼ 76,000 K, log g ∼ 7.85), probing a line of sight in the direction ( l = 96 89, b = 31 95) and extending over a path-length of ∼243 pc. Hot DA stars are useful sources for mapping interstellar absorption because of the lack of metal lines, which can lead to systematic errors, making REJ 1738+665 an attractive target for measuring D/H at distances and column densities intermediate between those in the Local Bubble (LB) and the more distant targets studied by the Far Ultraviolet Spectroscopic Explorer ( FUSE ). The FUSE spectrum towards REJ 1738+665 is rich in interstellar features (H i , H 2 , D i , C ii , N i , N ii , O i , Si ii , P ii , Ar i , and Fe ii ) and offers another opportunity to probe D/H and D/O outside the LB. We determine the column densities of the species mentioned above. N (H i ) is determined using archival Hubble Space Telescope data in conjunction with model atmospheres and synthetic spectra computed in non-local thermodynamic equilibrium in order to better define the stellar continuum in the vicinity of Lyα. Our analysis yields D i /H i = (1.78 ± 0.28 0.25 ) × 10 −5 and D i /O i = (5.25 ± 0.93 0.82 ) × 10 −2 along this sight line (errors stated at the 1σ level). The D/H ratio is consistent with the LB value, while the D/O ratio is only marginally consistent with the LB value (1.6σ above). We find O i /H i = (3.39 ± 0.65 0.57 ) × 10 −4 , consistent with that measured in the local interstellar medium (ISM) and N i /H i = (5.01 ± 0.86 0.77 ) × 10 −5 , somewhat lower than typical values measured in the ISM..
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.011 | 0.002 |
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".