Strong absorption by interstellar hydrogen fluoride:<i>Herschel</i>/HIFI observations of the sight-line to G10.6–0.4 (W31C)
Bibliographic record
Abstract
We report the detection of strong absorption by interstellar hydrogen fluoride along the sight-line to the submillimeter continuum source G10.6–0.4 (W31C). We have used <i>Herschel<i/>'s HIFI instrument, in dual beam switch mode, to observe the 1232.4763 GHz <i>J<i/> = 1–0 HF transition in the upper sideband of the Band 5a receiver. The resultant spectrum shows weak HF emission from G10.6–0.4 at LSR velocities in the range –10 to –3 km s<sup>-1<sup/>, accompanied by strong absorption by foreground material at LSR velocities in the range 15 to 50 km s<sup>-1<sup/>. The spectrum is similar to that of the 1113.3430 GHz 1<sub>11<sub/>–0<sub>00<sub/> transition of para-water, although at some frequencies the HF (hydrogen fluoride) optical depth clearly exceeds that of para-H<sub>2<sub/>O. The optically-thick HF absorption that we have observed places a conservative lower limit of 1.6×10<sup>14<sup/> cm<sup>-2<sup/> on the HF column density along the sight-line to G10.6–0.4. Our lower limit on the HF abundance, 6×10<sup>-9<sup/> relative to hydrogen nuclei, implies that hydrogen fluoride accounts for between ~30% and 100% of the fluorine nuclei in the gas phase along this sight-line. This observation corroborates theoretical predictions that – because the unique thermochemistry of fluorine permits the exothermic reaction of F atoms with molecular hydrogen – HF will be the dominant reservoir of interstellar fluorine under a wide range of conditions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.000 | 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 teacher head, 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".