Limits to Interstellar C<sub>4</sub>and C<sub>5</sub>toward ζ Ophiuchi
Bibliographic record
Abstract
We have made a sensitive search for the origin bands in the known electronic transitions of the linear carbon chains C 4 and C 5 at 3789 and 5109 Å toward ζ Oph ( A v ≤ 1). The incentive was a recent detection of C 3 in this interstellar cloud with a column density of 1.6 × 10 12 cm -2 , plus the availability of laboratory gas phase spectra of C 4 and C 5 . Further, some models of diffuse interstellar clouds predict that the abundance of these latter species should be within an order of magnitude of C 3 . Despite achieving a signal-to-noise ratio (S/N) of 2300 to 2600 per pixel at a resolution of ~110,000, the searches were negative, leading to 3 σ upper limits to the column density of N (C 5 )= 2 × 10 11 cm -2 and N (C 4 )= 4 × 10 12 to 10 13 cm -2 where these values rely on theoretically calculated oscillator strengths. The implication of these limits is discussed along with the identification of molecules for study in future attempts to identify the carriers of the stronger diffuse interstellar bands.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".