CO in H<scp>i</scp>Self‐absorbed Clouds in Perseus
Bibliographic record
Abstract
We have observed 12 CO J = 2 → 1 and J = 1 → 0 and 13 CO J = 1 → 0 emission in two regions of H I self-absorption (HISA) in Perseus: a small, isolated HISA feature called the "globule" and a more extended HISA cloud called the "complex." Using both large velocity gradient and Monte Carlo radiative transfer codes, we found that in the globule N ( 12 CO) < 6.0 × 10 15 cm -2 , which, using photodissociation region (PDR) models, implies that N (H 2 ) < 9.9 × 10 20 cm -2 . In the complex we found that the H 2 column densities were in the range (1.2-2.2) × 10 21 cm -2 . By comparing the HISA and CO observations we were able to constrain the physical conditions and atomic gas fraction ( f ). In the globule, 8 K < T spin < 22 K and 0.02 < f < 0.2, depending on whether the (unknown) gas density was 10 2 , 10 3 , or 10 4 cm -3 . In the complex, 12 K < T spin < 24 K and 0.02 < f < 0.05, and we were also able to constrain the gas density (100 cm -3 < n < 1200 cm -3 ). These results imply that the gas in the HISA clouds is colder and denser than that usually associated with the atomic ISM and, indeed, is similar to that seen in molecular clouds. The small atomic gas fractions also imply that there is a significant molecular component in these HISA clouds, even when little or no 12 CO is detected. The level of 12 CO detected and the visual extinction due to dust is consistent with the idea that these HISA clouds are undergoing a transition from the atomic to molecular phase.
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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 | 0.000 |
| 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 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".