Quiescent Dense Gas in Protostellar Clusters: The Ophiuchus A Core
Bibliographic record
Abstract
We present combined BIMA interferometer and IRAM 30 m telescope data of N 2 H + 1-0 line emission across the nearby dense star-forming core Ophiuchus A at high linear resolution (e.g., ~1000 AU). Six maxima of integrated line intensity are detected, which we designate Oph A-N1 through N6. The N4 and N5 maxima coincide with the starless continuum objects SM1 and SM2, respectively, but the other maxima do not coincide with previously identified objects. In contrast, relatively little N 2 H + 1-0 emission coincides with the starless object SM2 and the Class 0 protostar VLA 1623. The FWHM of the N 2 H + 1-0 line, Δ V , varies by a factor of ~5 across Oph A. Values of Δ V < 0.3 km s -1 are found in 14 locations in Oph A, but only that associated with N6 is both well defined spatially and larger than the beam size. Centroid velocities of the line, V LSR , vary relatively little, having an rms of only ~0.17 km s -1 . Small-scale V LSR gradients of less than 0.5 km s -1 over ~0.01 pc are found near SM1, SM1N, and SM2 but not N6. The low N 2 H + abundances of SM2 or VLA 1623 relative to SM1, SM1N, or N6 may reflect relatively greater amounts of N 2 adsorption onto dust grains in their colder and probably denser interiors. The low Δ V of N6, i.e., 0.193 km s -1 FWHM, is only marginally larger than the FWHM expected from thermal motions alone, suggesting that turbulent motions in the Oph A core have been reduced dramatically at this location. The nondetection of N6 in previous thermal continuum maps suggests that interesting sites possibly related to star formation may be overlooked in such data.
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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 | 0.003 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.011 | 0.001 |
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".