High‐Mass Star Formation. I. The Mass Distribution of Submillimeter Clumps in NGC 7538
Bibliographic record
Abstract
We present submillimeter continuum maps at 450 and 850 microns of a 12 x 8 arcminute region of the NGC 7538 high-mass star-forming region, made using the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. We used an automated clump-finding algorithm to identify 67 clumps in the 450 micron image and 77 in the 850 micron image. Contrary to previous studies, we find a positive correlation between high spectral index, alpha, and high submillimeter flux, with the difference being accounted for by different treatments of the error beam. We interpret the higher spectral index at submillimeter peaks as a reflection of elevated dust temperature, particularly when there is an embedded infrared source, though it may also reflect changing dust properties. The clump mass-radius relationship is well-fit by a power law of the form M \\propto R^(-x) with x = 1.5-2.1, consistent with theories of turbulently-supported clumps. According to our most reliable analysis, the high-mass end (approx. 100-2700 M_sun) of the submillimeter clump mass function in NGC 7538 follows a Salpeter-like power law with index 2.0 +/- 0.3. This result agrees well with similar studies of lower-mass regions rho Oph and Orion B. We interpret the apparent invariance of the shape of the clump mass function over a broad range of parent cloud masses as evidence for the self-similarity of the physical processes which determine it. This result is consistent with models which suggest that turbulent fragmentation, acting at early times, is sufficient to set the clump mass function.
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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".