An optical investigation of the Dumbbell planetary nebula (M27, NGC 6583)
Bibliographic record
Abstract
Imaging Fourier transform spectroscopy is used to obtain multiwavelength observations of the M27 planetary nebula's optical gas complex. The data set allows a complete cartography of the nebula's morphological properties, of its density and temperature structures in its low-excitation zone, and of its gas excitation. Radial profiles in peak intensity indicate that the nebula is radiation-bounded along its highly inhomogeneous and clumpy minor axis. The diffuse major axis show a monotonic decrease with increasing distance from the central star and appears to be matter-bounded. Clumps, said to be formed of numerous small-scale features referred as ‘knots’ in the literature, are mostly located in the low-excitation outer shell. The standard low-excitation [S ii] and [N ii] diagnostics reveal mean density and temperature, respectively, estimated at 80 cm−3 and 10 115 K in the nebula's outer layers. Temperature fluctuations, on the plane of the sky, show a decreasing trend with increasing angular scale. A lower limit of 0.023 is obtained for the amplitude |$t^{2}_{{\rm V}}$| of the volumetric temperature fluctuations. This indicates that temperature inhomogeneities could play a role in the solution of the abundance discrepancy problem.
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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 | 0.002 | 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) | 0.001 | 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".