A<i>SPITZER</i>STUDY OF 21 AND 30 μm EMISSION IN SEVERAL GALACTIC CARBON-RICH PROTOPLANETARY NEBULAE
Bibliographic record
Abstract
We have carried out mid-infrared spectroscopy of seven Galactic protoplanetary nebulae (PPNs) using the Spitzer Space Telescope . They were observed from 10 to 36 μm at relatively high spectral resolution, R ≈ 600. The sample was chosen because they all gave some evidence in the visible of a carbon-rich chemistry. All seven of the sources show the broad, unidentified 21 μm emission feature; three of them are new detections (IRAS 06530 − 0213, 07430+1115, and 19477+2401) and the others are observed at higher signal-to-noise ratio than in previous spectra. These have the same shape and central wavelength (20.1 μm) as found in the Infrared Space Observatory ( ISO ) spectra of the brighter PPNs. The 30 μm feature was seen in all seven objects. However, it is not resolved into two separate features (26 and 33 μm) as was claimed on the basis of ISO spectra, which presumably suffered from the noisy detector bands in this region. All showed the aromatic infrared bands at 11.3, 12.4, and 13.3 μm. Five of these also appear to have the C 2 H 2 molecular band at 13.7 μm, one in absorption and four in emission. This is extremely rare, with only one other evolved star, IRC+10216, in which C 2 H 2 emission has been observed. Four also possessed a broad, unidentified emission feature at 15.8 μm that may possibly be related to the 21 μm feature. Model fits were made to the spectral energy distributions for these PPNs to determine properties of the detached circumstellar envelopes. The 21 μm feature has been seen in all Galactic carbon-rich PPNs observed, and thus its carrier appears to be a common component of the outflow around these objects.
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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 | 0.000 |
| Science and technology studies | 0.001 | 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".