Near-IR spectroscopy of planetary nebulae precursors
Bibliographic record
Abstract
\n \nWe present near-IR spectroscopy of a sample of 30\nIRAS sources recently identified as late AGB stars, post-AGB stars or early\n PNe. The spectra obtained are \ncentered at various wavelengths covering the molecular\nhydrogen $v=1$\n $\\rightarrow $0 S(1) 2.122 μm and $v=2$\n $\\rightarrow$1 \nS(1) 2.248 μm emission lines, the recombination lines of hydrogen \nBrγ 2.166 μm, Pfγ 3.741 μm and Brα \n4.052 μm, and the CO[ $v=2$\n $\\rightarrow$0] first overtone \nbandhead at 2.294 μm. As a result of these observations we have \ndetected molecular hydrogen emission for the first time in 9 of these\nsources and confirmed a previous detection by Weintraub et al. \n([CITE]). This increases from 4 to 13 the total number of proto-PNe detected \nin molecular hydrogen. In most cases, the positive detections \nalso show emission in the recombination lines of hydrogen (with the exception\nof IRAS 17150-3224) indicating that the onset of molecular hydrogen \nemission takes place in the post-AGB phase, very shortly before the \nnebula becomes ionized. When the molecular \nhydrogen is fluorescence-excited the detection rate is found to \nbe directly correlated with the evolutionary stage of the central star,\nrather than with the nebular morphology. When the temperature of the \ncentral star is hot enough, fluorescence excitation can be\ninduced by the absorption of UV photons escaping from the \nrapidly evolving central post-AGB star. In contrast, shock-excited \nmolecular hydrogen is detected only in strongly bipolar proto-PNe, \nsometimes even at an early stage in the post-AGB phase. Shock excitation \nis the consequence \nof the interaction of the fast post-AGB wind with the slow wind material \nejected during the AGB. The strong correlation of shock-excited molecular\nhydrogen emission with bipolarity found \nconfirms the result previously reported by Kastner et al. ([CITE]) in evolved \nPNe. However, our results show that this correlation does not \nexist in the case of fluorescence-excited molecular hydrogen. \n \n
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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".