NEAR-INFRARED SPECTROSCOPY OF INFRARED-EXCESS STELLAR OBJECTS IN THE YOUNG SUPERNOVA REMNANT G54.1+0.3
Bibliographic record
Abstract
We present the results of broadband near-infrared spectroscopic observations of the recently discovered mysterious stellar objects in the young supernova remnant G54.1+0.3. These objects, which show significant mid-infrared-excess emission, are embedded in a diffuse loop structure of ∼1' in radius. Their near-infrared spectra reveal characteristics of late O- or early B-type stars with numerous H and He i absorption lines, and we classify their spectral types to be between O9 and B2 based on an empirical relation derived here between the equivalent widths of the H lines and stellar photospheric temperatures. The spectral types, combined with the results of spectral energy distribution fits, constrain the distance to the objects to be 6.0 ± 0.4 kpc. The photometric spectral types of the objects are consistent with those from the spectroscopic analyses, and the extinction distributions indicate a local enhancement of matter in the western part of the loop. If these objects originate via triggered formation by the progenitor star of G54.1+0.3, then their formations likely began during the later evolutionary stages of the progenitor, although a rather earlier formation may still be possible. If the objects and the progenitor belong to the same cluster of stars, then our results constrain the progenitor mass of G54.1+0.3 to be between 18 and ∼35 M ☉ and suggest that G54.1+0.3 was either a Type IIP supernova or, with a relatively lower possibility, Type Ib/c from a binary system.
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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 | 0.000 | 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 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".