The distance to the supernova remnant CTB 87 and the radial velocity of the perseus arm toward l=75°, derived from H I and CO observations
Bibliographic record
Abstract
We present the results of an analysis of H I data from the Canadian Galactic Plane Survey and new CO observations in the direction of the radio-bright, filled-center supernova remnant (SNR) CTB 87. Our CO (1-0) and CO (3-2) data reveal evidence for associated molecular material surrounding parts of CTB 87 at a systemic velocity of v(LSR) approximate to -58 km s(-1). There is no evidence of interacting H I or the existence of a stellar wind bubble around the SNR. This indicates a supernova explosion of Type II and a B2 or later type progenitor star. We established a new distance of 6.1+/-0.9 kpc based on the extinction-distance relation introduced by Foster & Routledge, which agrees with a location within the Perseus spiral arm. Our result contradicts previous distance estimates based on H I absorption measurements, which indicated a distance of about 12 kpc, using a. at rotation curve. This discrepancy arises from a significant shift of the radial velocities in the direction of CTB 87 due to a spiral shock. The new distance reduces the derived physical size and the luminosity of CTB 87 by factors of 2 and 4, respectively. The properties of this plerionic SNR are then more similar to those of the other SNRs of its kind except the Crab Nebula, which is an exceptionally luminous object.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.001 |
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".