Bibliographic record
Abstract
VLBI measurements of the size of SN 1979C in M100 (NGC 4321) in the Virgo Cluster, from t = 3.7 yr after the explosion, show an expansion ∝ t m , which is, with m = 0.95 ± 0.03, almost consistent with being free for 22 years. The last size measurement, at t = 22 yr, may indicate for the first time a change of the expansion of the supernova and suggests, as an alternative, free expansion ∝ t m with m = 1.00 ± 0.05 up to t b ~ 17 yr followed by marginally significant deceleration with m = 0.74 ± 0.17. The possible deceleration could be weaker within the errors for t b < 17 yr or stronger for t b > 17 yr. With the assumption for the density profile of the circumstellar medium (CSM) of ρ CSM ∝ r - s , we derive a model-dependent value of s = 1.95 up to a distance from the progenitor, r = r b , that corresponds to t b ~ 17 yr, which changes to s ≲ 1.5 for r > r b . For a kinetic energy of the shocked ejecta and CSM shells of E kin = 10 51 ergs, our results require a mass loss to wind velocity ratio for the progenitor of w / w ~ 1 × 10 -5 M ☉ yr -1 per w = 10 km s -1 , an order of magnitude smaller than estimated from radio light-curve fitting. The swept-up mass at t = 22 yr is then M sw = 0.3 M ☉ and the inferred mass of the shocked ejecta M shock-ej = 2 M ☉ . Our last observations give an image of a barely resolved source with a first hint on the structure of the supernova, consistent with being circular within 9% and possibly center filled. The expanding shock front method (ESM) of combining the transverse radio expansion velocities with the radial optical velocities gives direct distance estimates to M100, with standard errors of D = 16.5 ± 2.5 to 19.8 ± 3.0 Mpc, depending on whether the supernova has a bright center or is a shell without such a center. These estimates are comparable with those from Cepheid observations (e.g., 16.1 and 15.2 Mpc).
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".