The Long‐Term Behavior of the Semiregular M Supergiant Variable BC Cygni
Bibliographic record
Abstract
The long‐term brightness changes in the M supergiant, type C semiregular variable, Type II supernova progenitor BC Cyg from 1890 to the present are examined using archival data obtained from photographic plates in the collections of Harvard College Observatory and Sternberg Astronomical Institute, in conjunction with AAVSO observations. BC Cyg pulsates with a period close to 700 days but underwent a 0.5 mag increase in brightness between 1900 and 2000, in conjunction with a decrease in pulsation period from 699 to 687 days. Such changes appear to be evolutionary in origin, representing a small contraction of the star associated with a slight decrease in luminosity. Its evolutionary mass is estimated to be ∼19 M ⊙ from its membership in Berkeley 87, a feature that also permits it to be used to test the M supergiant period‐luminosity relation.
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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 | 0.000 |
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".