The Period Changes of Polaris
Bibliographic record
Abstract
The evolutionary changes in pulsation period for the Cepheid Polaris are reinvestigated using archival observational material (radial velocities, photometry, and eye observations) over the interval 1844 to the present, including new photometry for the star obtained in 2003–2004. The star's pulsation period increased at a rate of 4.5 s yr−1 during that interval, with the exception of a brief hiatus between 1963 and 1966, when it suddenly decreased, possibly as a result of a brief reduction in average stellar radius amounting to −0.055%. At roughly the same time, the pulsation amplitude of Polaris underwent a marked change. Prior to 1963 the V amplitude was in excess of about 0.1 mag, possibly decreasing at a rate of 0.019 mag century−1. Following the hiatus of 1963–1966, the pulsation amplitude underwent a sharp decline and now appears to be erratic on a cycle‐to‐cycle basis, always smaller than 0.05 mag. The rapid rate of period increase for Polaris is consistent with a first crossing of the Cepheid instability strip, while the hiatus of 1963–1966 and sudden decrease in pulsation amplitude thereafter suggest that the star may have left the instability strip for first crossers at that time, leaving it near the center of the instability strip for Cepheids in higher crossing modes.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".