Discovery of Highly Dynamic Matter Enhancements along the Polar Axis and Equatorial Plane in the Luminous Blue Variable Binary HD 5980
Bibliographic record
Abstract
HD 5980 is a W-R+O eclipsing binary in the Small Magellanic Cloud that has attracted considerable attention since it underwent a luminous blue variable (LBV)-type outburst in 1994. Since then, intense spectroscopic and photometric monitoring have revealed the presence of periodic variability on a timescale of 6-7 hr that cannot be explained by our current understanding of the system. In this paper, we present the first results from our polarimetric observations around secondary eclipse when the assumed Wolf-Rayet (W-R) star passes in front of the assumed LBV component (phase ϕ = 0.36). These data confirm the presence of stochastic polarimetric variability on a typical timescale of ~30 minutes, reaching a very high amplitude of almost 1% on our last of five nights. At that time, we also found that the mass loss, which is responsible for the polarimetric variability, presented fluctuations in axial symmetry ranging from very rapid density enhancements along the orbital plane to polar ejections. We propose that either a fast rotator model for the W-R star or the presence of a close orbiting neutron star could qualitatively explain the observed polarimetric, spectroscopic, and photometric behavior. The evidence presented in this paper is crucial for an understanding of the erratic behavior of this important binary and should be taken into account in any consistent model of the 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".