Polarimetric Variations of Binary Stars. I. Numerical Simulations for Circular and Eccentric Binaries in Thomson Scattering Envelopes
Bibliographic record
Abstract
We present numerical simulations of the polarimetric variations produced by a binary star placed at the center of an empty spherical cavity inside a circumbinary ellipsoidal and optically thin envelope. Thomson single-scattering is considered along with pre- and postscattering extinction factors which produce a time-varying optical depth. The orbits are circular or eccentric. The mass ratio (and luminosity ratio) is in general equal to 1.0. As a function of the orbital (and envelope) inclination, the polarization follows a sin 2 ( i ) law. High polarization levels will result from a high inclination, a high optical depth, a flat envelope, or a big central cavity. Polarimetric variations are more apparent for a low inclination, a high optical depth, a flat envelope, a small cavity, or an orbit that brings the stars close to the inner edge of the cavity. It is then shown that the 1978 BME (Brown, McLean, & Emslie) model can be used to find the orbital inclination if it is ≳45°, even though this model does not include variable absorption effects as in our simulations. The geometry (flatness of the envelope, size of the central cavity) and size of the orbit have no significant influence on the inclination found by the BME model. For eccentric orbits, single-periodic variations (variations seen once per orbit) appear for eccentricities as low as 0.10. As the eccentricity increases, these single-periodic variations dominate over the double-periodic (seen twice per orbit) ones. The inclinations found by the BME model with the first-order coefficients are then more reliable than those found with the second-order coefficients, especially for the highest eccentricities. For low eccentricities, e ≲ 0.3, the inclinations can be found with the first or second-order coefficients, if i > 20° and i > 45°, respectively. For the high eccentricities, 0.3 < e < 0.6, only the first-order coefficients should be used, if i > 10°. Since with polarimetric observations the true inclination is not known a priori , we discuss how to use the BME model in that context.
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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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".