Decretion disc evolution and neutron star accretion in short-period eccentric Be/X-ray binaries
Bibliographic record
Abstract
ABSTRACT We examine Be star discs in highly eccentric Be/X-ray systems. We use a three-dimensional smoothed particle hydrodynamics code to model the structure of the Be star disc and investigate its interactions with the secondary star over time. We use system parameters consistent with the eccentric, short-period (P$\approx$ 16 d) Be/X-ray binary A0538-66 as the basis for our models. We explore a range of system geometries by incrementally varying the misalignment angle of the neutron star’s orbital plane with respect to the primary star’s equatorial plane to cover a complete range from coplanar prograde to coplanar retrograde. For all simulations, we follow the evolution of the disc’s total mass and angular momentum as well as the average eccentricity and inclination with respect to the equatorial planes of both the primary and secondary. We also determine the neutron star accretion rates. We find that the high eccentricity of the binary orbit causes all calculated disc parameters to vary with orbital phase in all models. The amplitude of these variations is negatively correlated with misalignment angle for models with misalignment angles less than 90$^{\circ }$, and positively correlated for models with misalignment angles greater than 90$^{\circ }$. Accretion rates are affected by the number of particles the neutron star interacts with as well as the length of the interaction time between the particles and the neutron star. We find that accretion rates are largest for models with misalignment angles less than 90$^{\circ }$, and smaller for models with those greater than 90$^{\circ }$.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 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".