<i>FUSE</i>Observations of the SMC 16 Day Wolf‐Rayet Binary Sanduleak 1 (WO4+O4): Atmospheric Eclipses and Colliding Stellar Winds
Bibliographic record
Abstract
In this paper we present the results of a FUSE monitoring campaign of the SMC WO4+O4 V Wolf-Rayet binary Sanduleak 1. Our 18 spectra obtained during a little more than one orbital cycle in 2000 October combined with four archival spectra show variability in the S VI, C III, C IV, and O VI P Cygni profiles, which we attribute to emission from the shock cone resulting from the collision between the two strong winds and to atmospheric eclipses of the O star continuum light by the W-R wind. All the lines vary in concert indicating that the cooling is such that even lines such as the OVI λλ1032, 1038 doublet form in the linear part of the cone. We have also applied both a simple geometrical model and profile fits, including emission from the normal wind, extra emission from the shock cone, and the atmospheric eclipse. Adopting an orbital inclination of ~40°, we deduce a total cone opening angle of ~80° and a streaming velocity for the gas along the shock cone of ~3000 km s -1 . The luminosity ratio required to fit our spectra is L O / L W-R = 3.5, and the stellar radii are 3.5 and 12 R ☉ , respectively, for the W-R and O stars. We also present radiative driving models for this binary system having two massive stars with strong winds and discuss radiative inhibition and braking effects. In particular, we address the coupling of the O star radiation with the W-R star wind. Finally, we present a PICA hydrodynamic colliding-wind model for Sand 1. We find an opening angle for the shock cone similar to that deduced from the line-profile fitting, but significantly longer cooling lengths along the shock cone. However, the model reveals some cold gas that is stripped off the O4 surface and mixed with the hotter WO4 material, thereby accelerating its cooling. This could very well explain why shorter cooling lengths are inferred from the profile fits.
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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 | 0.001 |
| 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".