The magnetic field and circumstellar environment of the helium-strong star HD 36485 =δ Ori C
Bibliographic record
Abstract
Extensive Hα spectroscopy of the cool, helium-strong star δ Ori C obtained over two decades has enabled a detailed analysis of the variable Hα emission observed in this sharp-lined and strongly magnetic B3V star. Radial velocity measurements from these and other spectra have also confirmed the binary nature of the star, the first detection of the secondary being provided, and permitted an improved determination of the system's orbital parameters. The amplitude of the radial velocities and a preliminary spectroscopic analysis indicate that the secondary component is an early A-type star. Disentangling the contribution of the two components to the Balmer line profiles, we determine an effective temperature for δ Ori C slightly larger than previously adopted in the literature. The Hα emission is variable with a period of 1.477 75 ± 0.000 04 d, assumed to be the rotation period of the primary component. After removal of the binary system's photospheric contribution to the Hα line, we find that the emission arises from two distinct, but asymmetrical, optically translucent circumstellar clouds. When strongest the emission peaks have intensities of approximately 15 per cent of the continuum level at about 150 km s−1 on either side of the line centre, and emission is apparent to ±225 km s−1, or 6 R* above the photosphere if we assume that the magnetic field forces the circumstellar material into rigid rotation about the star. New 6 cm Very Large Array radio measurements, when combined with archival data, suggest that the radio flux of the star is also variable. An analysis of new and previously published magnetic field observations enabled us to derive a value for the inclination of the rotation axis of i= 12°± 3° and an obliquity of the magnetic axis of β≤ 52°. The nature of the emission variability is similar to that of the prototypical helium-strong star σ Ori E, but since the latter object has an inclination of >75°, δ Ori C provides us with an opportunity to investigate the cool components of the winds and magnetospheres of the helium-strong stars from a different vantage point.
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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 | 0.000 | 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".