Magnetic models of slowly rotating magnetic Ap stars: aligned magnetic and rotation axes
Bibliographic record
Abstract
As a result of major surveys carried out during the past decade by Mathys and collaborators, we now have mea- surements with full phase coverage of several magnetic field moments, including the mean longitudinal field B', the mean field modulus Bs, and in most cases the mean quadratic field Bmq and mean crossover field Bxover, for a sample of 24 chem- ically peculiar magnetic (Ap) stars. This represents an increase of a factor of order five in the stellar sample with data of this quality, compared to the situation a decade ago. We exploit this dataset to derive general and statistical prop- erties of the stars in the sample, as follows. First, we fit the avail- able field moment observations assuming a simple, axisymmet- ric multipole magnetic field expansion (with dipole, quadrupole, and octupole components) over each stellar surface. We show that this representation, though not exact, gives an adequate description of the available data for all the stars in this sam- ple, although the fit parameters are in many cases not unique. We find that many of the stars require an important quadrupole and/or octupole field component to satisfy the observations, and that some (usually small) deviations from our assumed axisym- metric field distributions are certainly present. We examine the inclination i (0 i 90) of the rotation axis to the line of sight and the obliquity (0 90) of the magnetic field with respect to the rotation axis, and show that the stars with periods of the order of a month or longer have systematically small values of : slowly rotating magnetic stars generally have their magnetic and rotation axes aligned to within about 20 , unlike the short period magnetic Ap stars, in which is usually large. This is a qualitatively new result, and one which is very important for efforts to understand the evolution of magnetic fields and angular momentum in the magnetic Ap stars.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".