Bibliographic record
Abstract
In an attempt to explain faster than average rotation of Be stars, a model for rotational evolution of a pre-main sequence (PMS) star with a weak primordial magnetic field was applied to stars with masses between 3 and 7 solar mass. The model takes into account the accretion of matter along the magnetic field lines, the stellar field-disk interaction and a magnetized wind. Evolutionary changes of the stellar moment of inertia are also included. The stellar mass and magnetic flux were assumed constant during the PMS evolution. The results indicate that magnetic accretion spins up a star early in its PMS life and if the star has a short PMS life time (i.e. high enough mass), it may keep faster rotation until the zero age main sequence (ZAMS). Detailed calculations show that typically a factor of two faster rotation is achieved compared to the conserved angular momentum case. This requires an intense accretion going on for a substantial fraction of the PMS phase in the presence of a surface magnetic field not exceeding 400 G. Stronger fields slow down the stellar rotation very efficiently by the magnetic field-disk locking mechanism. Low mass stars with PMS life time significantly longer than the time scale of spin down by the magnetic wind may be efficiently braked by the wind operating after the disappearance of the disk. They can retain faster than average rotation only under very special conditions. It is postulated that ZAMS progenitors of Be stars possess fossil magnetic fields with surface intensity between 40 and 400 G. The fields result in rotation rates about two times higher than those of normal stars in full agreement with the observations. If the observed Be stars have already evolved from ZAMS, their present magnetic fields should be correspondingly weaker due to the evolutionary increase of the stellar radius. ZAMS stars with magnetic fields weaker than about 40 G should have normal rotation and those with fields significantly stronger than 400 G should become slowly rotating Ap-Bp magnetic stars. The case of β Cephei, with its present surface magnetic field close to 400 G, is a special case of an intermediate field, strong enough to slow down the star's rotation in the PMS phase but apparently not strong enough to develop Bp star characteristics.
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 | 0.000 | 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) | 0.001 | 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".