A spectroscopic test of the rotational modulation origin of periodic Kepler photometric variability of A-type stars
Bibliographic record
Abstract
ABSTRACT High-precision space-based photometry obtained by the Kepler and TESS missions has revealed evidence of rotational modulation associated with main-sequence (MS) A- and late B-type stars. Generally, such variability in these objects is attributed to inhomogeneous surface structures (e.g. chemical spots), which are typically linked to strong magnetic fields ($B\gtrsim 100\, {\rm G}$) visible at the surface. It has been reported that ≈44 per cent of all A-type stars observed during the Kepler mission exhibit rotationally modulated light curves. This is surprising considering that ≲10 per cent of all MS A-type stars are known to be strongly magnetic (i.e. they are Ap/Bp stars). We present a spectroscopic monitoring survey of 44 A- and late B-type stars reported to exhibit rotational modulation in their Kepler light curves. The primary goal of this survey is to test the hypothesis that the variability is rotational modulation by comparing each star’s rotational broadening (vsin i) with the equatorial velocities (veq) inferred from the photometric periods. We searched for chemical peculiarities and binary companions in order to provide insight into the origin of the apparent rotational modulation. We find that 14 stars in our sample have vsin i > veq and/or have low-mass companions that may contribute to or be responsible for the observed variability. Our results suggest that more than 10 per cent of all MS A- and late B-type stars may exhibit inhomogeneous surface structures; however, the incidence rate is likely ≲30 per cent.
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 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".