Systematic Identification of g-Mode Pulsations in Subdwarf B Stars for Kepler Data
Bibliographic record
Abstract
The Kepler and TESS space missions have revealed the g-mode pulsation spectra of many sdB stars, showing complex behaviors, with some stars exhibiting trapped modes interposed in the asymptotic period sequences of regular period spacing, while others do not. We used the STELUM (STELlar modeling at the Université de Montréal) to compute static and evolutionary models of sdB stars with different prescriptions for their chemical and thermal structures, and our PULSE code to compute their associated theoretical spectra from degrees l=1 to l=4 and for periods between 1000s and 15000s, thus covering the range of observed g-modes in such stars. Our results show that the structure of g- modes spectra, and notably the appearance of trapped modes, are dependent on the chemical and thermal structures of the models, and in particular on the region above the He-burning core. We mainly observe three flavors of spectra for mid to high radial orders g-modes: ”flat” spectra of nearly constant period spacing, spectra with regular mode trapping, and spectra of ”wavy” patterns in period spacing. In the two later types of spectra, we identified the region where modes are trapped in the star. The next natural step is comparing observed g-mode spectra to our theoretical models to constrain by asteroseismology the internal structure of sdB stars, and in particular the region above the He-burning core. This starts by extracting and analyzing the g-modes frequencies from available observations, which reach hundreds of frequencies in Kepler datasets, including rotational multiplets and frequency modulation effects. Given this large number of frequencies, and rotational multiplets generally being present for only a minority of them, identifying the degree of each frequency, and thus the pulsation spectra associated to a star, is complex and often includes an arbitrary component, especially in the case of stars presenting mode trapping. We thus aim at making mode identification a systematic process for slow rotating sdB pulsators, through a genetic algorithm currently in development. The latter takes advantages of continuous sequences of l=1 and l=2 modes found in Kepler data for sdB stars, overlapping properties between degrees, and offsets in periods induced by mode trapping, to infer the most likely degree for a given frequency.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".