Asteroseismology of the Crystallized ZZ Ceti Star BPM 37093: A Different View
Bibliographic record
Abstract
BPM 37093 is a pulsating white dwarf of the ZZ Ceti type massive enough to have undergone partial crystallization. Metcalfe et al. recently claimed to have measured the fraction of crystallized matter in that star on the basis of asteroseismological techniques and determined a value upward of 90%. If true, this is a most significant achievement, well worthy of further scrutiny. In this spirit, we have reexamined the data available—eight periods—with our own independent model-building code and period-matching code in parameter space. In contrast to the above authors, we find that the likely value of the fraction of solidified matter in BPM 37093 is substantially less than 90%, but also that we cannot pin it down with any reasonable accuracy. Our results instead suggest that the value probably lies between 32% and 82%, depending on the unknown chemical composition of the core. We stress that, in principle, asteroseismology can be used to derive the fundamental parameters of BPM 37093, possibly including its core composition, but that, in this specific case, the information contained in the current period data appears insufficient. Indeed, we find full families of different models in parameter space that provide equally valid matches to the available period data. We suggest that the "lack of information" that appears to characterize the set of eight observed periods in BPM 37093 is related to the fact that these periods all correspond to high-order modes reaching into the asymptotic regime ( k ≫ 1). We also point out that asteroseismology cannot provide a direct test of crystallization theory; the crystallized mass fraction is merely a secondary quantity derived by fixing the interior equation of state of the models and using the inferred fundamental parameters (including the core composition).
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".