A Confirmation of the Optical Spectroscopy Approach: Discovery of Two More Pulsating DA (ZZ Ceti) White Dwarfs
Bibliographic record
Abstract
We first review and rebut the arguments that have been put forward recently against the use of optical spectroscopy in the determinations of the atmospheric parameters of ZZ Ceti and neighboring stars in the log g - T eff diagram. We reiterate instead the conclusion of Bergeron et al. that optical spectroscopy alone , when properly handled and modeled, leads to very accurate and reliable estimates of the surface gravities and effective temperatures of ZZ Ceti pulsators. The optical spectroscopy approach has had a yield of 100% so far in predicting the variability of candidate ZZ Ceti stars, and we present evidence here of its successful application to two more objects. We hence report the detection of multiperiodic luminosity variations in the light curves of two DA white dwarfs, MCT 0145-2211 and HE 0532-5605, selected on the basis of an analysis of their optical spectra. This brings the number of known ZZ Ceti stars to a total of 34. Our study reveals that MCT 0145-2211 has T eff = 11,550 K and log g = 8.14, while HE 0532-5605 has T eff = 11,560 K and log g = 8.49, which places them both inside the empirical instability strip uncovered by Bergeron et al. We find that the amplitudes, periods, and degree of complexity of the light curves are consistent with the positions of the stars rather near the red edge. Using the same homogeneous approach, we have, so far, analyzed high-quality optical spectra for some 103 nonvariable DA white dwarfs and all of the 34 known ZZ Ceti stars. The picture of the empirical instability strip that emerges is that of a pure strip, in which no nonvariable stars are found. It has a trapezoidal shape in the log g - T eff plane, with the blue edge showing a stronger dependence on the surface gravity than the red edge does.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".