An in-depth reanalysis of the alleged type Ia supernova progenitor Henize 2-428
Bibliographic record
Abstract
Context. The nucleus of the planetary nebula Hen 2-428 is a short orbital-period (4.2 h), double-lined spectroscopic binary, whosestatus as potential supernova type Ia progenitor has raised some controversy in the literature.Aims. Aiming to resolve this debate, we carried out an in-depth reanalysis of the system.Methods. Our approach combines a refined wavelength calibration, thorough line-identifications, improved radial-velocity measure-ments, non-LTE spectral modeling, as well as multi-band light-curve fitting. Our results are then discussed in view of state-of-the-artstellar evolutionary models.Results. Besides systematic zero-point shifts in the wavelength calibration of the OSIRIS spectra also used in the previous analysis ofthe system, we found that the spectra are contaminated with diffuse interstellar bands. Our Voigt-profile radial velocity fitting method,which considers the additional absorption of these diffuse interstellar bands, reveals significantly lower masses (M1 = 0.66 ± 0.11 Mand M2 = 0.42 ± 0.07 M ) than previously reported and a mass ratio clearly below unity. Our spectral and light curve analyses leadto consistent results, though, we find higher effective temperatures and smaller radii than previously reported. Moreover, we find thered-excess that was reported before, is merely an artifact of an outdated reddening law used in the previous work.Conclusions. Our work showed that blends of He ii λ 5412 Å with DIBs have led to an overestimation of the previously reporteddynamical masses of Hen 2-428. The merging event of Hen 2-428 will not be recognized as a supernova type Ia, but most likely leadto the formation of a H-deficient star. We suggest that the system was formed via a first stable mass transfer episode, followed bycommon envelope evolution, and is now composed of a post-early asymptotic giant branch star and a reheated He-core white dwarf.
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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 | 0.000 | 0.000 |
| 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 | 0.000 |
| 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".