Preprint typeset using L ATEX style emulateapj v. 08/13/06 THE SPECTRAL TYPES OF WHITE DWARFS IN MESSIER 4
Bibliographic record
Abstract
mately 10 DB white dwarfs were found in this temperature range (Eisenstein et al. 2006b). While this temperature range is no longer strictly a “gap”, it is still true that the DA/DB ratio is approximately 2.5 times greater at 30 000 K than it is at 20 000 K. This implies that an atmospheric transformation takes place in approximately 10 % of DAs as they cool through this range (Eisenstein et al. 2006b). Below 30 000 K, a helium convection zone is established. Convective velocities can become high enough to overshoot, and mix the helium layer with the hydrogen atmosphere, converting a type DA to a type DB. This occurs in ∼ 25 % of white dwarfs in this temperature range in the field (Hansen and Liebert 2003). For temperatures lower than 6 000 K, the situation becomes even more complicated and uncertain (Bergeron et al. 1997). At these low temperatures the variety of spectral types increases, but in the non-DA gap (6 000– 5 000 K) non-DA white dwarfs have yet to be observed. As white dwarfs cool below 5 000 K, neither hydrogen nor helium lines are excited, and the resultant spectrum is almost featureless, leading to the DC spectral classification. Even more rare are white dwarfs showing metal lines. These are the DQs, for those showing carbon features, and the DZs, for other atomic species. Finally, DP and DH white dwarfs show evidence of having polarized and non-polarized magnetic fields respectively. Prior to the year 2000, the spectra of cluster white dwarfs had been obtained in a piecemeal fashion—only one or two stars would be studied in each cluster, typically by different authors. The Canada-France-Hawaii Telescope (CFHT) Open Star Cluster Survey changed this. The idea behind this survey was to obtain highquality, wide-field images of many open clusters. The rich clusters (i.e., those with well-populated white dwarf cooling sequences) could then be identified, and followed up spectroscopically. Previously, when spectral types were obtained for only several white dwarfs at a time, the absence of a particular spectral type was neither particularly surprising nor interesting. Kalirai et al. (2005) reported 21 spectral identificaarXiv:0909.2254v1
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.003 |
| Bibliometrics | 0.005 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.008 | 0.004 |
| Open science | 0.003 | 0.006 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.810 | 0.790 |
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".