Period–luminosity relations for Galactic Type II Cepheids in the Sloan bands
Bibliographic record
Abstract
Context. Type II Cepheids (T2Ceps), alongside RR Lyrae stars, serve as important distance indicators for old Population II stars due to their period–luminosity (PL) relations. However, few studies of these relations in the Sloan photometric system have been conducted. Aims. Our goal is to calibrate PL relations (and their counterparts in Wesenheit magnitudes) in the Sloan–Pan-STARRS gP1rP1iP1 bands for Galactic T2Ceps located in the vicinity of the Sun. Methods. We collected data for 16 T2Ceps of the BL Her-type and 17 of the W Vir-type using 40 cm telescopes of the Las Cumbres Observatory Global Telescope Network. Geometric parallaxes were adopted from Gaia Data Release 3. Results. We have calibrated PL and period–Wesenheit relations for Milky Way BL Her and W Vir stars in the solar neighborhood, as well as for a combined sample of the two types. Conclusions. The relationships derived here will allow the determination of the distances to the T2Ceps that will be discovered by the Legacy Survey of Space and Time survey and, in turn, to probe the extended halo of the Milky Way, as well as the halos of nearby galaxies. To the best of our knowledge, the relations derived in this study are the first for Milky Way T2Ceps in the Sloan bands.
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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 | 0.001 |
| 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 | 0.000 |
| 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 | 0.000 |
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".