The Clusters Ages Experiment (CASE). I. V209 ω Cen: An Eclipsing Post-Common-Envelope Binary in the Globular Cluster ω Cen
Bibliographic record
Abstract
We use photometric and spectroscopic observations of the detached eclipsing binary V209 ω Cen to derive the masses, radii, and luminosities of the component stars. The system exhibits total eclipses and, based on the measured systemic velocity and the derived distance, is a member of the globular cluster ω Cen. We obtain 0.945 ± 0.043 M ⊙ , 0.983 ± 0.015 R ⊙ , and 6.68 ± 0.88 L ⊙ for the cooler but larger and more luminous primary component. The secondary component has 0.144 ± 0.008 M ⊙ , 0.425 ± 0.008 R ⊙ , and 2.26 ± 0.28 L ⊙ . The effective temperatures are estimated at 9370 K for the primary and at 10,866 K for the secondary. On the color-magnitude diagram of the cluster, the primary component occupies a position between the tip of the blue straggler region and the extended horizontal branch, while the secondary component is located close to the red border of the area occupied by hot subdwarfs. However, its radius is too large and its effective temperature is too low for it to be an sdB star. We propose a scenario leading to the formation of a system with such unusual properties, with the primary component "reborn" from a former white dwarf that accreted a new envelope through mass transfer from its companion. The secondary star has lost most of its envelope while starting its ascent onto the subgiant branch. It failed to ignite helium in its core and is currently powered by a hydrogen-burning shell.
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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 | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.014 | 0.004 |
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".