Revisiting RV Tauri stars: first ionization potential (FIP) effect
Bibliographic record
Abstract
We have derived elemental abundances of eight RV Tauri-type post-asymptotic giant branch stars: AR Sgr, CE Vir, DY Aql, HP Lyr, SS Gem, SZ Mon, TT Oph, and UZ Oph. The abundance analysis of these luminous stars is based on the high-resolution (R ≈ 55 000) optical echelle spectra obtained with the 2.1 m Struve reflector telescope and the CCD-equipped Sandiford Cassegrain echelle spectrograph at the McDonald Observatory. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters and elemental abundances for 17 species including C, Na, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, and Nd. Then, the computed up-to-date abundances are used to investigate FIP in the program stars, as seen in the Sun and sun-like stars. Also, we scrutinize their behavior for dust–gas separation as an alternative mechanism to the FIP. For the first time, we provide atomic line lists with up-to-date atomic data employed in the analysis for AR Sgr, HP Lyr, SZ Mon, TT Oph, and UZ Oph.
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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 | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".