Variable stars in Local Group galaxies
Bibliographic record
Abstract
Aims. Pulsating variable stars are invaluable tracers for reconstructing the star formation history and chemical evolution of their host galaxies. In this work, we explore the variable star population of Leo II, a distant dwarf spheroidal satellite of the Milky Way. Methods. We analyse an extensive dataset of ground-based B V R I time-series photometry spanning over 35 years. By examining the properties of RR Lyrae stars, we constrain the early chemical enrichment and spatial variation within Leo II. Additionally, we investigate the anomalous Cepheids in order to connect their characteristics with the galaxy’s prolonged star formation history, as revealed by deep HST/WFC3 colour–magnitude diagrams. Results. We identified and characterised 175 variable stars, with all but one associated with Leo II. Our work includes the discovery of 25 new RR Lyrae stars and two new anomalous Cepheids. Moreover, we reclassified V88 as a BL Her variable star. By employing multiple independent methods, including metallicity-luminosity relations for RR Lyrae stars and period–luminosity and period–Wesenheit relations for both RR Lyrae and anomalous Cepheids, we derived a true distance modulus of ( m − M ) 0 = 21.60 ± 0.03 mag, corresponding to 209 ± 4 kpc. Furthermore, we discuss potential formation scenarios for anomalous Cepheids and suggest that, despite the extended star formation history, they are all compatible having originated from old binary stars, with no contribution from young, evolved single stars.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".