Chemodynamical properties of the Anticentre Stream: a surviving disc fossil from a past satellite interaction
Bibliographic record
Abstract
ABSTRACT Using Gaia second data release (DR2), we trace the Anticentre Stream (ACS) in various stellar populations across the sky and find that it is kinematically and spatially decoupled from the Monoceros Ring. Using stars from lamost and segue, we show that the ACS is systematically more metal-poor than Monoceros by 0.1 dex with indications of a narrower metallicity spread. Furthermore, the ACS is predominantly populated of old stars ($\sim 10\, \rm {Gyr}$), whereas Monoceros has a pronounced tail of younger stars ($6-10\, \rm {Gyr}$) as revealed by their cumulative age distributions. Put together, all of this evidence support predictions from simulations of the interaction of the Sagittarius dwarf with the Milky Way, which argue that the ACS is the remains of a tidal tail of the Galaxy excited during Sgr’s first pericentric passage after it crossed the virial radius, whereas Monoceros consists of the composite stellar populations excited during the more extended phases of the interaction. Importantly, the ACS can be viewed as a stand-alone fossil of the chemical enrichment history of the Galactic disc.
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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 | 0.001 |
| 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".