Constraints on Inner Disk Evolution Timescales: A Disk Census of the η Chamaeleontis Young Cluster
Bibliographic record
Abstract
We present new L '-band (3.8 μm) observations of stars in the nearby (~97 pc) young (~6 Myr) compact cluster around η Chamaeleontis, obtained with the European Southern Observatory's Very Large Telescope in Paranal, Chile. Our data, combined with J , H , K s photometry from the Two Micron All Sky Survey, reveal that only two of the 12 members surveyed harbor L '-band excesses consistent with optically thick inner disks; both are also likely accretors. Intriguingly, two other stars with possible evidence of ongoing accretion, albeit at very low rates, do not show significant infrared excess: this may imply substantial grain growth and/or partial clearing of the inner disk region, as expected in planet formation scenarios. Our findings suggest that η Cha stars are in an epoch when disks are rapidly evolving, perhaps due to processes related to planet building, and provide further constraints on inner disk lifetimes.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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".