Dispersal timescale of protoplanetary disks in the low-metallicity young cluster Dolidze 25
Bibliographic record
Abstract
<jats:p><jats:italic>Context.</jats:italic> The dispersal of protoplanetary disks sets the timescale that is available for planets to assemble, and thus it is one of the fundamental parameters in theories of planetary formation. Disk dispersal is determined by several properties of the central star, the disk itself, and the surrounding environment. In particular, the metallicity of disks may affect their evolution, but controversial results have been published so far: disks in low-metallicity clusters appear to disperse rapidly, while some evidence supports the existence of accreting disks that are several million years old in the Magellanic Clouds.</jats:p> <jats:p><jats:italic>Aims.</jats:italic> We study the dispersal timescale of disks in Dolidze 25, the young cluster in the proximity of the Sun with the lowest metallicity, to understand whether disk evolution is affected by the low metallicity of the cluster.</jats:p> <jats:p><jats:italic>Methods.</jats:italic> We analyzed <jats:italic>C</jats:italic><jats:italic>h</jats:italic><jats:italic>a</jats:italic><jats:italic>n</jats:italic><jats:italic>d</jats:italic><jats:italic>r</jats:italic><jats:italic>a</jats:italic> ACIS-I observations of the cluster and combined the resulting source catalog with existing optical and infrared catalogs of the region. We selected the disk-bearing population in a circular region with a diameter of 1° centered on Dolidze 25 from criteria based on infrared colors, and we selected the disk-less population within a smaller central region from the X-ray sources with O infrared counterparts. In both cases, criteria were applied to discard contaminating sources in the foreground or background. We derived stellar parameters from isochrones that were fit to color-magnitude diagrams.</jats:p> <jats:p><jats:italic>Results.</jats:italic> We derived a disk fraction of ∼34% and a median age of the cluster of 1.2 Myr. To minimize the effect of incompleteness and spatial inhomogeneity in the list of members, we restricted this calculation to stars in a magnitude range within which our selection of cluster members is fairly complete. We also adopted different cuts in stellar masses. When we compare this estimate with existing estimates of the disk fraction of clusters younger than 10 Myr, the disk fraction of Dolidze 25 appears to be lower than what is expected based on its age alone.</jats:p> <jats:p><jats:italic>Conclusions.</jats:italic> Even though our results are not conclusive given the intrinsic uncertainty on stellar ages estimated from isochrone fitting to color-magnitude diagrams, we suggest that disk evolution in Dolidze 25 may be affected by the environment. Given the poor O-star population and low stellar density of the cluster, it is more likely that the disk dispersal timescale is dictated more by the low metallicity of the cluster than by external photoevaporation or dynamical encounters.</jats:p>
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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 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".