Debris disks as signposts of terrestrial planet formation
Bibliographic record
Abstract
We present models for the formation of terrestrial planets, and the collisional evolution of debris disks, in planetary systems that contain multiple marginally unstable gas giants. We previously showed that in such systems, the dynamics of the giant planets introduces a correlation between the presence of terrestrial planets and cold dust, i.e., debris disks, which is particularly pronounced at λ ~ 70 μm. Here we present new simulations that show that this connection is qualitatively robust to a range of parameters: the mass distribution of the giant planets, the width and mass distribution of the outer planetesimal disk, and the presence of gas in the disk when the giant planets become unstable. We discuss how variations in these parameters affect the evolution. We find that systems with equal-mass giant planets undergo the most violent instabilities, and that these destroy both terrestrial planets and the outer planetesimal disks that produce debris disks. In contrast, systems with low-mass giant planets efficiently produce both terrestrial planets and debris disks. A large fraction of systems with low-mass (M ≲ 30 M⊕) outermost giant planets have final planetary separations that, scaled to the planets’ masses, are as large or larger than the Saturn-Uranus and Uranus-Neptune separations in the solar system. We find that the gaps between these planets are not only dynamically stable to test particles, but are frequently populated by planetesimals. The possibility of planetesimal belts between outer giant planets should be taken into account when interpreting debris disk SEDs. In addition, the presence of ~ Earth-mass “seeds” in outer planetesimal disks causes the disks to radially spread to colder temperatures, and leads to a slow depletion of the outer planetesimal disk from the inside out. We argue that this may explain the very low frequency of >1 Gyr-old solar-type stars with observed 24 μm excesses. Our simulations do not sample the full range of plausible initial conditions for planetary systems. However, among the configurations explored, the best candidates for hosting terrestrial planets at ~1 AU are stars older than 0.1–1 Gyr with bright debris disks at 70 μm but with no currently-known giant planets. These systems combine evidence for the presence of ample rocky building blocks, with giant planet properties that are least likely to undergo destructive dynamical evolution. Thus, we predict two correlations that should be detected by upcoming surveys: an anti-correlation between debris disks and eccentric giant planets and a positive correlation between debris disks and terrestrial planets.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".