Updated Mass, Eccentricity, and Tidal Heating Constraints for the Earth-sized Planet LP 791-18 d
Bibliographic record
Abstract
Abstract LP 791-18 d is a temperate Earth-sized planet (R P = 1.03 R ⊕, P = 2.76 days) orbiting a late M dwarf, with an interior super-Earth (LP 791-18 b, R P = 1.2 R ⊕, P = 0.95 days) and an exterior sub-Neptune (LP 791-18 c, R P = 2.5 R ⊕, P = 4.99 days). Dynamical interactions between LP 791-18 d and c produce transit timing variations (TTVs) that can be used to constrain the planet masses and eccentricities. These interactions can also force a non-zero eccentricity for LP 791-18 d, which raises its internal temperature through tidal heating and could drive volcanic outgassing. We present three new transit observations of LP 791-18 c with Palomar/WIRC, including the most precise TTV measurements (<6 s uncertainty) of this planet to date. We fit these times with a TTV model to obtain updated constraints on the mass, eccentricity, and tidal heat flux of LP 791-18 d. We reduce the mass uncertainty by more than a factor of two (M d = 0.91 ±0.19 M ⊕). We perform an updated fit assuming tidally damped free eccentricities and find e d = 0.001 1 − 0.0008 + 0.0010 and e c = 0.0001 ± 0.0001, consistent with circular orbits. We find that the observed TTVs are not sensitive to e ≤ ∼0.01. Without a tidally damped eccentricity prior, e d = 0.05 6 − 0.014 + 0.015 , much higher than the eccentricity predicted by n-body simulations incorporating the effects of dynamical excitation and tidal damping. We predict the timing offset relative to the prediction for a circular orbit of upcoming JWST secondary eclipse observations for LP 791-18 d ( Δ t = − 0 . 2 − 2.7 + 2.0 minutes and Δ t = − 11 7 − 47 + 41 minutes for the damped and undamped eccentricity cases, respectively), which could tightly constrain the eccentricity and tidal quality factor of this Earth-sized exoplanet.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".