CLOUDS AND CHEMISTRY IN THE ATMOSPHERE OF EXTRASOLAR PLANET HR8799b
Bibliographic record
Abstract
Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H - and K -band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrowband photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near-IR spectrum. Strong water absorption is detected, indicating a hydrogen-rich atmosphere. Only weak CH 4 absorption is detected at K band, indicating efficient vertical mixing and a disequilibrium CO/CH 4 ratio at photospheric depths. The H -band spectrum has a distinct triangular shape consistent with low surface gravity. New giant planet atmosphere models are compared to these data with best-fitting bulk parameters, T eff = 1100 K ±100 and log ( g ) = 3.5 ± 0.5 (for solar composition). Given the observed luminosity (log L obs / L ☉ ∼ − 5.1), these values correspond to a radius of 0.75 R Jup +0.17 − 0.12 and a mass of ∼0.72 M Jup +2.6 − 0.6 —strikingly inconsistent with interior/evolution models. Enhanced metallicity (up to ∼10 × that of the Sun) along with thick clouds and non-equilibrium chemistry are likely required to reproduce the complete ensemble of spectroscopic and photometric data and the low effective temperatures (<1000 K) required by the evolution models.
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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 | 0.000 | 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) | 0.001 | 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".