The Invisible Planet in a Carbon Cocoon: How a Hot Neptune Cheated Death ⚡ экспресс
LTT-9779 b is an ultra-hot Neptune (Rp≈4.7 R⊕, Mp≈29 M⊕, P=19 h) in the hot Neptune desert. JWST/NIRSpec G395H phase curve observations in the near-IR (penetrating through high-altitude clouds known from NIRISS/SOSS) revealed: CO and CO2 dominate at all phases with volume mixing ratios of ~10⁻¹ and ~10⁻⁴, indicating a globally mixed carbon reservoir. H2O is weaker, with tentative SO2 (a photochemistry product). C/O ratio ≈1, metallicity >500 times solar, consistent with equilibrium chemistry of hot atmospheres. High metallicity increases molecular weight and reduces dissipation, helping the planet retain its envelope in the evaporation zone. This is a rare opportunity to study atmospheric survival and chemistry under extreme conditions.
Astronomers couldn't understand why the 'hot Neptune desert' — a region right next to stars — has almost no Neptune-sized planets. It was thought that there they are doomed: the star's proximity boils off the atmosphere, leaving a bare rocky core. But the exoplanet LTT-9779 b, 29 times heavier than Earth and with a 19-hour orbit, survived. The James Webb Space Telescope peered into its heat-blasted world.
Using spectral analysis and transit observations across the star's disk, scientists discovered that the atmosphere is packed with carbon — carbon monoxide and carbon dioxide. There is tens of thousands of times more of these than water vapor. The carbon-to-oxygen ratio is nearly one, and heavy elements are 500 times more abundant than in the Sun. This mixture prevents the planet from evaporating: heavy molecules, like cocoon threads, firmly hold the gas envelope. Meanwhile, LTT-9779 b reflects 80% of light — it's the shiniest known exoplanet, a giant mirror in space. David Charbonneau, pioneer of the transit method, never imagined planets could be this cunning.
🎯 The dayside of LTT-9779 b is baked to 2000°C — that's as hot as an electric stove's coil glowing red-hot.