The Invisible Planet in a Carbon Cocoon: How a Hot Neptune Cheated Death express
Planet LTT-9779 b is a hot Neptune, orbiting its star in just 19 hours. Its atmosphere, as revealed by the Webb telescope, is rich in carbon monoxide and carbon dioxide and is 500 times heavier than solar. This dense atmosphere evaporates more slowly, like a thick soup, allowing the planet to survive in the hot Neptune desert. What secrets do these rare worlds hide?
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.