New study details atmosphere on ‘hot Neptune’ 260 light years away that ‘shouldn’t exist’ (University of Kansas). Never tell a planet it shouldn’t exist if it does exist. That’s a bad reflection on the assumptions of the astronomers. The exoplanet has no obligation to conform to expectations.
The findings concerning the recently found planet LTT9779b were published today in Astrophysical JournalLetters. The paper details the very first spectral atmospheric characterization of any planet discovered by TESS, the first global temperature map of any TESS planet with an atmosphere and a hot Neptune whose emission spectrum is fundamentally different from the many larger “hot Jupiters” previously studied.
“For the first time, we measured the light coming from this planet that shouldn’t exist,” said Ian Crossfield, assistant professor of physics & astronomy at KU and lead author of the paper. “This planet is so intensely irradiated by its star that its temperature is over 3,000 degrees Fahrenheit and its atmosphere could have evaporated entirely. Yet, our Spitzer observations show us its atmosphere via the infrared light the planet emits.”
From spectra at occultation, the planet hunters were able to make
“We think this is because hot Neptunes aren’t massive enough to avoid substantial atmospheric evaporation and mass loss,” he said. “So, most close-in hot exoplanets are either the massive hot Jupiters or rocky planets that have long ago lost most of their atmospheres.”
Q: How is this planet able to retain its atmosphere?”