An exoplanet located 73 light-years away is defying astronomers' expectations. TOI-270 d, far from being an ocean world, appears to be a scorching super-Earth enveloped in a dense atmosphere.
Observations from the James Webb Space Telescope have revealed the presence of carbon dioxide, methane, and water vapor in TOI-270 d's atmosphere. These findings, published in
The Astrophysical Journal, challenge the Hycean planet hypothesis, instead suggesting a super-Earth model with a surface magma ocean.
The team led by Dr. Christopher Glein used geochemical tools to model TOI-270 d's atmosphere. Their model explains the surprising absence of ammonia, suggesting it's either absorbed by a magma ocean or converted into nitrogen gas due to extreme temperatures.
This study marks a turning point in understanding sub-Neptune exoplanets. Researchers applied methods developed for our Solar System to a distant world, paving the way for new discoveries about planet formation and evolution.
TOI-270 d's data provides unique insights into planetary atmospheric diversity. Contrary to expectations, this planet doesn't have conditions suitable for life as we know it, but it enriches our understanding of extraterrestrial geochemical processes.
A SwRI-led study modeled the chemistry of TOI-270 d, an exoplanet sized between Earth and Neptune, revealing it's a giant rocky planet (super-Earth) surrounded by a thick, hot atmosphere.
NASA's JWST detected gases from an atmospheric region hotter than 700°F (370°C), exceeding Venus' surface temperature. The model illustrates a possible magma ocean removing ammonia from the atmosphere. Hot gases then undergo equilibration and are propelled into the planet's photosphere where JWST can detect them.
Credit: Southwest Research Institute
Future research will focus on analyzing other exoplanets to understand planetary environment diversity. TOI-270 d is just one example of the many surprises the Universe still holds.
What is a super-Earth?
A super-Earth is an exoplanet with mass between Earth's and Neptune's. These planets can be rocky like Earth or possess thick atmospheres like TOI-270 d.
Super-Earths particularly interest astronomers as they might harbor life-friendly conditions. However, as TOI-270 d demonstrates, some are too hot to be habitable.
Studying these planets helps better understand planetary system diversity. TOI-270 d, with its dense atmosphere and extreme temperatures, exemplifies the varied configurations super-Earths can take.