Water vapor has been detected for the first time in the atmosphere of a super-earth with temperatures suitable for life.
A UK scientific team studied the planet K2-18b, which is eight times the mass of Earth and is 110 light-years distant.
Researchers at University College London have discovered evidence of atmospheric water vapor in K2-18b located within the habitable zone of its star.
The exoplanet K2-18b
K2-18b, is so far the only planet that orbits a star outside the solar system with the potential to be inhabited by the conditions of water and temperatures.
According to Angelos Tsiaras, first author of the work, “finding water in a potentially habitable world other than our own is very exciting. Exoplanet K2-18b would not be an 'Earth 2.0' as it is significantly heavier and has a different atmospheric composition. However, it brings us closer to the answer to the fundamental question: Is the Earth unique?“.
The team of researchers used data provided by the Hubb Space Telescopele from ESA / NASA and developed open source algorithms to analyze starlight filtered through the atmosphere of K2-18b. The results have revealed the molecular signature of water vapor and the presence of hydrogen and helium in the planet's atmosphere.
The team of researchers also speculates on the presence of other molecules, including nitrogen and methane, but they are still undetectable with current instruments. Therefore, they say, “additional studies are required to estimate cloud cover and the percentage of atmospheric water present”.
The planet orbits the cold dwarf star K2-18, which is about 110 light-years from Earth in the constellation Leo. Given the high level of activity of its red dwarf star, K2-18b may be more hostile than Earth and is likely to be exposed to more radiation.
Giovanna Tinetti, co-author and principal investigator of ESA's ARIEL mission, indicates that her team's finding “Makes the K2-18 b one of the most interesting targets for future study. More than 4,000 exoplanets have been detected, but we don't know much about their composition and nature. By observing a large sample of planets, we can reveal secrets about their chemistry, formation and evolution "
For Tsiaras, the new study "It will help improve understanding of habitable worlds beyond the solar system and mark a new era in exoplanet research".
The research has been funded by the European Research Council and the UK Science and Technology Facilities Council.
Angelos Tsiaras, Ingo Waldmann, Giovanna Tinetti. Jonathan Tennyson and Sergey N. Yurchenko. "Water vapor in the atmosphere of the habitable-zone eight-Earth-mass planet K2-18 b". Nature Astronomy(September, 2019).
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