Data from Hubble reveals water vapor in the atmosphere of a Super-Earth planet. K2-18b planet has both water and temperatures that could support life.
K2-18b is eight times the mass of Earth and lies 111 light-years away from us. It is the first exoplanet known to have both water and temperatures favorable for life.
To detect the water vapor, researchers analyzed data caught by NASA/ESA’s Hubble Space Telescope in 2016 and 2017. And then, they ran it through an open-source algorithm they developed to analyze distant planets.
The exoplanet orbits within the habitable zone of an M dwarf, a star smaller than our sun. It is more than eight times the mass of Earth meaning the exoplanet is either an icy giant like Neptune or a rocky world with a thick, hydrogen-rich atmosphere.
The analysis of the starlight passing through the planet’s atmosphere showed hydrogen and helium.
Future studies could determine if other ingredients for life as we know it, like nitrogen and methane, are also present.
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However, K2-18b is also very different from our world. Given the high level of activity of its red dwarf star, the exoplanet may be more hostile than Earth and is likely to be exposed to more radiation.
But scientists need more data to determine what kind of cloud coverage the planet has and how much water is present in the atmosphere.
Temperatures on the planet could be between about -100 degree Fahrenheit (-73 degree Celsius) and 150 Fahrenheit (66 Celsius).
Researchers published their discovery today in Nature Astronomy.
First author, Dr. Angelos Tsiaras (UCL Centre for Space Exochemistry Data (CSED)), said: “Finding water in a potentially habitable world other than Earth is incredibly exciting. K2-18b is not ‘Earth 2.0’ as it is significantly heavier and has a different atmospheric composition. However, it brings us closer to answering the fundamental question: Is the Earth unique?”
Finding water around an exoplanet is really exciting because water is the key ingredient for life as we know it.
Astronomers have found water vapor around exoplanets before, but these worlds have not been very hospitable to life. They’ve been large bodies of gas, similar in size to Jupiter or Neptune.
Co-author Dr. Ingo Waldmann (UCL CSED), said: “With so many new super-Earths expected to be found over the next couple of decades, it is likely that this is the first discovery of many potentially habitable planets. This is not only because super-Earths like K2-18b are the most common planets in our Galaxy, but also because red dwarfs—stars smaller than our Sun—are the most common stars.”
NASA’s Kepler spacecraft discovered K2-18b in 2015.