In a key development in space research, astronomers have discovered water vapour in the atmosphere of a distant exoplanet called K2-18b for the first time. According to researchers at the Center for Space Exochemistry Data (CSED) at the University College London (UCL), K2-18b, which has a mass eight times greater than that of the Earth, is orbiting a small red dwarf star about 110 light-years away in the constellation Leo.
The exoplanet was discovered by NASA’s Kepler Space Telescope in 2015. According to scientists, the latest development is the first-ever successful detection of the atmosphere for an exoplanet which is orbiting in its star’s “habitable zone,” a distance where water could be available in the form of liquid.
Given its larger mass, the surface gravity of K2-18b exoplanet is much higher than that of the Earth. Also, the high level of activity of its red dwarf star, the planet may be more hostile than Earth and is likely to be exposed to more radiation.
According to the findings of the research that was recently published in Nature Astronomy, using the archive data from 2016 and 2017 captured by the NASA/ESA Hubble Space Telescope, scientists developed open-source algorithms to analyse the starlight filtered through K2-18b’s atmosphere. The results showed the molecular signature of water vapour and also indicated the presence of hydrogen and helium in the atmosphere of K2-18b.
“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?” Dr. Angelos Tsiaras, the first author of the research from CSED said in a statement.
The researchers also believe that other molecules including nitrogen and methane may be present in K2-18b but, with current observations, they remain undetectable. Further studies in this regard are necessary for estimating the cloud coverage and the percentage of water that is present in the atmosphere.
“This study contributes to our understanding of habitable worlds beyond our Solar System and marks a new era in exoplanet research, crucial to ultimately placing the Earth, our only home, into the greater picture of the Cosmos,” Tsiaras said.
The K2-18b is one of the hundreds of “super-Earths” discovered by the Kepler Space Telescope. According to NASA, its TESS mission is expected to detect hundreds of more super-Earths in the coming years. The next generation of space telescopes, including the James Webb Space Telescope, will be able to characterize exoplanet atmospheres in more detail.