Since the first discovery of a planet outside our solar system in 1995 by Michel Mayor and Didier Queloz (recipients of the 2019 Nobel Prize in Physics for this feat), the number of exoplanets detected has continued to grow. Today, there are more than 6,000 of them, but there is always this perpetual question: on how many of them does life exist?
One thing is certain: for life to arise, the quantity of X-ray radiation emitted by the central star must not be too great. On this basis, researchers isolated 57 suns and attempted to observe whether or not their X-ray emission could be deleterious.
The European Extremely Large Telescope could prioritize the exoplanets found in this study. © Swinburne Astronomy Productions/ESO
Isolate the most protected
To achieve this, astrophysicists used data collected by the Chandra space telescopes of the American NASA and XMM-Newton of the European Esa, both designed for the observation of X-rays in space. Considering life as we know it thanks to our accumulated knowledge on Earth, they deduced in each case whether the said observed X-radiation was compatible or not with the emergence of life. They then isolated stars for which planets located in the habitable zone experience X-ray radiation similar to or lower than that experienced by the Earth in its early days.
Their conclusion does not say that around these stars a planet shelters life at a minimum. She explains that, even if it means wanting to flush it out, we might as well turn our efforts in that direction. As such, future giant telescopes, such as the European Extremely Large Telescope currently built in northern Chile, could be used to study the atmosphere and surface composition of these exoplanets.