Can we live on distant planets? NYU Abu Dhabi study determines habitability

Scientists have been trying to find signs of life on exoplanets – planets outside our solar system – for nearly two decades

This artist's impression shows a dramatic close-up of the scorched extrasolar planet HD 209458b in its orbit 'only' 7 million kilometres from its yellow Sun-like star. The planet is a type of extrasolar planet known as a 'hot Jupiter'. Using the NASA/ESA Hubble Space Telescope, for the first time, astronomers have observed the atmosphere of an extrasolar planet evaporating off into space (shown in blue in this illustration). Much of this planet may eventually disappear, leaving only a dense core. Astronomers estimate the amount of hydrogen gas escaping HD 209458b to be at least 10 000 tonnes per second, but possibly much more. The planet may therefore already have lost quite a lot of its mass.
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Researchers in Abu Dhabi are studying how a planet's relationship with its host star can affect its ability to support life.

A new study by NYU Abu Dhabi found that emissions from host stars can strip away the atmosphere of planets orbiting them. Scientists believe that planets with no atmosphere are uninhabitable.

Results of the study were published in the Monthly Notices of Royal Astronomical Society: Letters journal this month and led by research scientist Dr Dimitra Atri with involvement from graduate student Shane Carberry Mogan.

After looking at 493 host stars outside our solar system, it was found that extreme ultraviolet radiation and stellar flares from some categories of host stars can destroy the upper atmosphere of planets orbiting them.

"We have identified exoplanets in the M0 to M4 [host stars] category are least likely to be habitable, because their atmospheres will be completely eroded by extreme ultraviolet radiation," Dr Atri told The National.

So far, scientists have discovered 4,000 planets around more than 3,000 host stars, none of which have shown habitable conditions similar to Earth's.

To find distant planets that can support life, researchers look at planets in habitable zones known as the Goldilocks Zone. This is a zone where planets are not too close or too far from their host star, allowing it to sustain water.

For example, Earth is far enough from its host star, the Sun, to avoid radiation, yet close enough to stay warm.

“Given the close proximity of exoplanets to host stars, it is vital to understand how space weather events tied to those stars can affect the habitability of the exoplanet,” Dr Atri said.

His study showed that lighter stars that get less excessive radiation have more chances of having habitable planets orbiting them.

The findings could help scientists take a host star’s radiation levels into account when trying to determine an exoplanet’s ability to support life.

Dr Atri used data from Nasa’s Transiting Exoplanet Survey Satellite observatory for his study.

“The next research step would be to expand our data set to analyse stellar flares from a larger variety of stars to see the long-term effects of stellar activity, and to identify more potentially habitable exoplanets,” he said.

Dr Atri also hopes to use data from UAE’s Emirates Mars Mission to analyse how the Red Planet lost most of its atmosphere.

Scientists believe the planet once supported ancient life.

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