Thanks to the magnificent Hubble Space Telescope, we got a good look at the make-up of the atmosphere of a rocky planet outside the solar system last week, with a size and density similar to that of Earth. It’s far from a habitable paradise, so don’t get too excited, but it’s a notable breakthrough and a prelude to even more interesting results.
The work was accepted for publication in the Astronomical Journal and is the result of a collaboration between American, British and Brazilian researchers. On the national side, Adriana Valio from the Universidade Presbiteriana Mackenzie in São Paulo and Raissa Estrela, currently a postdoc at JPL, the NASA Jet Propulsion Laboratory in the USA, took part.
The destination was the planet GJ 1132 b, which is 41 light years away from here. It orbits a red dwarf, a star much smaller than the Sun, and does one lap in just 38 hours. That is, it is close to its star king. As a result, it receives 19 times more stellar radiation than Earth from the sun. Nobody expects to find life there.
However, there are reasons to delight in the discovery, which predicts what to expect on planets around red dwarfs. For decades, astronomers were suspicious that the high levels of turbulence in these tiny stars were preventing a world from maintaining an atmosphere. Here is a planet that we have known since 2017 to have a gaseous shell.
With a diameter of 16% and a mass 66% larger than terrestrial, GJ 1132 b is clearly rocky and slightly denser than Earth. By observing the star’s light scraping through its atmosphere before reaching Earth, Hubble obtained a spectrum (the decomposition of light) that carried the signature of the gases it encountered along the way.
Now we know that the planet’s atmosphere contains hydrogen, hydrogen cyanide, and methane, as well as aerosols similar to what we see in Titan’s air, Saturn’s largest moon. The scientists’ hypothesis is that GJ 1132 b was originally a mininetuno with a huge primordial atmosphere of hydrogen and helium. This would have been carried away by the stellar wind a long time ago. But then, thanks to volcanic activity, the planet gained a second atmosphere – the one we see now.
Hubble’s detection is at the limit of the space telescope’s instruments, but researchers hope the James Webb Space Telescope, due to be launched next October, can more easily confirm the results. And also take a look at the atmosphere of many other rocky exoplanets, some of which are in the habitable zones of their systems – neither too hot nor too cold around the star, where living conditions could exist on the surface of a world there. It is to be concerned about what’s coming.
This column is published in Folha Corrida on Mondays.
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