One of the seven rocky planets orbiting the TRAPPIST-1 red dwarf star likely hosts an Earth-like ocean world, claims new research by a team of astronomers, who used updated climate models to analyse the planetary system in detail.
TRAPPIST-1 is an 'M dwarf ' star located about 39 light years from Earth. It sits in the Aquarius constellation and is cooler and smaller than the Sun. The star's planetary system consists of seven planets, roughly the size of the Earth, with three being near its habitable zone.
When the system was first discovered, it was thought that some of these planets might have potentially habitable worlds.
Later studies suggested that the host star (a red dwarf, which are usually more active than Sun-like stars) would have probably burned off any atmosphere on these planets.
However, the new study offers a marginally more optimistic scenario, suggesting that the planet known as TRAPPIST-1e may have an ocean on its surface.
The study led by researchers from the University of Washington simulated the environmental states for each planet in the system by combing terrestrial climate models with photochemistry models. The team investigated the evolution of the TRAPPIST-1 system by modelling the radiation and light coming off the host star and analysing their impact on the atmospheres of each planets.
The results suggested that TRAPPIST-1b, the closest planet to the star, would be a completely inhospitable world.
TRAPPIST-1c and d are also unlikely to host life. These planets would be somewhat more temperate compared to TRAPPIST-1b, but are likely to have a dense, uninhabitable atmosphere.
TRAPPIST-1e, the fourth-most distant planet from the host star, sits at perfect spot and could still have a climate supporting an ocean on the surface.
Finally, the last three planets - TRAPPIST-1f, g and h - are located on the outer edge of the star system and most likely frozen worlds.
"This is a whole sequence of planets that can give us insight into the evolution of planets, in particular around a star that is very different from ours, with different light coming off of it," said Andrew Lincowski, UW doctoral student and lead author of the study.
"It's just a gold mine."
The findings of the study are published in The Astrophysical Journal.
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