Ever since its discovery in 2017, the TRAPPIST-1 system has fascinated astronomers — and for good reason. The seven alien planets that orbit this nearby tiny star have provided us with an incredible opportunity to study a neighboring solar system — one that is both similar to and very different from our own.
Located 39 light-years (or 235 trillion miles) from Earth, in the Aquarius constellation, this alien solar system revolves around a red dwarf star dubbed TRAPPIST-1. Classified as an M dwarf star, TRAPPIST-1 is a lot smaller than our sun — and about 2,000 times less bright, as previously reported by the Inquisitr.
In fact, TRAPPIST-1 is so small it barely makes the cut as a star, notes Phys.org. This tiny red dwarf weighs 9 percent of our sun’s mass and measures about 12 percent of its radius — which makes it only a little larger than the gas giant, Jupiter.
The seven exoplanets that make up the system — named TRAPPIST-1b through TRAPPIST-1h — are all rocky, Earth-sized planets that have piqued astronomers’ interest, emerging as strong candidates in the search for life beyond our planet’s borders.
The immense appeal of the TRAPPIST-1 exoplanets has increased exponentially ever since it was discovered that three of these planets — TRAPPIST-1e, f, and g — orbit in the star’s habitable zone. This means that they sit close enough to their parent star for surface temperatures to allow the formation of liquid water — and potentially to give life a chance at evolving.
One of these three planets in particular — namely TRAPPIST-1e — seems to have great potential of hosting liquid water on its surface. A new study published this month in the Astrophysical Journal reveals that, of the seven exoplanets, TRAPPIST-1 e has the best chance of being an “Earthlike ocean world” and stands out as “an excellent choice for further study with habitability in mind.”
Earthlike Water World
According to the team who conducted the research, all seven of TRAPPIST-1’s exoplanets likely developed in a way similar to that of Venus. This means that any water or surface oceans pooling on these planets would have evaporated soon after the birth of the system — making way-too-dense, uninhabitable atmospheres.
However, things may have gone a bit differently in the case of TRAPPIST-1e. The exoplanet was found to be “the most likely of the seven to host liquid water on a temperate surface,” reports Phys.org — citing the University of Washington in Seattle, which led the investigation.
This conclusion is based on a newly developed climate model of the TRAPPIST-1 system, which examines each of the seven exoplanets individually and incorporates terrestrial climate and photochemistry models to gauge the atmospheres of these intriguing alien worlds.
“We are modeling unfamiliar atmospheres, not just assuming that the things we see in the solar system will look the same way around another star,” said study lead author Andrew Lincowski, a doctoral student at the University of Washington.
As he points out, his team set out to uncover what the atmospheres of the TRAPPIST-1 planets would look like, given the unique environmental conditions that characterize this system.
“This is a whole sequence of planets that can give us insight into the evolution of planets, in particular around a star that’s very different from ours, with different light coming off of it. It’s just a gold mine.”
Lots Of Oxygen In The Atmosphere
As Lincowski explains, the same processes that may have turned the TRAPPIST-1 exoplanets into Venus-like worlds, depleting them of any surface water, could have enriched their atmospheres with plenty of oxygen.
The evolution of these planets is strongly connected to a particular phase in the star’s early life, during which TRAPPIST-1 burned hotter and brighter than it does now — blasting the system with ultraviolet emissions. These violent outbursts would have left the planets with little to no surface water, while also impacting their atmospheres.
As water evaporates from a planet’s surface, ultraviolet light coming from the parent star splits the water molecules, releasing hydrogen out of the atmosphere and leaving behind substantial amounts of oxygen. This is because hydrogen is light enough to escape the atmosphere and float past the gravitational pull of a planet, whereas the heavier oxygen gets trapped inside.
“This may be possible if these planets had more water initially than Earth, Venus, or Mars,” said Lincowski.
“If planet TRAPPIST-1 e did not lose all of its water during this phase, today it could be a water world, completely covered by a global ocean. In this case, it could have a climate similar to Earth.”