Now the new arrow estimation of scientists has raised new questions on the orbit immovability of the seven planets circling this new star system as well as its potentiality to host life.
"There's many earth size planets orbiting, probably most of the stars in the galaxy", said Burgasser.
At the time of its discovery earlier this year, scientists believed the TRAPPIST-1 system had to be at least 500 million-years-old. "This enabled us to essentially verify the existence of the two outer, potentially habitable planets in the system", University of Hertfordshire astronomer and co-author Mikko Tuomi explained.
The habitable zone, however, doesn't guarantee habitability, it simply defines a range of orbital distances at which water could in theory exist as a liquid.
TRAPPIST-1 is an ultracool dwarf star, not a yellow dwarf star like the Sun.
Since Tau Ceti is only 12 light-years away, the four planets are reportedly visible to the naked eye, even if they are some of the smallest planets ever found orbiting nearby sun-like stars. Because they're so close, it's possible that the equivalent of an ocean has evaporated from each TRAPPIST-1 planet, except for the two farthest from the star.
NASA said it's "unclear" what TRAPPIST-1's old age means for the planets' habitability.
Additionally, the planets are tidally locked.
Much has been said about the "ultra-cool dwarf star" that is hosting the planetary system, but the noise around it had sort of faded - until now. There is no day-night cycle on the planets in the TRAPPIST-1 system, one side experience a perpetual day, the other a never ending night, with a constant twilight zone between the two regions.
"If there is life on these planets, I would speculate that it has to be hardy life, because it has to be able to survive some potentially dire scenarios for billions of years", Burgasser said. Our own solar system was formed some 4.5 billion years ago. NASA researchers have now found out that the TRAPPIST-1 system is older than the solar system. All three factors suggest the system is significantly older than our solar system.
However, the planets in the TRAPPIST-1 system are of a lower density than Earth, which could mean that they could have a dense atmosphere with a lot of water vapour content, which would act as effective shields against the stellar radiation.
"This means the planets had to evolve together, otherwise the system would have fallen apart long ago", said Burgasser, first author of the research published in The Astrophysical Journal.