There is also chances of their orbits being unsteady. Older stars are faster.
Scientists believe the star and its exoplanets are between 5.4 and 9.8 billion years old - as much as twice as old as our solar system.
Three of the TRAPPIST-1 planets reside in the star's "habitable zone", the orbital distance where a rocky planet with an atmosphere could have liquid water on its surface.
Additionally, the planets are tidally locked.
When the ultra-cool dwarf star Trappist-1 and its seven orbiting planets were first discovered 37 light-years away, scientists estimated it was at least 500 million years old, based on the size of low-mass star.
"We really had no handle on the age of Trappist-1", said Adam Burgasser, an astrophysicist with the University of California, San Diego. Might life have enough time to evolve on any of these worlds?
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. Their results will be published in The Astrophysical Journal.
According to NASA, the age of a star system is an important factor in determining its potential habitability. However, fortunately for any life on the planets in the TRAPPIST-1 system, the star is quieter than others of its kind.
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On the other hand, since the planets are so close to the star, they have soaked up billions of years of high-energy radiation, which could have boiled off atmospheres and large amounts of water, researchers said.
'Because of the onslaught by the star's radiation, our results suggest the atmosphere on planets in the Trappist-1 system would largely be destroyed, ' said Harvard professor Avi Loeb. All the seven planets in the system are closer to the host star than Mercury is to the Sun.
However, old age does not necessarily mean that a planet's atmosphere has been eroded.
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. But this could also backfire in a "runaway greenhouse" process, in which the atmosphere becomes so thick the planet surface overheats - as on Venus.
Seven near Earth objects were found near Trappist-1. 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.
TRAPPIST-1 is an ultracool dwarf star, not a yellow dwarf star like the Sun.
Astronomers reevaluated the TRAPPIST-1's age after measuring the speed at which the system is traveling through the Milky Way. These variables all pointed to a star that is substantially older than our Sun.
And, in the future, additional observations with NASA's Hubble Space Telescope and the James Webb Space Telescope could give further insight.