The seven exoplanets around the star TRAPPIST-1, 40 light-years away, consist mainly of rock and potentially have more water than Earth, a new study has revealed. One of the exoplanets - TRAPPIST-1e - is more similar to the Earth than any other that has been found to date.
The study, carried out by an international team led by the University of Bern, suggests that of the known exoplanets (planets outside our solar system), TRAPPIST-1e most resembles the Earth in terms of its size, density, and the amount of radiation that it receives from its star.
TRAPPIST-1e is the only one of the seven TRAPPIST-1 planets that is somewhat denser than the Earth, and the existence of liquid water on its surface has not been ruled out, the University of Bern said on Monday in a statementexternal link. The international study was published in the journal Astronomy and Astrophysics.
The statement said that at least five of the lighter planets have a covering of volatile substances in the form of atmospheres, oceans or layers of ice. The planets' densities suggest that some could have up to 5% of their mass in water – which is 250 times more than the oceans on Earth.
The team measured the precise density of the seven exoplanets in terms of their size, mass and irradiation, with an uncertainty of less than 10%, which is “a first and a decisive step in the characterisation of potential habitability”, Brice-Olivier Demory, Professor at the University of Bern and co-author of the study, declared. The research team identified 35 parameters and developed a new algorithm to estimate the mass of the seven planets.
The seven planets around the cool red dwarf star TRAPPIST-1, which is 40 light years from Earth, or 370,000 billion kilometres, were discovered during the past two years with ground-based instruments and NASA space telescopes. As of February 1, 2018, 3,728 planets have been identified in 2,794 planetary systems, according to the site Exoplanet.euexternal link.