Low temperatures make possible the presence of liquid water on their surface. Scientists have spotted seven Earth-sized planets, with mass similar to Earth, orbiting around a dwarf star the size of Jupiter, just 39 light years from the Sun. The planets’ temperature is low enough to make possible the presence of liquid water on their surface.
In May last year, scientists found three planets passing in front of TRAPPIST-1, the dwarf star. Based on further monitoring of the star from the ground and space, scientists have found four more ‘exo-planets’ orbiting TRAPPIST-1.Michaël Gillon from the University de Liege, Belgium is the first author of the paper.
“This is the first time we have so many Earth-like planets found around a star. The star is low-mass and small,” Dr. Gillon said. “The seven stars could have some liquid water and maybe life. These planets are found in the habitable zone of the star. This is the first time we have found so many planets in the habitable zone of a star.”
The four newly discovered planets orbit around the star every 4.04 days, 6.06 days, 8.1 days and 12.3 days respectively; the orbital period of two of the three planets discovered last year is 1.51 days and 2.42 days respectively.
Five planets have sizes similar to that of the Earth, while the remaining two are intermediate in size — between Mars and Earth. Based on the mass estimates, the six inner planets may have a rocky composition. The sixth planet has low density suggesting a volatile rich composition. The volatile content could be either ice layer and/or atmosphere.
1) In 2018, the James Webb Space Telescope will launch and be positioned 1 million miles from Earth with an unprecedented view of the universe. It can observe large exo-planets and detect starlight filtered through their atmosphere. The researchers are also searching for similar star systems to conduct more atmospheric research. Four telescopes named SPECULOOS (Search for habitable Planets EClipsing ultra-cool Stars) based in Chile will survey the southern sky for this purpose.
2) TRAPPIST-1 barely classifies as a star at half the temperature and a tenth the mass of the sun. It is red, dim and just a bit larger than Jupiter. But these tiny ultra-cool dwarf stars are common in our galaxy. The researchers used a telescope called TRAPPIST-(Transiting Planets and PlanetesImals Small Telescope) to observe its starlight and changes in brightness.