(CN) – Scientists using a planet-hunting NASA satellite announced Monday the discovery of three new planets orbiting a nearby star, including one that may have had liquid water oceans.
In a paper published in the journal Nature Astronomy, astronomers using NASA’s Transiting Exoplanet Survey Satellite (TESS) found three exoplanets around the star TOI-270 about 73 light-years from Earth. While two are gaseous and about twice the size of Earth, the third one is rocky and only slightly larger than our home planet.
Researchers said the smaller of the three is located within the star’s habitable zone, meaning liquid-water oceans can possibly form on the planet and with it, the possibility of life. Additionally, since the star is relatively close to Earth and has few flares, scientists can observe the planet more clearly.
"We've found very few planets like this in the habitable zone, and many fewer around a quiet star, so this is rare," said Stephen Kan, associate professor of planetary astrophysics at University of California, Riverside. "We don't have a planet quite like this in our solar system."
Astronomers say our own solar system, made up of either small rocky planets or large gas giants, doesn’t contain a large rocky planet like the one observed orbiting the distant star.
"TOI-270 will soon allow us to study this ‘missing link’ between rocky Earth-like planets and gas-dominant mini-Neptunes, because here all of these types formed in the same system," said lead researcher Maximilian Gunther from the Massachusetts Institute of Technology.
The scientists said a follow-up observation mission is planned for 2020 when NASA will launch the James Webb Space Telescope. They plan to measure all three planets’ atmospheres for compositions of oxygen, carbon monoxide and hydrogen. Use of that data will help them determine if the planets ever had liquid water oceans and if they are suitable for sustaining life.
While TOI-270 is 73 light-years from Earth, it’s still considered a nearby star, Kane said.
"The diameter of our galaxy is 100,000 light-years, and our galaxy is just one of millions of galaxies," Kane said. "So, 73 light-years means it's one of our neighboring stars."
The study team said they hope to discover more planets surrounding the star, as they believe the surface of the smaller planet is likely too warm for the presence of water.
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