Moffett Field, CA, United States (4E) – U.S. astronomers have confirmed the first Earth-sized exoplanet orbiting in a habitable zone of another star.
The report on Kepler-186f published in Science Magazine on Friday said the exoplanet first discovered by NASA’s Kepler space telescope was confirmed by land-based telescopes in Hawaii to be like Earth in size and in a distance from the star that allows water to pool on its surface.
“What makes this finding particularly compelling is that this Earth-sized planet, one of five orbiting this star, which is cooler than the Sun, resides in a temperate region where water could exist in liquid form,” said Elisa Quintana of the SETI Institute and NASA Ames Research Center, according to Science Daily.
Kepler-186f resides in the Kepler-186 system, about 500 light-years from Earth in the constellation Cygnus. It has four companion planets smaller than Earth orbiting an M dwarf, a star half the size of the sun.
Kepler-186f orbits in the outer edge of the habitable zone once every 130 days. The other planets in the system–Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e–orbit around their sun every four, seven, 13, and 22 days, respectively, making them too hot for life.
Quintana, the co-author of the paper of Kepler-186f, said her team used the speckle imaging technique to confirm the size and distance of Kepler-186f. The technique was made possible using extremely high spatial resolution observations from the 26-foot Gemini North telescope on Mauna Kea in Hawaii and adaptive optics (AO) observations from the neighboring 33-foot Keck II telescope.
The Gemini “speckle” data directly imaged the system to within about 400 million miles of the host star to confirm that there were no other stellar size objects orbiting within that radius from the star. The Keck AO observations probed a larger region around the star but to fainter limits.