Red dwarfs emit a much stronger extreme ultraviolet (XUV) flux when young than later in life. Planets with a radius of more than 1.5 times that of Earth tend to accumulate the thick atmospheres which make them less likely to be habitable. A massive hydrogen/ helium (H/He) atmosphere is thought to be unlikely in a planet with a radius below 1.5 R Earth. For example, it could be a rocky terrestrial planet or a lower density ocean planet with a thick atmosphere. The planet is about 11% larger in radius than Earth (between 4.5% smaller and 26.5% larger), giving a volume about 1.37 times that of Earth (between 0.87 and 2.03 times as large).Ī very wide range of possible masses can be calculated by combining the radius with densities derived from the possible types of matter from which planets can be made. ![]() ![]() This ratio was measured to be 0.021, giving a planetary radius of 1.11☐.14 times that of Earth. The only physical property directly derivable from the observations (besides orbit) is the size of the planet relative to the central star, which follows from the amount of occultation of stellar light during a transit. Physical characteristics Mass, radius and temperature The public announcement was on 17 April 2014, followed by publication in Science. ![]() The results were presented initially at a conference on 19 March 2014 and some details were reported in the media at the time. Īnalysis of three years of data was required to find its signal. NASA's Kepler space telescope detected it using the transit method, along with four additional planets orbiting much closer to the star (all modestly larger than Earth). It was the first planet with a radius similar to Earth's to be discovered in the habitable zone of another star. ![]() Kepler-186f (also known by its Kepler object of interest designation KOI-571.05) is an exoplanet orbiting the red dwarf Kepler-186, about 580 light-years (180 parsecs) from Earth.
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