Kepler-196 and Its Three Planets

Kepler-196 is a star located 1470 light-years away, and three planets have been reported to orbit it. The star has an age of 3.98 billion years, a mass of 0.85 solar masses, and a radius of 0.79 solar radii. Its reported temperature is 5160 K. The star's reported mass and radius estimates are smaller than the Sun's, and its reported temperature is cooler than the Sun's.

Kepler-196 b is a Super-Earth discovered by the transit method in 2014. It has a radius of 1.9 Earth radii and an orbital period of 20.7 days. Among the listed planets, it has the shortest year and the smallest radius by reported estimates. Kepler-196 c, also a Super-Earth, was discovered by transit in 2014. Its radius is 2.24 Earth radii, and its orbital period is 47.4 days, giving it the second-shortest year and second-smallest radius among the listed planets. Kepler-196 d is a Neptune-like planet discovered by transit in 2021. It has a radius of 2.66 Earth radii and an orbital period of 122 days, making it the longest-year and largest-radius planet among the listed planets. The radius estimates of all three planets are larger than Earth's.

A transit occurs when a planet passes in front of its star from our viewpoint, causing a small dip in observed brightness; repeated dips help establish orbital periods. The size classes compare radius with Earth's: a Super-Earth reaches 2.5 times Earth's radius, while a Neptune-like planet reaches 4 times. An orbital period is the time a planet takes to complete one orbit - its year.