K2-290: A Distant Star With Two Transit-Detected Planets

K2-290 is a star located 890 light-years from Earth. It has an age of 4 billion years, a mass of 1.19 solar masses, a radius of 1.51 solar radii, and a temperature of 6300 K. Its reported mass, radius, and temperature estimates are each larger than or hotter than the Sun's corresponding values. Two planets orbit this host: K2-290 b and K2-290 c. Both were discovered by transit in 2019, a method that detects the small dip in a star's brightness when a planet passes in front of it, with repeated dips helping to establish orbital periods.

K2-290 b is Neptune-like, with a radius of 3.06 Earth radii and a reported upper limit of 10.9 Earth masses. Its radius is larger than Earth's. It completes an orbit in 9.21 days, the shortest orbital period among the listed planets.

K2-290 c is Jupiter-like, with a radius of 11.3 Earth radii and a mass of 246 Earth masses. Its radius and mass are both larger than Earth's. Its mean density is 0.945 g/cm³, which is 0.172 times Earth's. It completes an orbit in 48.4 days, the longest orbital period among the listed planets.