Kepler-281: A Distant Star and Its Three Worlds

Kepler-281 is a star located 5690 light-years away, and three planets have been found orbiting it. The host star is 4.68 billion years old and contains 0.95 solar masses, with a radius of 0.93 solar radii. Its reported temperature of 5620 K is cooler than the Sun's. All three planets were detected by the transit method, in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness.

Kepler-281 b is a Neptune-like planet discovered in 2014. It completes an orbit in 14.6 days, the shortest year among the listed planets, and has a radius of 2.82 Earth radii, the smallest of the three. Kepler-281 c, a Jupiter-like planet also discovered in 2014, orbits in 36.3 days, the second-shortest year among the listed planets, and has a radius of 5.31 Earth radii, the second-smallest. Kepler-281 d, another Jupiter-like planet, was discovered in 2021 and has the longest year of the group at 148 days. Its radius of 5.94 Earth radii is the largest among the listed planets. Each planet's reported radius estimate is larger than Earth's.