HD 73583 and Its Two Planets

HD 73583 is a K-type star 103 light-years away, and two planets have been found orbiting it. The star is classified as K4, which places it in a cooler temperature class than the Sun, and its reported temperature of 4580 K is cooler than the Sun's. Its reported mass of 0.702 solar masses and radius of 0.677 solar radii are each smaller than the Sun's, and it is 0.78 billion years old.

Both planets were discovered by transit, the method in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness; repeated dips help establish orbital periods. The two planets are HD 73583 b and HD 73583 c, both announced in 2022. HD 73583 b is Neptune-like, with a radius of 2.79 Earth radii and a mass of 10.2 Earth masses. Its radius and mass are each larger than Earth's, and its mean density is 2.59 g/cm³, 0.47 times Earth's. It completes one orbit in 6.4 days. Among the listed planets, HD 73583 b has the shortest year, the largest radius, and the largest reported mass.

HD 73583 c is a Super-Earth, with a radius of 2.39 Earth radii and a mass of 9.7 Earth masses. Its radius and mass are each larger than Earth's, and its mean density is 3.91 g/cm³, 0.711 times Earth's. Its orbital period is 18.9 days. Among the listed planets, HD 73583 c has the longest year, the smallest radius, and the smallest reported mass.