HD 23472 and Its Five Planets

HD 23472 is a K4 V star 127 light-years away, with a mass of 0.67 solar masses, a radius of 0.71 solar radii, and a temperature of 4680 K. Its mass, radius, and temperature are all smaller or cooler than the Sun's. Five planets are known to orbit this star.

HD 23472 b, a Super-Earth discovered by transit in 2019, has a mass of 8.32 Earth masses, a radius of 2 Earth radii, and an orbital period of 17.7 days. Both its mass and radius are larger than Earth's, and its mean density is 5.73 g/cm³, 1.04 times Earth's. Its neighbor HD 23472 c, another Super-Earth found the same year by transit, has a mass of 3.41 Earth masses, a radius of 1.87 Earth radii, and an orbital period of 29.8 days; its mass and radius also exceed Earth's, and its mean density is 2.87 g/cm³, 0.521 times Earth's.

The remaining three planets were all discovered by transit in 2022. HD 23472 d is a Sub-Earth with a mass of 0.55 Earth masses, a radius of 0.75 Earth radii, and an orbital period of 3.98 days; its mass and radius are smaller than Earth's, and its mean density is 7.18 g/cm³, 1.3 times Earth's. HD 23472 e is also a Sub-Earth, with a mass of 0.72 Earth masses, a radius of 0.818 Earth radii, and an orbital period of 7.91 days; its radius is smaller than Earth's, and its mean density is 7.25 g/cm³, 1.32 times Earth's. HD 23472 f is an Earth-like planet with a mass of 0.77 Earth masses, a radius of 1.14 Earth radii, and an orbital period of 12.2 days; its radius is larger than Earth's, and its mean density is 2.89 g/cm³, 0.524 times Earth's. Among the listed planets, HD 23472 d has the shortest year at 3.98 days, while HD 23472 c has the longest at 29.8 days.