HIP 8152: A Nearby Star with Two Neptune-like Worlds

HIP 8152 is a star 332 light-years from Earth with two known planets. The star is 6 billion years old and has a mass of 0.937 solar masses, a radius of 0.96 solar radii, and a temperature of 5620 K. Its mass, radius, and temperature are each smaller or cooler than the Sun's corresponding values.

Both planets were discovered by transit in 2023. HIP 8152 b and HIP 8152 c are each Neptune-like, a class that can reach four times Earth's radius. HIP 8152 b has a mass of 8.9 Earth masses, a radius of 2.54 Earth radii, and an orbital period of 10.8 days. HIP 8152 c has a mass of 10.7 Earth masses, a radius of 2.52 Earth radii, and an orbital period of 19.6 days. The orbital period is the time a planet takes to complete one orbit, its year. Among the listed planets, HIP 8152 b has the shortest year and the largest radius, while HIP 8152 c has the longest year, the smallest radius, and the largest reported mass.

HIP 8152 b's radius and mass are each larger than Earth's, and its mean density is 3.01 g/cm³, 0.546 times Earth's. HIP 8152 c's radius and mass are also larger than Earth's, and its mean density is 3.66 g/cm³, 0.665 times Earth's.