HD 20003 and Its Two Known Planets

HD 20003 is a G8 V star 136 light-years from Earth. Its reported mass of 0.96 solar masses, radius of 0.929 solar radii, and temperature of 5490 K sit near solar values, though the star is slightly smaller and cooler than the Sun. Two planets are known to orbit this host.

Both planets were discovered in 2019 by the radial velocity method, which detects the wobble a planet's gravity induces in its star's motion; repeated wobbles reveal a planet and its orbital period. Each has a minimum mass, a lower bound on its true mass rather than an ordinary mass estimate. HD 20003 b has a minimum mass of 11.7 Earth masses and an orbital period of 11.8 days, the shortest year among the listed planets. HD 20003 c has a minimum mass of 14.4 Earth masses and an orbital period of 33.9 days, the longest year among the listed planets. Both minimum masses exceed Earth's. Among the listed planets, HD 20003 b has the smallest minimum mass and HD 20003 c the largest.