HD 189567 and Its Two Known Planets

HD 189567 is a star 58.4 light-years away with two planets, both discovered in 2021 by the radial velocity method, which detects the wobble a planet's gravity induces in its star's motion across repeated observations. The host is a G3V star, a Sun-like main-sequence dwarf, with an age of 9.76 billion years, a mass of 0.92 solar masses, a radius of 1.04 solar radii, and a temperature of 5710 K. Its reported mass estimate is smaller than the Sun's, while its reported radius estimate is larger than the Sun's and its reported temperature is cooler than the Sun's.

HD 189567 b has a minimum mass of 8.5 Earth masses and an orbital period of 14.3 days. Because this is a minimum mass, it represents a lower bound on the planet's true mass. Among the listed planets, HD 189567 b has the shortest year by reported estimates.

HD 189567 c has a minimum mass of 7 Earth masses and an orbital period of 33.7 days, also a minimum mass rather than a true mass. Among the listed planets, HD 189567 c has the longest year by reported estimates and the smallest minimum mass, while HD 189567 b has the largest minimum mass. Both planets' minimum masses are larger than Earth's.