HD 7924: A Nearby K-Type Star and Its Three Known Worlds

HD 7924 is a K0 star located 55.4 light-years from Earth. Its reported mass is 0.83 solar masses and its radius is 0.78 solar radii, both smaller than the Sun's corresponding values. The star's reported temperature of 5180 K is cooler than the Sun's. Its age is given as 0.88 billion years. Three planets are known to orbit this host.

All three planets were found by the radial velocity method, which detects the wobble a planet's gravity induces in its star's motion. HD 7924 b was discovered in 2008, while HD 7924 c and HD 7924 d were both discovered in 2015.

HD 7924 b has a minimum mass of 6.36 Earth masses and an orbital period of 5.4 days. HD 7924 c has a minimum mass of 7.86 Earth masses and an orbital period of 15.3 days. HD 7924 d has a minimum mass of 6.44 Earth masses and an orbital period of 24.5 days. A minimum mass is a lower bound on a planet's true mass, distinct from an ordinary mass estimate. The minimum masses of all three planets are larger than Earth's.

Among the listed planets, HD 7924 b has the shortest year by reported estimates, at 5.4 days, and the smallest minimum mass, at 6.36 Earth masses. HD 7924 c has the second-shortest year, at 15.3 days, and the largest minimum mass, at 7.86 Earth masses. HD 7924 d has the longest year, at 24.5 days, and the second-smallest minimum mass, at 6.44 Earth masses. Its orbital period, 24.5 days, is the longest reported among the three planets.