HD 113538 and Its Two Known Worlds

HD 113538 is a K9 V star located 53.1 light-years away. Its spectral type marks it as a K-type main-sequence dwarf, making it cooler than the Sun. That characterization is supported by its measured temperature of 4690 K. The star is also less massive and smaller than the Sun, with a reported mass of 0.7 solar masses and a radius of 0.65 solar radii. Its age is 1.3 billion years.

Two planets are known to orbit this host: HD 113538 b and HD 113538 c. Both were discovered in 2010 using the radial velocity method. This technique detects the gravitational wobble a planet induces in its star, and repeated wobbles reveal the planet and its orbital period.

HD 113538 b has a minimum mass of 114 Earth masses and an orbital period of 663 days, the shortest year among the listed planets. Its minimum mass is also the smallest among them, though it remains larger than Earth's. HD 113538 c is the more distant of the two, with a minimum mass of 296 Earth masses and an orbital period of 1820 days, marking the longest year and the largest minimum mass among the listed planets. Its minimum mass is likewise larger than Earth's.