HD 177830 and Its Two Known Planets

HD 177830 is a K0 star located 205 light-years away. Its reported mass is 1.37 solar masses and its reported radius is 2.81 solar radii, both larger than the Sun's corresponding values. The star's reported temperature of 5060 K is cooler than the Sun's, and its age is given as 3.46 billion years. Two planets have been found around this star.

HD 177830 b was discovered in 1999 by the radial velocity method, which detects the wobble a planet's gravity induces in its star's motion. The planet's minimum mass is 537 Earth masses and its orbital period is 410 days; among the listed planets, it has the longest year. That minimum mass is larger than Earth's and is roughly 1.69 times Jupiter's mass.

HD 177830 c was discovered in 2010, also by radial velocity. Its minimum mass is 47.7 Earth masses and its orbital period is 111 days; among the listed planets, it has the shortest year and the smallest minimum mass. Its minimum mass is likewise larger than Earth's, while the minimum mass of HD 177830 b remains the largest among the listed planets.

A minimum mass is a lower bound on a planet's true mass, so these figures represent how light each world could be rather than its exact mass.