HD 108236: A Sun-Like Star and Its Five Known Planets

HD 108236 is a G5 star located 211 light-years away. Its reported mass estimate is 0.869 solar masses and its reported radius estimate is 0.877 solar radii, both smaller than the Sun's. With a reported temperature of 5660 K, it is cooler than the Sun, and its age is 6.7 billion years. Five planets are known to orbit this star, all discovered by the transit method, which detects the small dip in observed brightness when a planet passes in front of its star from our viewpoint.

HD 108236 b and HD 108236 c are both classified as Super-Earths. HD 108236 b has an orbital period of 3.8 days and a reported radius estimate of 1.62 Earth radii, while HD 108236 c has an orbital period of 6.2 days and a reported radius estimate of 2.07 Earth radii. Among the listed planets, HD 108236 b has the shortest year and the smallest radius by reported estimates; HD 108236 c has the second-shortest year.

TOI-1233.01 is a Neptune-like planet with an orbital period of 14.2 days and a reported radius estimate of 2.54 Earth radii, the second-largest among the listed planets. HD 108236 e, also Neptune-like, has an orbital period of 19.6 days and a reported radius estimate of 3.08 Earth radii, the largest among the listed planets and the second-longest year. HD 108236 f, a Super-Earth, has an orbital period of 29.5 days and a reported radius estimate of 2.02 Earth radii, giving it the longest year and the second-smallest radius among the listed planets.

Every listed planet has a reported radius estimate larger than Earth's. In size-class terms, a Super-Earth reaches 2.5 times Earth's radius, while a Neptune-like planet reaches 4 times; these classes compare radius, not composition.