Distant star system yields clues to planet formation

Ars Technica : Located 129 light-years from Earth is the star system HR 8799. Because it is younger and hotter than our solar system, its four large planets retain enough heat from their formation that astronomers can directly image them in the IR. Two recent studies have provided new information about this system: One study is an overview of all four of the exoplanet candidates, and the other focuses on just one of the four. At first it was thought that the large orbiting bodies were brown dwarfs because of their size and brightness. But chemical and gravitational analyses of HR 8799c, the second-farthest out of the four, point more toward its being a planet. However, its lack of methane, present in all Jupiter-like planets, was a surprise. Further observations of the HR 8799 system could provide better insight into how planets are formed and help improve our models of star systems.