Abstract

I will talk about different populations of exoplanets and their interconnection. Specifically, I will present chemical composition measurements for hot Jupiters and directly-imaged young jovian planets, in an attempt to answer questions such as how stellar chemical composition controls the planet formation; how the difference of planetary and stellar chemical abundance reveals the history of orbital migration. In addition, I will highlight the recent progress in comparative planetology by contrasting (1) small planets with different densities and structures; and (2) Earth-size rocky planets vs. gas dwarf planets in the habitable zone. These comparative studies shed light on the origin of the diverse outcome of planet formation and the search for biosignatures with current and future facilities.