The observed exoplanetary systems have exhibited a surprising diversity. First I will briefly review what we have learned so far for exoplanetary systems, and then focus on the statistics of the spin-orbit angle (the angle between stellar spin and the planetary orbital axes) . Indeed a number of the transiting gas giant planetary systems show significant spin-orbit misalignments. This unexpected fact has been mainly revealed by a spectroscopic method, known as the Rossiter-McLaughlin effect for transiting planets. This method measures the projected angle between the stellar spin and the planetary orbital axes, but is insensitive to the obliquity of the stellar spin with respect to the observer. In contrast, asteroseismology offers a unique method to infer the stellar obliquity in a complementary fashion. After describing the principle of measurements and the current statistics of the spin-orbit angles, I will present our recent work on the spin-orbit architectures with asteroseismology, and finally discuss its implications for origin and evolution of spin-orbit (mis)alignments of exoplanetary systems.
