Retrograde Orbits of Exoplanets Discovered

[dougettinger]

Recent observations and studies reveal that there are a large fraction of discovered exoplanets with retrograde orbits (Royal Astronomical Society Press Release). Also, numerous of the "hot Jupiters" are misaligned with the rotation axis of their parent stars. These discoveries do not bode well for the nebular hypothesis. Somebody from the forum postulated that some violient interactions could well have generated these retrograde inner planets.

Does anybody else have their own "pet" reason ? I believe that in a cluster of stars that are closer together the larger stars may capture planets from other stars or capture a planet that has been ejected from anther star system. These captured planets would have no connection to the formation processes in a protostar disk. Does anybody have reason to accept or reject this reason ?

Doug Ettinger
Pittsburgh, PA

[Chris Peterson]

Recent observations and studies reveal that there are a large fraction of discovered exoplanets with retrograde orbits (Royal Astronomical Society Press Release). Also, numerous of the "hot Jupiters" are misaligned with the rotation axis of their parent stars. These discoveries do not bode well for the nebular hypothesis.

Actually, these observations don't argue against the nebular hypothesis at all. They simply reveal how much more we have to understand about the complex environment around a protostar. If you read the scientific commentary on this new research, you don't find many arguing for an entirely new theory of planetary system formation.

Keep in mind that the "nebular theory" isn't really a theory, but is a label for a variety of theories. In the same way, the "Big Bang theory" isn't a theory, but a broad label given many theories. That planetary systems evolve in protostellar nebulas is hardly disputed- after all, we can see it happening directly in many places. The discussion is around the details, and it is observations like you reference that allow these details to be filled in, and the range of nebular theories to be narrowed down.