Title: Planets Orbiting Other Stars
Speaker: Robert Noyes
Abstract: The past four years have seen the discovery of more than 25 sun-like stars orbited by companions with mass comparable to that of Jupiter. In one case three companions are known to orbit their central star, in an architecture reminiscent of our own solar system. However, these extra-solar planetary systems differ in major ways from our own solar system: many of the detected planets orbit extraordinarily close to their parent star; their masses are significantly larger than those of solar system planets; and except for the close-in companions, they typically have higher orbital eccentricity than do solar system planets. The recent discovery of a planet transiting in front of its parent star proves that these objects are gas giants, with properties rather similar to expectations if they formed at several astronomical units from the star, then migrated inward, and--somehow--stopped at the orbital distances where they are now seen. In this talk I will review the observational evidence bearing on the characteristics of extra-solar planets, and discuss possible avenues for future progress in understanding their nature, origin, and evolution.