Prof. Dan Maoz 
Tel Aviv University

Date: Jan. 18, 2009

Title: Discovering Extrasolar Planets Using Gravitational Lensing

Abstract:

Over 300 extrasolar planets have been found over the past 15 years,
almost all of them using the "radial velocity" technique. Most of
these planets are "hot Jupiters" -- massive planets on very close
orbits -- around the stars nearest to us. These systems, which are
very different from our Solar system, are precisely those that the
technique is capable of discovering. Gravitational lensing, the
phenomenon that turned Einstein into a celebrity, provides a
complementary method that permits discovering planets of Earth-mass
and up, at Earth-Sun-like separations, around stars at Galactic
distances. After explaining the basics of extrasolar planet hunting by
means of lensing, I will show examples of such planets discovered in
the past few years. I will focus on the recent discovery, made
possible by data obtained at Wise Observatory, of the first planetary
system (i.e., with more than one planet) found via lensing. This
system is the first among known planet systems that is similar to our
Solar system. Ongoing observations promise to reveal the frequency of
Solar-like systems and Earth-like planets throughout our Galaxy.