Detecting Planets through Microlensing

Kailash C. Sahu
Space Telescope Science Institute
Baltimore MD

More than 200 microlensing events have been detected during the last ~4 years, most of them towards the galactic bulge. Since the line of sight towards the bulge passes through the disk and the bulge itself, the known stars towards the bulge play a dominant role as gravitational lenses. If these stars have planets around them, then the signature of the planets can be seen as sharp, extra peaks on the microlensing light curves. Frequent, continuous monitoring of the on-going microlensing events thus provides a powerful new method to search for planets around lensing stars.

In this talk, I will first review the background on stars acting as gravitational lenses. I will then review the theoretical work on possible observational features due to planets, and the probability of their detection through microlensing. PLANET (Probing Lensing Anomalies NETwork) is a collaboration actively involved at present in such a monitoring program, and some results from the PLANET collaboration will be discussed. Status of some other similar efforts will be briefly discussed.