Planetary Transits toward the Galactic Bulge

The primary difficulty with using transits to discover extrasolar planets isthe low probability a planet has of transiting its parent star. One way ofovercoming this difficulty is to search for transits in dense stellar fields,such as the Galactic bulge. Here I estimate the number of planets that might bedetected from a monitoring campaign toward the bulge. A campaign lasting 10nights on a 10 meter telescope (assuming 8 hours of observations per night anda 5'x5' field of view) would detect about 100 planets with radius $\rp=1.5\rjup$, or about 30 planets with $\rp=1.0 \rjup$, if the frequency anddistribution of planets in the bulge is similar to that in the solarneighborhood. Most of these planets will be discovered around stars just belowthe turn-off, i.e. slightly evolved G-dwarfs. Campaigns involving 1- or 4-mclass telescopes are unlikely to discover any planets, unless there exists asubstantial population of companions with $\rp > 1.5 \rjup$.Comment: 4 pages, 4 figures. Submitted to ApJ Letter