JAPC - Worlds in Transit

Speaker: Dr. Kailash Sahu, Space Telescope Science Institute, Baltimore

Topic: "Worlds in Transit"

Time: 2:00 PM, Friday, April 20th, 2007

Place: P-148 (refreshments will be served at 1:45 PM in P146A)

Abstract: More than 200 extrasolar planets discovered so far, all of them around relatively nearby stars. The SWEEPS (Sagittarius Window Eclipsing Extrasolar Planet Search) project used HST to monitor 180,000 stars in the Galactic bulge continuously for 7 days to look for transiting extrasolar planets. The SWEEPS sample represents the farthest such sample, and includes stars down to 0.45 solar mass. We discovered 16 candidates with orbital periods between 0.4 and 4.2 days. In two cases, radial-velocity measurements support the planetary nature of the companions. Five candidates are ultra-short-period planets (USPPs) with orbital periods below 1.0 day, something that had not been seen before, and which occur only around stars of less than 0.88 solar mass. This indicates that those orbiting very close to more luminous stars might be evaporatively destroyed, or that jovian planets around lower-mass stars might migrate to smaller radii. The resulting frequency of planets in the Galactic bulge is similar to that in the solar neighborhood.

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