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Session 89 - Searching for Other Planetary Systems.
Oral session, Wednesday, January 17
Salon del Rey South, Hilton
Massive planets are already showing their presence by indirect detection. We are most interested in planets like those in our own system, particularly Earth-like planets and direct detection is needed to study their characteristics. The reflected light from a planet is a rough measure of its size. Adaptive optics techniques discussed by Angel will permit us to use large telescopes to see Jupiter-like planets around the nearest stars, but Earth is closer in and fainter. At 10pc it would be a 30th magnitude object 1/10 arcsec from a 5th magnitude star. In the infrared the contrast is one thousand times better and the photon rate is 20 times better. The emitted infrared radiation measures both a the temperature of its atmosphere and the planet's size. The spectrum of a planet measures its atmospheric composition and the atmospheric molecules show up far better in the infrared. Earth's spectrum shows water, carbon dioxide and oxygen in the form of ozone. These indicate habilitability and the existence of micro-organism life here. A nulling interferometer with meter size optics, operated at 5AU could image planetary systems out to 15pc and observe the planet spectra. The cost is manageble and it could be sent out within a decade.
