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Session 70 - Searching for Other Planetary Systems.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center

[70.17] The Photometric Method for the Detection of Extrasolar Planets

M. S. Giampapa (NOAO/NSO), E. R. Craine (Western Research, Inc.), D. A. Hott (U. Cincinnati)

We offer further perspectives on the application of the photometric technique to the search for extrasolar planets. The principal obstacles to this approach include the ambiguous interpretation of the photometric signature of a possible transit event arising from the potential for confusion with stellar activity, and (2) the observational intensity of the search technique. We emphasize that the former issue can be addressed through multiband observations combined with considerations of the characteristic time scales of forms of stellar activity compared to that of a transit event. In the case of the latter concern, the advent of modern, automated telescope technologies offers the realistic prospect of meeting the demanding observational requirements of this approach.

We find that joint visual and near infrared observations are necessary to immediately distinguish between, for example, a planetary transit and a cool spot on the stellar surface. However, these observations by themselves do not appear sufficient to distinguish between a brown dwarf and a Jovian-size planetary companion of a dwarf M star. In such cases, other complementary observations will be necessary. We develop a computer simulation to estimate the average number of transits per year that would be presented for a stellar sample characterized by realistic properties in terms of spectral type distribution, effective temperatures, masses, and radii. A simple thermal model is adopted to estimate star-planet separations. The simulation suggests that the frequency of transit events will be dominated by M dwarf systems. This is due to the large number of these objects combined with the relative proximity to these cool stars within which planetary formation can occur according to current models.

Program listing for Wednesday