KEPLER AND THE KUIPER BELT

The proposed field of view of the Kepler mission is at an ecliptic latitude of 55, where the surface density of scattered Kuiper Belt objects (KBOs) is a few percent that in the ecliptic plane. The rate of occultations of Kepler target stars by scattered KBOs with radii rk10 km is 106 to 104 star1 yr1, where the uncertainty reflects the current ignorance of the thickness of the scattered KBO disk and the faint-end slope of their magnitude distribution. These occultation events will last only 0.1 % of the planned texp 15 minute inte-gration time and thus will appear as single data points that deviate by tiny amounts. However, given the target photometric accuracy of Kepler, these deviations will nevertheless be highly significant, with typical signal-to-noise ratios (S/Ns) of 10. I estimate that 1–20 of the 105 main-sequence stars in Kepler’s field of view will exhibit detectable occultations during its 4 yr mission. For unresolved events, the S/N of individual occultations scales as t 1=2 exp, and the minimum detectable radius could be decreased by an order of magnitude to 1 km by searching the individual 3 s readouts for occultations. I propose a number of methods by which occultation events may be differentiated from systematic effects. Kepler should measure or significantly constrain the frequency of highly inclined, 10 km–sized KBOs