A library of stellar light variations due to extra-solar comets

We present an extensive study of stellar occultations by extra-solar cometary tails through a large number of numerical simulations. The output of the simulations are the star light extinction and scattering as a function of time at three wavelengths (400, 800 and 2200 nm). We explore the light curves dependence over a large set of possible parameters (dust size distributions, stellar types, production rates, orbital configurations). This grid of models, which is electronically available at http://www.iap.fr/users/lecaveli/grid/, will be useful to develop and to test the detection methods, and to analyze the results of the forthcoming high accuracy photometric surveys. With this tool, we quantify the proportion of light curves which could mimic a planetary occultation. We find that at a signal to noise ratio of 10, about 5% of cometary occultation light curves are symmetric enough to be mistaken for a planetary occultation. The total number of planet mimicing cometary occultations could be of the same order as the number of planet occultations.