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Register a new userPreliminary results of dark-speckle stellar coronography
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A. Boccaletti DESPA
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The dark-speckle method (Labeyrie 1995) combines features of speckle interferometry and adaptive optics to provide images of faint circumstellar material. We present preliminary results of observations, and simulations concluding to the feasibility of exo-planet imaging from the ground. Laboratory simulations with an avalanche photodiode indicate the detectability of a stellar companion of relative intensity 10^{-6} at 5 Airy radii from the star. New, more general, expressions for the signal-to-noise ratio and integration time are given. Comparisons with direct long-exposure imaging indicate that the method improves the detectability of circumstellar nebulosity, faint companions and planets.
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We present a preliminary analysis of the photospheric activity of CoRoT-Exo-2a, a young G7V star accompanied by a transiting hot Jupiter recently discovered by CoRoT. We apply spot modelling techniques developed for the analysis of the Sun as a star and capable to extract from CoRoT high precision light curves information on the variation of the total spotted area and the longitude of active regions along the 142 days of the observations. This preliminary analysis shows that the active regions form within two active longitudes separated by about 180 degrees and rotating with periods of 4.5221 and 4.5543 days, respectively, and that the total spotted area oscillates with a period of about 28.9 days.
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