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Paper: Activity of A-type Star KIC 7047141
Volume: 518, Physics of Magnetic Stars
Page: 195
Authors: Savanov, I. S.
Abstract: Photometric variability of the A star KIC 7047141 (candidate to flare stars among A-type objects) is investigated using the most complete set of observational material obtained with the Kepler Space Telescope. The analysis is based on 65251 individual brightness measurements in the interval of 1470 days (nearly four years). Analysis of the observations were performed using the activity software package developed by us for automated reduction and processing of Kepler Space Telescope archive data. This software package enabled us to reduce the original data as well as to carry out a search for rotation periods, determine the variability amplitude, etc. The periodicity of the brightness variations of KIC 7047141 with the period P1 = 2.949 days is confirmed. The second peak P2 = 1.476 days corresponds to half of the star's photometric rotation period and suggests the presence of two active regions on the stellar surface. Another peak with lower power P3 = 2.997 days can be due to the presence of spots at different latitudes on the differentially rotating star. In this case it can be explained as the existence of differential rotation with the parameter ΔΩ = 0.036. Changes in the amplitude of the brightness variability made it possible to determine the lap time (LT) which resulted in an independent estimation of the differential-rotation parameter ΔΩ = 0.024. From the analysis of the minima in the phased light curves we found positions of more active region on the stellar surface. We conclude that mostly the occupied positions of the active regions have bimodal distribution corresponding to phases 0.1–0.4 and 0.85–1.1.
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