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Paper: Spectroscopic Microvariability Induced by Convective Motions
Volume: 448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
Page: 1013
Authors: Porter, L.; Asplund, M.
Abstract: Convection reaches the atmospheres of cool stars creating detectable variability in the photometry and spectrum of the star. Current 3D hydro-dynamical models of dwarfs and red giants simulate only a small representative volume of the stellar atmosphere, typically covering some 10 granules horizontally. To derive observable quantities it is necessary to integrate these ‘Box-in-a-star’ models over the stellar disk. The disk-integrated variability caused by convective motions can be constrained using the statistical properties of spatial and temporal fluctuations from a time-series of these models. Previously suggested for white light and photometric centroid (Ludwig 2006), we extend this method to spectral lines, including the effects of stellar rotation. We believe a better characterisation of this convective microvariability would benefit velocity diagnostics for helioseismology, eg NiI 6768 Å, used by SOHO MDI (Jones 1989) and could be used to remove the ‘noise’ induced by convective motions in radial velocity planet searches.
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