Light curves produced by the Kepler mission demonstrate stochastic brightness fluctuations (or "flicker") of stellar origin which contribute to the noise floor, limiting the sensitivity of exoplanet detection and characterization methods. In stars with surface convection, the primary driver of these variations on short (sub-eight-hour) timescales is believed to be convective granulation. In this work, we improve existing models of this granular flicker amplitude, or $F_8$, by including the effect of the Kepler bandpass on measured flicker, by incorporating metallicity in determining convective Mach numbers, and by using scaling relations from a wider set of numerical simulations. To motivate and validate these changes, we use a recent database of convective flicker measurements in Kepler stars, which allows us to more fully detail the remaining model--prediction error. Our model improvements reduce the typical misprediction of flicker amplitude from a factor of 2.5 to 2. We rule out rotation period and strong magnetic activity as possible explanations for the remaining model error, and we show that binary companions may affect convective flicker. We also introduce an "envelope" model which predicts a range of flicker amplitudes for any one star to account for some of the spread in numerical simulations, and we find that this range covers 78% of observed stars. We note that the solar granular flicker amplitude is lower than most Sun-like stars. This improved model of convective flicker amplitude can better characterize this source of noise in exoplanet studies as well as better inform models and simulations of stellar granulation.
Differences in the fast optical variability of the dwarf nova V1504 Cyg between quiescence and outbursts detected in Kepler data and simulations of the rms-flux relations
The birth of Be star disks III. SPH models of localised mass ejections
Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo（圣保罗大学地球物理与大气科学天文研究所）；European Organisation for Astronomical Research in the Southern Hemisphere (ESO)（欧洲南方天文台）；DTU Space, Technical University of Denmark（丹麦技术大学空间中心）；LIRA, Paris Observatory, CNRS, PSL University, Sorbonne University, Université Paris Cité, CY Cergy Paris University（巴黎天文台LIRA实验室）；Department of Physics and Astronomy, Western University（韦仕敦大学物理与天文学系）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）
Mitigating flicker noise in high-precision photometry. I -- Characterization of the noise structure, impact on the inferred transit parameters, and predictions for CHEOPS observations
