Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2023

Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars

S Dalal
R D Haywood
  • Fonction : Auteur
A Mortier
W J Chaplin
  • Fonction : Auteur

Résumé

To detect Earth-mass planets using the Doppler method, a major obstacle is to differentiate the planetary signal from intrinsic stellar variability (e.g. pulsations, granulation, spots, and plages). Conv ectiv e blueshift, which results from small-scale convection at the surface of Sun-like stars, is rele v ant for Earth-twin detections as it exhibits Doppler noise of the order of 1 m s -1 . Here, we present a simple model for conv ectiv e blueshift based on fundamental equations of stellar structure. Our model successfully matches observations of conv ectiv e blueshift for FGK stars. Based on our model, we also compute the intrinsic noise floor for stellar granulation in the radial-velocity observations. We find that for a given mass range, stars with higher metallicities display lower radial-velocity dispersion due to granulation, in agreement with magnetohydrodynamic simulations. We also provide a set of formulae to predict the amplitude of radial-velocity dispersion due to granulation as a function of stellar parameters. Our work is vital in identifying the most amenable stellar targets for Extreme Precision Radial Velocity surv e ys and radial velocity follow-up programmes for TESS, CHEOPS, and the upcoming PLATO mission.

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hal-04960947 , version 1 (21-02-2025)

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S Dalal, R D Haywood, A Mortier, W J Chaplin, N Meunier. Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars. Monthly Notices of the Royal Astronomical Society, 2023, 525 (3), pp.3344 - 3353. ⟨10.1093/mnras/stad2393⟩. ⟨hal-04960947⟩
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