Synergy between stellar compressible simulations and asteroseismology

July 7th, 2025 Synergy between stellar compressible simulations and asteroseismology Arthur Le Saux (AIM, CEA Paris-Saclay) [email protected] TASC 9 / KASC 16 Workshop Collaborators: A. Leclerc, G. Laibe (CRAL), P. Delplace, A. Venaille (ENS de Lyon) L. Bessila, S. Mathis (CEA Paris-Saclay) Internal rotation of stars poorly constrained Major issue: we still do not know the rotation rate of the solar core And accessing rotation profile of other stars remains extremely difficult García et al. (2007) 2 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 How to access the solar core? Neutrinos (e.g. Villante & Serenelli 2021): mostly constraints on nuclear reactions and T p-modes: low sensitivity to solar core g-modes: very sensitive, but evanescent in envelope f-modes: not only surface gravity waves, also bulk mode! (Leclerc et al. 2022) See A. Leclerc’s talk tomorrow! 3 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Building a numerical analog of the Sun Solar 1D model calibrated to observed characteristics of the Sun using MESA (Paxton et al. 2011) f-modes, Larson & Schou (2008) p-modes, Kieffer & Broomhall (2021) Parameters used for calibration: , , , , R⊙ L⊙ Rconv (Z/X)surf cs Variables that are adjusted: [Fe/H], YCZ, 𝛼MLT, fOV 4 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 2D solar simulation vh/vh,rms Simulations run with the fully compressible MUSIC code (e.g. Viallet et al. 2013 Goffrey et al. 2017) and rin = 0.15R⊙ rout = 0.9R⊙ and θmin =π 12 θmax =11π 12 Nr×Nθ= 1024 ×1024 BC periodic in -direction and reflective in -direction θ r Frozen scalar = Y (for EoS) 5 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Snapshot horizontal velocity Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Modes identification Christensen-Dalsgaard (2014) 6 [email protected] Predicted solar spectrum Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Modes identification Linear modes computed using the EVP class of the Dedalus code (Burns et al 2020) Predicted solar spectrum P[ v2 h][cm2s−2] p modes f modes g modes ω/2π[μHz] Le Saux & Leclerc et al. (2025) Christensen-Dalsgaard (2014) ˜ ℓ 6 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Modes identification Linear modes computed using the EVP class of the Dedalus code (Burns et al 2020) Predicted solar spectrum P[ v2 h][cm2s−2] p modes f modes g modes ω/2π[μHz] Le Saux & Leclerc et al. (2025) Christensen-Dalsgaard (2014) ˜ ℓ 6 [email protected] Eigenfunction f-mode Low degrees f-modes behave as topological waves, as predicted by Leclerc et al (2022) Compressibility of the simulation is key! Amplitude deeper as decreases ℓ Amplitude comparison between MUSIC and theoretical predictions ξh/ξh,0 r/R⊙ Le Saux & Leclerc et al. (2025) MUSIC Theory 7 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Rotation in other solar-like stars p-modes are predicted to be similarly excited by convection (e.g. Samadi & Goupil 2001) Recently, Bessila et al. (2024) showed theoretically that rotation can significantly decrease the amplitude of solar-like oscillations See L. Bessila’s talk on Friday! (Mathur et al. 2019) 10 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 But oscillations not detected in 54% of solar-like stars observed by Kepler (Mathur et al. 2019) Insights from compressible simulations Run 4 rotating simulations in 2.5D using MUSIC Motions align with rotation axis Smaller structures Ω 11 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 (Le Saux et al. in prep) Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Insights from compressible simulations Convective velocities decrease, as predicted for rotating MLT (Stevenson 1979, Bessila 2025) Rms velocities in the simulations vr+θ,rms vr,rms r/Rstar 12 [email protected] Amplitudes of p-modes Power spectra of radial velocity Le Saux et al. (in prep) Similar trends for all ℓ …but it seems that impact is more important than predicted by Bessila et al. (2024b)! Possible enhanced damping of p-modes? 13 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025 Checked for ℓ∈[0, 25] Summary Compressibility is key for synergy between global stellar simulations and asteroseismology Vlaykov, Le Saux et al. (in prep) New predictions for helioseismology to access the solar core Perspectives: Confirm impact of rotation on convection and p-modes New description of low degree f-modes Coupling between f/g modes may provide the best chances of accessing the solar core ! Develop tools to improves the synergy with observations Progressively increase complexity for more realistic models (MHD, 3D…) More details: Le Saux et al 2025 ApJL 987 L12 [email protected] Arthur Le Saux - TASC 9 / KASC 16 - July 7th, 2025