Amplitude of solar gravity modes generated by penetrative plumes

Abstract

The detection of gravity modes is expected to give us unprecedented insights into the inner dynamics of the Sun. Within this framework, predicting their amplitudes is essential to guide future observational strategies and seismic studies. In this work, we predict the amplitude of low-frequency asymptotic gravity modes generated by penetrative convection at the top of the radiative zone. The result is found to depend critically on the time evolution of the plumes inside the generation region. Using a solar model, we compute the GOLF apparent surface radial velocity of low-degree gravity modes in the frequency range $10\mu H_z\le \nu \le 100\mu H_z$. In case of a Gaussian plume time evolution, gravity modes turn out to be undetectable because of too small surface amplitudes. This holds true despite a wide range of values considered for the parameters of the model. In the other limiting case of an exponential time evolution, plumes are expected to drive gravity modes in a much more efficient way because of a much higher temporal coupling between the plumes and the modes than in the Gaussian case. Using reasonable values for the plume parameters based on semi-analytical models, the apparent surface velocities in this case turn out to be one order of magnitude smaller than the 22-years GOLF detection threshold and than the previous estimates considering turbulent pressure as the driving mechanism, with a maximum value of $0.05$ cm s${}^{-1}$ for $\ell =1$ and $\nu \approx 100\mu H_z$. When accounting for uncertainties on the plume parameters, the apparent surface velocities in the most favorable plausible case become comparable to those predicted with turbulent pressure, and the GOLF observation time required for a detection at $\nu \approx 100\mu H_z$ and $\ell =1$ is reduced to about 50 yrs.

arXiv comment18 pages, Accepted for publication in A&A

References in corpus (33)

• The chemical composition of the Sun
• Helioseismology and Solar Abundances
• ADIPLS -- the Aarhus adiabatic oscillation package
• Seismic diagnostics for transport of angular momentum in stars 1. Rotational splittings from the PMS to the RGB
• Internal Gravity Waves in Massive Stars: Angular Momentum Transport
• Core rotation braking on the red giant branch for various mass ranges
• Oscillations of alpha UMa and other red giants
• Asymptotic g modes: Evidence for a rapid rotation of the solar core
• Internal Gravity Wave Excitation by Turbulent Convection
• Solar structure and evolution
• The quest for the solar g modes
• Three-Dimensional Simulations of Massive Stars: I. Wave Generation and Propagation
• Stochastic excitation of nonradial modes II. Are solar asymptotic gravity modes detectable?
• Theoretical seismology in 3D : nonlinear simulations of internal gravity waves in solar-like stars
• Numerical Simulations of Penetration and Overshoot in the Sun
• Can plume-induced internal gravity waves regulate the core rotation of subgiant stars?
• Spectrum and amplitudes of internal gravity waves excited by penetrative convection in solar-type stars
• Observational Searches for Solar g-modes: Some Theoretical Considerations
• Rotation rate of the solar core as a key constraint to magnetic angular momentum transport in stellar interiors
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum. I. Efficiency of transport during the subgiant phase
• Generation of internal gravity waves by penetrative convection
• Can mass loss and overshooting prevent the excitation of g-modes in blue supergiants?
• Extreme value statistics for two-dimensional convective penetration in a pre-Main Sequence star
• Fragile detection of solar g modes by Fossat et al
• Dynamic screening correction for solar p-p reaction rates
• Advances in Global and Local Helioseismology: an Introductory Review
• Searching for g modes: Part II. Unconfirmed g-mode detection in the power spectrum of the time series of round-trip travel time
• A comparison of the anelastic and subseismic approximations for low-frequency gravity modes in stars
• Sensitivity of a low threshold directional detector to CNO-cycle solar neutrinos
• A Critical Evaluation of Recent Claims Concerning Solar Rotation
• Seismic Solar Models from Ledoux discriminant inversions
• Signature of solar g modes in first-order p-mode frequency shifts
• Detecting gravity modes in the solar ${}^{8}B$ neutrino flux

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