Velocity-intensity asymmetry reversal of solar radial p-modes

Abstract

The development of space-borne missions has significantly improved the quality of the measured spectra of solar-like oscillators. Their $p$-mode line profiles can now be resolved, and the asymmetries inferred for a variety of stars other than the Sun. However, it has been known for a long time that the asymmetries of solar $p$-modes are reversed between the velocity and the intensity spectra. Understanding the origin of this reversal is necessary in order to use asymmetries as a tool for seismic diagnosis. For stars other than the Sun, only the intensity power spectrum is sufficiently resolved to allow for an estimation of mode asymmetries. We recently developed an approach designed to model and predict these asymmetries in the velocity power spectrum of the Sun and to successfully compare them to their observationally derived counterparts. In this paper we expand our model and predict the asymmetries featured in the intensity power spectrum. We find that the shape of the mode line profiles in intensity is largely dependent on how the oscillation-induced variations of the radiative flux are treated, and that modelling it realistically is crucial to understanding asymmetry reversal. Perturbing a solar-calibrated grey atmosphere model, and adopting the quasi-adiabatic framework as a first step, we reproduce the asymmetries observed in the solar intensity spectrum for low-frequency modes. We conclude that, unlike previously thought, it is not necessary to invoke an additional mechanism (e.g. non-adiabatic effects, coherent non-resonant background signal) to explain asymmetry reversal. This additional mechanism is necessary, however, to explain asymmetry reversal for higher-order modes.

arXiv comment9 pages, 4 figures. Accepted for publication in A&A

References in corpus (10)

• Excitation of stellar p-modes by turbulent convection: 1. Theoretical formulation
• Interaction Between Convection and Pulsation
• Line asymmetry of solar p-modes: Reversal of asymmetry in intensity power spectra
• Stellar oscillations. II The non-adiabatic case
• Calibration of the mixing-length parameter $\alpha$ for the MLT and FST models by matching with CO${}^5$BOLD models
• What Causes P-mode Asymmetry Reversal?
• Influence of metallicity on the near-surface effect on oscillation frequencies
• Asymmetry of line profiles of stellar oscillations measured by Kepler for ensembles of solar-like oscillators: impact on mode frequencies and dependence on effective temperature
• Modelling Solar Oscillation Power Spectra: II. Parametric Model of Spectral Lines Observed in Doppler Velocity Measurements
• Modelling the asymmetries of the Sun's radial $p$-mode line profiles

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