A Scenario for Origin of Global 4 mHz Oscillations in Solar Corona

Abstract

We establish a spherically symmetric model of solar atmosphere, which consists of the whole chromosphere and low corona below the 1.25 solar radius. It is a hydrodynamic model with heating in the chromosphere through an artificial energy flux. We performed a series of simulations with our model and found oscillations with a peak frequency of ∼4 mHz in the power spectrum. We confirmed that this resulted from the p-mode excited in the transition region and amplified in a resonant cavity situated in the height range ∼4×103–2×104 km. This result is consistent with global observations of Alfvénic waves in corona and can naturally explain the observational ubiquity of 4mHz without the difficulty of the p-mode passing through the acoustic-damping chromosphere. We also confirmed that acoustic shock waves alone cannot heat the corona to the observed temperature, and found mass upflows in the height range ∼7×103–7×104 km in our model, which pumped the dense and cool plasma into the corona and might be the mass supplier for solar prominences.

Keywords

• hydrodynamics
• methods: numerical
• sun: atmosphere
• sun: corona