A basal contribution from p-modes to the Alfv\'enic wave flux in the Sun's corona

TL;DR

This paper reveals that internal acoustic modes in the Sun contribute to the basal Alfvénic wave flux in the corona, challenging the assumption that flux is generated only in the photosphere, with implications for stellar atmosphere models.

Contribution

It demonstrates that internal acoustic modes provide a continuous, ubiquitous source of Alfvénic wave energy in the Sun's corona, a novel insight into coronal energy transfer.

Findings

Internal acoustic modes contribute to the basal Alfvénic wave flux.

The contribution is spatially ubiquitous and persists over the solar cycle.

This challenges the traditional view of flux generation solely in the photosphere.

Abstract

Many cool stars possess complex magnetic fields [1] that are considered to undertake a central role in the structuring and energising of their atmospheres [2]. Alfv\'enic waves are thought to make a critical contribution to energy transfer along these magnetic fields, with the potential to heat plasma and accelerate stellar winds [3] [4] [5]. Despite Alfv\'enic waves having been identified in the Sun's atmosphere, the nature of the basal wave energy flux is poorly understood. It is generally assumed that the associated Poynting flux is generated solely in the photosphere and propagates into the corona, typically through the continuous buffeting of magnetic fields by turbulent convective cells [4] [6] [7]. Here we provide evidence that the Sun's internal acoustic modes also contribute to the basal flux of Alfv\'enic waves, delivering a spatially ubiquitous input to the coronal energy balance that is sustained over the solar cycle. Alfv\'enic waves are thus a fundamental feature of the Sun's corona. Acknowledging that internal acoustic modes have a key role in injecting additional Poynting flux into the upper atmospheres of Sun-like stars has potentially significant consequences for the modelling of stellar coronae and winds.