WaLSA Team

The Waves in the Lower Solar Atmosphere (WaLSA) team is an international consortium focused on investigating wave activity in the Sun's lower atmosphere. The team's research seeks to understand how magnetohydrodynamic (MHD) waves generated within the Sun's interior and lower atmosphere influence the dynamics and heating of its outer layers.

The WaLSA team's research has been supported by the Research Council of Norway through Rosseland Centre for Solar Physics (project no. 262622), The Royal Society (award no. Hooke18b/SCTM), and the International Space Science Institute (ISSI Team 502).

Research
Understanding the Sun's atmospheric heating: The role of waves

The WaLSA team's research centers on understanding various wave modes propagating through solar structures of diverse sizes and properties. To achieve this, the team leverages the highest-resolution imaging and spectropolarimetric observations available. The key objectives include:


 * Investigating the coupling mechanisms between different wave modes.
 * Determining accurate measurements of the energy carried by MHD waves into the Sun's upper atmosphere.
 * Understanding wave dissipation mechanisms and their contribution to heating the outer atmospheric layers.

The team employs a combination of high-resolution observations, theoretical modelling, and numerical simulations to achieve these objectives.

Waves in the Lower Solar Atmosphere
The Sun's lower atmosphere, encompassing the photosphere (visible surface) and the chromosphere, is a dynamic realm where waves play a pivotal role in energy transport. This region is filled with complex interactions between the turbulent plasma and the Sun's powerful magnetic fields. These interactions give rise to various wave phenomena that can carry energy and momentum towards the outer layers of the solar atmosphere.

Key Wave Types
 * Acoustic Waves (p-modes): These are pressure-driven sound waves that ripple through the solar interior and become visible as oscillations on the Sun's surface.
 * Magnetoacoustic Waves: These waves are hybrids, combining properties of sound waves and magnetic disturbances. They can be further categorized:
 * Slow magneto-acoustic waves: These primarily travel along magnetic field lines and are thought to play a role in chromospheric heating.
 * Fast magneto-acoustic waves: These propagate more freely with less restriction by magnetic fields. They may contribute to energy transport towards the corona.
 * Alfvén Waves: These enigmatic waves involve oscillations of the magnetic field lines themselves, much like the vibrations of a plucked string. Alfvén waves are believed to be crucial for transporting energy from the lower atmosphere to the corona and accelerating the solar wind.

The Importance of Studying Waves

Understanding waves in the lower solar atmosphere is crucial for several reasons:
 * Chromospheric and Coronal Heating: The Sun's corona, reaching millions of degrees in temperature, is far hotter than the solar surface. Waves are prime candidates for transporting the energy needed to maintain these extreme temperatures.
 * Solar Wind: The solar wind, a stream of charged particles flowing outwards from the Sun, carries energy and impacts space weather near Earth. Waves likely play a role in accelerating the solar wind.
 * Solar Dynamics: Waves offer a unique window into the hidden processes occurring within the lower solar atmosphere. By studying their properties, we can deduce information about magnetic fields, plasma flows, and the complex energy balance of the Sun.
 * Space Weather: Waves in the lower solar atmosphere can influence the release of solar flares and coronal mass ejections (CMEs), as well as acceleration of solar wind, which can disrupt communications and power grids on Earth.

Observational Advancements

Recent advances in high-resolution solar telescopes, both ground-based and balloon-/space-borne, have revolutionised our ability to study waves in the lower solar atmosphere. These instruments provide unprecedented detail, allowing scientists to track wave propagation, measure their energy, and investigate their interaction with the Sun's magnetic structures.

The Future of Solar Wave Exploration

Research on waves in the lower solar atmosphere is a vibrant and rapidly evolving field. The next generation of solar telescopes, such as the Daniel K. Inouye Solar Telescope (DKIST) and the European Solar Telescope (EST), promises even more detailed views, aiding scientists in their quest to unravel the mysteries of how waves shape the Sun's dynamic atmosphere.