Acoustic Egression-Power Maps: Insights into Solar Dynamics and Energetic Events
Hi! I hope you guys are fine. Recently I was reading this paper on Solar quakes and came across egression power maps and couldn’t understand it. As Google says Regression models always. so what is Egression Power Maps?
Egression Power Maps are a valuable tool in the field of helioseismology, particularly in the study of solar quakes and the analysis of solar flares. These maps visually represent the acoustic power or energy generated by seismic sources on the Sun’s surface, offering valuable insights into the dynamics and energy distribution of various solar events.
Acoustic egression-power maps are generated using a technique called helioseismic holography, which analyzes the wave fields observed on the Sun’s surface to infer the properties of subsurface structures and dynamics.
Solar Dynamics is a fascinating field, and one of the tools that have proven invaluable in the study of solar quakes and flares are acoustic egression-power maps. Now you may ask what we mean by that and how this plays a crucial part.
Solar Dynamics is the study of sun’s dynamic process- things like earthquakes, flares, and other phenomena that occur on the surface and in the interior of the sun.The key concepts underlying acoustic egression-power maps are acoustic power, egression, and helioseismic holography. Acoustic power refers to the energy per unit of time radiated by acoustic waves, which in the context of the Sun are the pressure waves generated by dynamic events, including solar flares. Egression, on the other hand, refers to the outward propagation of these acoustic waves from their source region, in contrast with ingression, which pertains to the inward propagation of waves. Helioseismic holography is a method that uses the observed wave fields on the solar surface to reconstruct and analyze the wave sources and their properties beneath the surface
To create acoustic egression-power maps, data is first collected from instruments like the Helioseismic and Magnetic Imager on NASA’s Solar Dynamics Observatory, which captures oscillations and waves in the Sun’s photosphere. The observed wave fields are then analyzed using helioseismic techniques, with helioseismic holography being used to calculate the egression power by considering the outward-propagating waves and reconstructing the wave sources. The resulting egression power is then mapped spatially to visualize the distribution of acoustic energy across the Sun’s surface, with high egression-power regions indicating strong acoustic sources, such as solar flares.
Now you may ask what wave fields are.
The observed wave fields are the oscillations and waves captured on the Sun’s photosphere by instruments like the Helioseismic and Magnetic Imager on NASA’s Solar Dynamics Observatory. These wave fields are then analyzed using helioseismic techniques, particularly the method of helioseismic holography, to calculate the egression power and reconstruct the wave sources.
The solar dynamo is sustained by the exchange between toroidal flux, represented by sunspots, and the poloidal flux, represented by polar field strength. Solar eruptions are part of the life cycle of active regions, in that photospheric motions store energy in AR magnetic fields, and the stored energy is explosively released. The turbulent solar convection zone is dominated by acoustic waves with periods between two and ten minutes, and these acoustic waves are used in helioseismology to probe the interior of the Sun.
Acoustic egression-power maps are powerful tools that help visualize the acoustic power generated by seismic sources on the Sun’s surface, providing valuable insights into solar events’ dynamics and energy distribution.
Some important points to note about acoustic egression-power maps:
- Acoustic egression-power maps visually represent the acoustic power or energy generated by seismic sources on the Sun’s surface (Mercea et al., 2023).
- These maps are generated using helioseismic holography, a technique that analyzes the wave fields observed on the Sun’s surface to infer the properties of subsurface structures and dynamics.
- Acoustic power refers to the energy per unit of time radiated by acoustic waves, which are pressure waves generated by various dynamic events, including solar flares.
- Egression refers to the outward propagation of these acoustic waves from their source region, in contrast with ingression, which pertains to the inward propagation of waves.
- Helioseismic holography is a method that uses the observed wave fields on the solar surface to reconstruct and analyze the wave sources and their properties beneath the surface.
- The generation of acoustic egression-power maps involves data collection, wave field analysis, and spatial mapping of the egression power to visualize the distribution of acoustic energy across the Sun’s surface.
The applications of acoustic egression-power maps are diverse, as they provide valuable insights into the dynamics and energy distribution of solar events (Shen et al., 2022). These maps can be used to study the properties of solar quakes, which are seismic emissions visible on the solar surface and are associated with some solar flares. By analyzing the patterns and variations in acoustic egression-power maps, researchers can better understand the underlying processes driving these energetic solar events, ultimately contributing to our knowledge of the Sun’s complex and dynamic behaviour.
Here are a few references I cited from:
