Groundbreaking Maps of the Sun’s Coronal Magnetic Fields

The Daniel K. Inouye Solar Telescope (DKIST) has mapped the Sun’s coronal magnetic fields for the first time, using the Zeeman effect to study spectral line splitting. This breakthrough will help predict space weather like solar flares, coronal mass ejections (CME), and the solar wind, which affect Earth’s magnetosphere and can cause damage to satellites and power grids.

Summary

• The Sun’s corona is responsible for space weather events like auroras, solar flares, CMEs, and the solar wind.
• The Daniel K. Inouye Solar Telescope (DKIST) has mapped the Sun’s coronal magnetic fields using advanced technology like the Cryogenic Near-Infrared Spectropolarimeter (cryo-NIRSP) and the Zeeman effect.
• The Zeeman effect allows scientists to observe spectral line splitting, revealing details about the Sun’s magnetic fields.
• This is the first time the magnetic fields in the Sun’s corona have been mapped, a key step in understanding space weather.
• Coronal mass ejections (CMEs) are a dangerous form of space weather that can cause geomagnetic storms on Earth.
• Understanding coronal magnetic fields can help scientists predict space weather and protect satellites and power grids from damage.
• The DKIST’s work will impact not just solar research but astronomy in general, aiding in understanding stars and their impact on planetary systems.

The Importance of Mapping the Sun’s Coronal Magnetic Fields

If you enjoyed this summer’s display of aurora borealis, thank the Sun’s corona. The corona is the Sun’s outer layer and is responsible for most space weather, including auroras. However, space weather isn’t always as benign as the beautiful light shows. Solar flares, coronal mass ejections (CMEs), and the solar wind can be dangerous and destructive.

Space weather refers to the various phenomena resulting from the Sun’s activity that affects Earth’s atmosphere and surrounding space environment. It includes:

• Solar flares: Powerful bursts of electromagnetic radiation that can disrupt radio communications and damage satellites.
• Coronal Mass Ejections (CME): Large expulsions of plasma from the Sun’s corona that can cause geomagnetic storms and disrupt power grids.
• Solar wind: A stream of charged particles from the corona that interacts with Earth’s magnetosphere, leading to auroras and other effects.

The Sun’s corona is composed of plasma and is incredibly hot, though it is much dimmer compared to the rest of the Sun. The corona produces space weather through solar flares, CMEs, and solar wind. However, despite its importance, scientists have long struggled to understand the magnetic fields that drive these phenomena.

The Daniel K. Inouye Solar Telescope: A New Era in Solar Research

To solve this mystery, scientists turned to the Daniel K. Inouye Solar Telescope (DKIST), the most powerful solar telescope in the world. Located in Maui, Hawai’i, this telescope has revolutionized our understanding of the Sun’s corona by successfully mapping its magnetic fields for the first time.

The telescope’s primary tool for this is the Cryogenic Near-Infrared Spectropolarimeter (cryo-NIRSP), which measures the intensity, velocity, density, and magnetic fields of the solar corona with unparalleled precision. The telescope also uses coronagraphy to create artificial eclipses, which enables it to see the corona and observe polarized signals that are billions of times fainter than the Sun’s disk.

The key to this breakthrough lies in the Zeeman effect, a phenomenon where the presence of a magnetic field causes spectral lines—the distinct “fingerprints” of atoms and molecules—to split. By studying this splitting, scientists can map the magnetic properties of the Sun’s corona.

Spectral lines are either absorbed or emitted by specific atoms and molecules. These lines become split in the presence of a magnetic field, and the DKIST uses this effect to measure the Sun’s magnetic fields with high precision. Previously, astronomers attempted to study the Zeeman effect in the corona but lacked the necessary detail and regularity. With the DKIST, this has changed.

The Challenge of Observing the Corona

One of the reasons it has been so difficult to observe the corona in detail is that it is much fainter than the Sun’s disk—about one million times fainter, to be exact. Before the DKIST, the corona could only be observed during solar eclipses. With the telescope’s coronagraphy technique, researchers can now view the faint polarized signals from the corona, allowing unprecedented observations of its magnetic fields.

Among the types of space weather, coronal mass ejections (CMEs) are the most dangerous. When these massive eruptions of plasma hit Earth’s magnetosphere, they can overwhelm it and cause geomagnetic storms.

The most powerful geomagnetic storm in recorded history is the Carrington Event of 1859, which caused widespread disruption to the telegraph system in the USA. It even sparked fires and injured some people. In today’s world, a similar event could cause catastrophic damage to our satellite systems and power grids.

Understanding the magnetic fields of the corona is crucial to predicting space weather events like CMEs. The DKIST’s ability to map these fields brings us one step closer to predicting dangerous solar storms before they reach Earth. This allows scientists to prepare satellites and power grids for the impacts of space weather, potentially saving billions of dollars in damages.

While this breakthrough in mapping the Sun’s magnetic fields is a huge leap for solar physics, its implications extend beyond our solar system. As NSO Director Christoph Keller explains, this is the beginning of a new era of astronomy that will help us understand how the magnetic fields of other stars affect planets, including those in the thousands of exoplanetary systems we now know exist.

Table 1: Space Weather Events and Their Effects

Table 2: Key Instruments in Solar Research

The groundbreaking work done by the Daniel K. Inouye Solar Telescope marks a new chapter in solar and astronomical research. For the first time, scientists have been able to map the magnetic fields of the Sun’s corona, allowing us to better understand the forces driving space weather.

References

• Solar Flares
• Coronal Mass Ejections
• Solar Wind
• DKIST Solar Telescope
• Science Advances Paper
• Bohr Magneton
• Carrington Event

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