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.
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 Daniel K. Inouye Solar Telescope is located on the island of Maui in Hawai’i. It was built by the National Science Foundation (NSF). This telescope has a mirror that is four meters wide. It is the biggest telescope in the world designed for studying the Sun. The image is credited to the National Solar Observatory.
The key to this breakthrough lies in theZeeman 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.
This image uses false colours to better show the Sun’s layers. Solar prominences often come before coronal mass ejections (CMEs), although not every prominence escapes the Sun’s outer layer (the corona). Some stay within the corona and never become CMEs. Image Credit: By Kelvinsong – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=23371669
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.
This figure shows some of the results from the research. The top part of the image is from the Solar Dynamics Observatory and its Atmospheric Image Assembly. The bottom part of the image is from DKIST. The black dotted lines represent solar radii, which are measurements of the distance from the center of the Sun to its outer surface. Both images show that inside the dense structures of the Sun’s corona, the polarization amplitude becomes stronger. Polarization amplitude refers to the strength of the light’s wave orientation as it moves through these structures. ?B refers to the Bohr magneton. This is a way to measure how strong a magnetic field is. DN/s stands for Data Numbers per second, which is a way to track how solar activity changes over time. Image Credit: Schad et al. 2024.
The most powerful geomagnetic storm in recorded history is theCarrington 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.
The overplotted lines in this figure from the research indicate the direction of linear polarization in the Sun’s outer atmosphere, called the corona. Linear polarization refers to how light waves move in a specific direction or pattern. The scale on the right shows the percentage of light that is polarized by the magnetic fields in the corona. Polarization amplitude means the strength or intensity of the polarization. Image Credit: Schad et al. 2024.
Measures magnetic fields, velocities, and intensities in the corona
Coronagraph
Creates artificial solar eclipses to observe the faint corona
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.
