Global Magnetic Field of the Solar Corona Measured for the First Time

Related Articles

Related Articles

An international team of solar physicists, including academics from Northumbria University, in Newcastle upon Tyne, has recently measured the global magnetic field of the outer most layer of the Sun’s atmosphere, the solar corona, for the first time.

The team, including researchers from Peking University, China and National Center for Atmospheric Research (NCAR), USA, used observations from the Coronal Multi-channel Polarimeter (CoMP), an instrument that can provide measurements of infrared radiation coming from the Sun’s atmosphere. Their research has just been published in the journal Science.

The Sun is a magnetized star, and its magnetic field plays a critical role in shaping the solar atmosphere. The magnetic field governs many aspects of the Sun’s behaviour, leading to an 11-year solar cycle, spectacular solar eruptions, and the heating of the hot gas (plasma) in the solar corona to millions of degrees Celsius.

 

The magnetic field threads through the different layers of the Sun’s atmosphere, which means that information on the magnetic field of the whole atmosphere is required in order to understand the interplay between the solar plasma and magnetic field.

However, up until now, routine measurements of the solar magnetic field have only been achieved at the surface of our star (the area of the Sun known as the photosphere).

While more than 100 years has passed since the first measurement of the Sun’s magnetic field, we still do not have a precise knowledge of the magnetic field in the upper solar atmosphere, especially the corona.

More than 20 years ago, a technique called magnetoseismology was put forward as a way to measure the magnetic field in the corona. This method makes use of magnetic waves, known as Alfvén waves, that are observed to travel along the magnetic fields.

Importantly, the speed the waves travel at depends on the strength of the magnetic field, meaning that being able to measure how fast they travel enables an estimate of the magnetic field to made.

Dr Richard Morton, a UKRI Future Leader Fellow working at Northumbria University, is a world expert in the observation and analysis of waves in the Sun’s corona and was part of the team which delivered these exciting results.

Dr Morton has been a long-term user of the CoMP instrument and advocate of using such measurements to study the Sun’s magnetic field. As he explains: “The data that is collected from CoMP reveals the Sun’s corona is full of these Alfvén waves and provides us with the best available view of them.”

The current research is built upon Dr Morton’s earlier works, which demonstrated the possibility the magnetic waves could be used as a tool (Morton et al., Nature Communications 2015, Long et al., Astronomy & Astrophysics, 2017).

“I think that this is a wonderful demonstration of how we can exploit the Alfvén waves to probe the properties of the Sun,” Dr Morton added, noting that, “the process is similar to how seismologists use earthquakes to find out what the interior of the Earth looks like.”

This is the first time that a global map of the coronal magnetic field has been obtained through actual coronal observations, thus marking a leap towards solving the problem of coronal magnetic field measurements.

In principle, with this technique, global coronal magnetic field maps could now be routinely obtained, filling in the missing part of the measurements of the Sun’s global magnetism. Together with simultaneously measured magnetic field measurements from the Sun’s surface, these synoptic coronal magnetograms will provide critical information to advance the understanding of how the magnetic field couples the different layers of the Sun’s atmosphere as well as the physical mechanisms responsible for solar eruptions and solar cycle.

Northumbria University

Header Image Credit : Yang et al. 2020, Science

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

The Great Wall of Gorgan

The Great Wall of Gorgan, also called the "The Red Snake" or “Alexander's Barrier” is the second-longest defensive wall (after the Great Wall of China), which ran for 121 miles from a narrowing between the Caspian Sea north of Gonbade Kavous (ancient Gorgan, or Jorjan in Arabic) and the Pishkamar mountains of north-eastern Iran.

Aelia Capitolina – Roman Jerusalem

Aelia Capitolina was a Roman colony, constructed after the siege of 70 AD during the First Jewish-Roman War, when the city of Jerusalem and the Second Temple on Temple Mount was destroyed.

Wild Birds as Offerings to the Egyptian Gods

Millions of ibis and birds of prey mummies, sacrificed to the Egyptian gods Horus, Ra or Thoth, have been discovered in the necropolises of the Nile Valley.

Karahundj – The Ancient Speaking Stones

Karahundj, also called Carahunge and Zorats Karer is an ancient stone complex, constructed on a mountain plateau in the Syunik Province of Armenia.

Palaeontologists Establish Spinosaurus Was Real Life ‘River Monster’

A discovery of more than a thousand dinosaur teeth, by a team of researchers from the University of Portsmouth, proves beyond reasonable doubt that Spinosaurus, the giant predator made famous by the movie Jurassic Park III as well as the BBC documentary Planet Dinosaur was an enormous river-monster.

Archaeology Uncovers Infectious Disease Spread – 4000 Years Ago

New bioarchaeology research from a University of Otago PhD candidate has shown how infectious diseases may have spread 4000 years ago, while highlighting the dangers of letting such diseases run rife.

Buhen – The Sunken Egyptian Fortress

Buhen was an ancient Egyptian settlement and fortress, located on the West bank of the Nile in present-day Sudan.

The Modhera Sun Temple

The Sun Temple is an ancient Hindu temple complex located on a latitude of 23.6° (near Tropic of Cancer) on the banks of the Pushpavati river at Modhera in Gujarat, India.

Popular stories

The Secret Hellfire Club and the Hellfire Caves

The Hellfire Club was an exclusive membership-based organisation for high-society rakes, that was first founded in London in 1718, by Philip, Duke of Wharton, and several of society's elites.

Port Royal – The Sodom of the New World

Port Royal, originally named Cagway was an English harbour town and base of operations for buccaneers and privateers (pirates) until the great earthquake of 1692.

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.

Did Corn Fuel Cahokia’s Rise?

A new study suggests that corn was the staple subsistence crop that allowed the pre-Columbian city of Cahokia to rise to prominence and flourish for nearly 300 years.