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Posts Tagged ‘solar magnetic field’

Artificial Intelligence Helps Stanford Physicists Predict Dangerous Solar Flares

January 15, 2015 Leave a comment

Credit: NASA/SDO and the AIA; EVE; and HMI science teams

Credit: NASA/SDO and the AIA; EVE; and HMI science teams

Solar flares can release the energy equivalent of many atomic bombs, enough to cut out satellite communications and damage power grids on Earth, 93 million miles away. The flares arise from twisted magnetic fields that occur all over the sun’s surface, and they increase in frequency every 11 years, a cycle that is now at its maximum.

Using artificial intelligence techniques, Stanford solar physicists Monica Bobra and Sebastien Couvidat have automated the analysis of the largest ever set of solar observations to forecast solar flares using data from the Solar Dynamics Observatory (SDO), which takes more data than any other satellite in NASA history. Their study identifies which features are most useful for predicting solar flares.

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Researchers Reveal Model Of Sun’s Magnetic Field


Image credit: NASA Solar Dynamics Observatory

Image credit: NASA Solar Dynamics Observatory

Researchers at the Universities of Leeds and Chicago have uncovered an important mechanism behind the generation of astrophysical magnetic fields such as that of the Sun.

Scientists have known since the 18th Century that the Sun regularly oscillates between periods of high and low solar activity in an 11-year cycle, but have been unable to fully explain how this cycle is generated.

In the ‘Information Age’, it has become increasingly important to be able to understand the Sun’s magnetic activity, as it is the changes in its magnetic field that are responsible for ‘space weather’ phenomena, including solar flares and coronal mass ejections. When this weather heads in the direction of Earth it can damage satellites, endanger astronauts on the International Space Station and cause power grid outages on the ground.

The research, published in the journal Nature, explains how the cyclical nature of these large-scale magnetic fields emerges, providing a solution to the mathematical equations governing fluids and electromagnetism for a large astrophysical body.

Full Story: http://www.leeds.ac.uk/news/article/3402/researchers_reveal_model_of_suns_magnetic_field

Researchers Explain Magnetic Field Misbehavior In Solar Flares: The Culprit Is Turbulence

May 28, 2013 2 comments

Credit: NASA/SDO

Credit: NASA/SDO

When a solar flare filled with charged particles erupts from the sun, its magnetic fields sometime break a widely accepted rule of physics. The flux-freezing theorem dictates that the magnetic lines of force should flow away in lock-step with the particles, whole and unbroken. Instead, the lines sometimes break apart and quickly reconnect in a way that has mystified astrophysicists.

But in a paper published in the May 23 issue of the journal Nature, an interdisciplinary research team led by a Johns Hopkins mathematical physicist says it has found a key to the mystery. The culprit, the group proposed, is turbulence—the same sort of violent disorder that can jostle a passenger jet when it occurs in the atmosphere. Using complex computer modeling to mimic what happens to magnetic fields when they encounter turbulence within a solar flare, the researchers built their case, explaining why the usual rule did not apply.

“The flux-freezing theorem often explains things beautifully,” said Gregory Eyink, a Department of Applied Mathematics and Statistics professor who was lead author of the Nature study. “But in other instances, it fails miserably. We wanted to figure out why this failure occurs.”

Full Story: http://releases.jhu.edu/2013/05/22/researchers-explain-magnetic-field-misbehavior-in-solar-flares-the-culprit-is-turbulence/

Magnetic Turbulence Trumps Collisions To Heat Solar Wind

August 17, 2012 Leave a comment

New research led by University of Warwick physicist Dr Kareem Osman has provided significant insight into how the solar wind heats up when it should not. The solar wind rushes outwards from the raging inferno that is our Sun, but from then on the wind should only get cooler as it expands beyond our solar system since there are no particle collisions to dissipate energy. However, the solar wind is surprisingly hotter than it should be, which has puzzled scientists for decades. Two new research papers led by Dr Osman may have solved that puzzle.

The new research led by Dr. Kareem Osman at the University of Warwick’s Centre for Fusion, Space and Astrophysics has revealed how turbulence heats the solar wind. He says:

“Turbulence stretches and bends magnetic field lines, and often two oppositely directed field lines can come together to form a current sheet. These current sheets, which are distributed randomly in space, could be sites where the magnetic field snaps and reconnects transferring energy to particle heating. There are also many more ways that current sheets can heat and accelerate the plasma.”

Full Story: http://www2.warwick.ac.uk/newsandevents/pressreleases/magnetic_turbulence_trumps#

Solar ‘Climate Change’ Could Cause Rougher Space Weather

March 29, 2012 1 comment

Recent research shows that the space age has coincided with a period of unusually high solar activity, called a grand maximum. Isotopes in ice sheets and tree rings tell us that this grand solar maximum is one of 24 during the last 9300 years and suggest the high levels of solar magnetic field seen over the space age will reduce in future. This decline will cause a reduction in sunspot numbers and explosive solar events, but those events that do take place could be more damaging. Graduate student Luke Barnard of the University of Reading will present new results on ‘solar climate change’ in his paper at the National Astronomy Meeting in Manchester.

The level of radiation in the space environment is of great interest to scientists and engineers as it poses various threats to man-made systems including damage to electronics on satellites. It can also be a health hazard to astronauts and to a lesser extent the crew of high-altitude aircraft.

The main sources of radiation are galactic cosmic rays (GCRs), which are a continuous flow of highly energetic particles from outside our solar system and solar energetic particles (SEPs), which are accelerated to high energies in short bursts by explosive events on the sun. The amount of radiation in the near-Earth environment from these two sources is partly controlled in a complicated way by the strength of the Sun’s magnetic field.

There are theoretical predictions supported by observational evidence that a decline in the average strength of the Sun’s magnetic field would lead to an increase in the amount of GCRs reaching near-Earth space. Furthermore there are predictions that, although a decline in solar activity would mean less frequent bursts of SEPs, the bursts that do occur would be larger and more harmful.

Full Story: http://www.jodrellbank.manchester.ac.uk/meetings/nam2012/pressreleases/nam12.html