Scientist explores a better way to predict space weather

October 22, 2018, Southwest Research Institute
A Southwest Research Institute space scientist shed new light on predicting the thermodynamics of solar flares and other “space weather” events involving hot, fast-moving plasmas, such as those depicted in this illustration. The Kappa equation calculates the distribution of particle velocities at thermal equilibrium when streams of fast-moving particles are moving en masse, typical of space plasma particle systems. Credit: NASA

Findings recently published by a Southwest Research Institute (SwRI) space scientist shed new light on predicting the thermodynamics of solar flares and other "space weather" events involving hot, fast-moving plasmas.

The science of statistical mechanics is one of the pillars of understanding the thermodynamic behavior of phenomena with a large number of , such as gases. Classical statistical methods have stood the test of time for describing Earth-bound systems, such as the relatively dense mix of gases that makes up our air, explains Dr. George Livadiotis, a senior research scientist in SwRI's Space Science and Engineering Division.

At thermal equilibrium, where heat energy is transferred equally among gas particles, their distribution falls into a predictable ratio—lots of low-velocity particles to only a few fast ones. The particles move chaotically, colliding with each other frequently. A statistical equation, known as a Maxwell-Boltzmann or Maxwellian distribution, accurately characterizes how this mix of particles of different speeds will be distributed on Earth.

However, Livadiotis says, things are different in space, which is actually not empty but filled with plasma, the so-called fourth state of matter. Plasma consists of electrically charged particles—it's neither gas, liquid nor solid, although it often behaves like a gas.

Space plasma like the that flows outward from the Sun has a higher ratio of fast-moving particles. Unlike gases on Earth, they are "correlated," mostly moving in the same direction so they experience fewer collisions with each other. For this set of circumstances, the Maxwellian distribution model no longer works well. Livadiotis has confirmed that a separate statistical equation, called "Kappa," is more applicable for space phenomena.

Kappa is the mathematical equation that describes the distribution of particle velocities at thermal equilibrium when there are correlations among particle velocities, as is typical for collision-less space particle systems.

"The Kappa equation calculates the distribution of particle velocities at when streams of fast-moving particles are moving en masse," he said. "That is the typical situation for particle systems such as space plasmas."

Kappa not only predicts space plasma particle distributions better, but also characterizes their thermodynamic behavior better than the Maxwellian model, Livadiotis says. This relates to what happens when extremely hot solar wind crashes into Earth's protective blanket of magnetically charged particles, known as the magnetosphere.

"Kappa distributions allowed scientists to make the first temperature measurements of the outer heliosphere," Livadiotis says. "With Kappa, we can dramatically improve our understanding of the nature and properties of matter, whether it is the solar wind, flares and coronal mass ejections, or rare and more extreme phenomena like cosmic rays."

His paper, "Thermodynamic Origin of Kappa Distributions," is published in the June 18, 2018, edition of EPL, a letters journal exploring the frontiers of physics.

Explore further: Wave-particle interactions allow collision-free energy transfer in space plasma

More information: George Livadiotis. Thermodynamic origin of kappa distributions, EPL (Europhysics Letters) (2018). DOI: 10.1209/0295-5075/122/50001

Related Stories

Cosmic bow shocks

March 7, 2018

Imagine an object moving at super-sonic speed. This object, as it moves through a medium, causes the material in the medium to pile up, compress, and heat up. The result is a type of shock wave, known as a bow shock.

Image: Aurora observed from orbit

August 16, 2018

Ever wondered what auroras look like from space? Astronaut Alexander Gerst, also known as @Astro_Alex, gives us his bird's-eye view from aboard the International Space Station, tweeting that the experience is "[m]ind-blowing, ...

Ripples in space key to understanding cosmic rays

October 17, 2016

In a new study researchers at the Swedish Institute of Space Physics have used measurements from NASA's MMS (Magnetospheric MultiScale) satellites to reveal that there are ripples, or surface waves, moving along the surface ...

Studying magnetic space explosions with NASA missions

March 9, 2017

Every day, invisible magnetic explosions are happening around Earth, on the surface of the sun and across the universe. These explosions, known as magnetic reconnection, occur when magnetic field lines cross, releasing stored ...

Recommended for you

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

The friendly extortioner takes it all

February 15, 2019

Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.