Scientists explain mystery of observed turbulent density fluctuations in interplanetary space

Oct 28, 2009 by Ray Garner

( -- Scientists at The University of Alabama in Huntsville have developed a three-dimensional simulation model to understand behavior of interplanetary charged particles in space.

Physics professors Dastgeer Shaikh and Gary Zank of the university's Center for Space Plasma and Aeronomic Research and Department of Physics said the model explains how density of the interplanetary particles varies in time and space. Remarkably, the distribution of scale sizes of the density fluctuations is observed to satisfy a universal law called the Kolmogorov-spectrum.

The researchers noted that interplanetary space surrounding Earth is filled up by randomly moving charged and uncharged particles. These particles originate essentially from stars like our Sun or other nearby stars and are accelerated through interplanetary space. These are real "micro-probes" that tell us about distance, composition and many important aspects of the distant cosmological objects such as neighboring stars, galaxies and massive astrophysical clouds.

"From the behavior of these particles in space, it is possible to know the extent of the physical ," they explained. "We provide a simpler explanation of why should particle density follow a Kolmogorov-spectrum. The interplanetary space is like water or air surrounding us. The charged particles are tied to the mass-less rope of lines and move around in water in a random manner. Something similar to "cream in a cup of coffee" or particles of 'baby talcum powder' spread on the surface of stirred water that convects the particles of powder along with the water flow. We find that these particles follow a Kolmogorov-spectrum. We are trying to understand their motion statistically."

NASA's Voyager 2 spacecraft, cruising in the outer space for nearly 30 years, has tracked down the interplanetary particle density from our Sun to a distance up to 100 times the distance between the Sun and Earth. That is 93.7 million miles multiplied by 100. "It was found that the particle density varies with distance by a Kolmogorov-spectrum. But one of the major hurdles in understanding this spectrum is interplanetary turbulence that makes the particle's trajectory random in space and time," the scientists said.

The original theoretical effort behind this model was laid down in early 1990s by Dr. Zank, who had put forward "a truly amazing hypothesis" that related the density to velocity of these turbulent particles, according to Dr. Shaikh. "It took us nearly 20 years to computationally realize the truth behind Zank's model. We run our higher resolution computational model on San Diego supercomputer (256 processors) to arrive at this conclusion. Our model is also consistent with Voyager's observations."

Drs. Zank and Shaikh said it's important to know correct statistical behavior of the interplanetary particle density. "Some of the techniques (like angular broadening) are based on density variations to measure the distance of stellar objects from Earth. Precise measurement of density field is critical to determine exact location, age, and composition of the stellar bodies," they said.

Their research will appear in the November issue of the Royal Astronomical Society's journal.

More information: "The turbulent density spectrum in the solar wind plasma", ref. MN-09-0751-MJ.R4, has been accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal.

Provided by University of Alabama in Huntsville (news : web)

Explore further: Thermonuclear X-ray bursts on neutron stars set speed record

add to favorites email to friend print save as pdf

Related Stories

Explaining the Mystery of the Voyager

Feb 27, 2009

With a new 3D-model for energy simulation scientists from Bochum, Germany, and Huntsville, USA, are studying the 'physical mystery' of the Voyager. Over 30 years ago the spacecraft detected particles in solar wind which were ...

Magnetic fields get reconnected in turbulent plasma too

Mar 27, 2007

Using measurements of the four ESA's Cluster satellites, a study published this week in Nature Physics shows pioneering experimental evidence of magnetic reconnection also in turbulent 'plasma' around Earth.

Space Probes Detect Enormous Natural Particle Accelerator

Jan 12, 2006

A fleet of NASA and ESA space-weather probes observed an immense jet of electrically charged particles in the solar wind between the Sun and Earth. The jet, at least 200 times as wide as the Earth, was powered ...

Simple Explanation for Mysterious Observations

Aug 18, 2009

Recently, several astronomical experiments have revealed mysterious components of elementary particles. But up until now, the origin of electrons and positrons is unknown. Is dark matter the actual origin of this radiation, ...

Recommended for you

How can we find tiny particles in exoplanet atmospheres?

Aug 29, 2014

It may seem like magic, but astronomers have worked out a scheme that will allow them to detect and measure particles ten times smaller than the width of a human hair, even at many light-years distance.  ...

Spitzer telescope witnesses asteroid smashup

Aug 28, 2014

( —NASA's Spitzer Space Telescope has spotted an eruption of dust around a young star, possibly the result of a smashup between large asteroids. This type of collision can eventually lead to the ...

Witnessing the early growth of a giant

Aug 27, 2014

Astronomers have uncovered for the first time the earliest stages of a massive galaxy forming in the young Universe. The discovery was made possible through combining observations from the NASA/ESA Hubble ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

2.7 / 5 (3) Oct 28, 2009
Interplanetary Space Surrounding Earth . . .

Is continuously altered by the Sun itself. All nine planets glide through the heliosphere.

Turbulence is induced in this outer layer of the Sun by magnetic storms. These energetic events may transfer tons of high-energy particles directly to Earth.

See: "Magnetic Portals Connect Sun and Earth" NASA Headline News (30 Oct 2008).

With kind regards,
Oliver K. Manuel
5 / 5 (1) Oct 28, 2009
"100 times the distance between the Sun and Earth. That is 93.7 million miles multiplied by 100"

Finally Physorg decides to include a reasonable sounding measurement. Usually they say something retarded like "3 football fields" or "one hundred times smaller than a human hair".

Thank you for finally managing to say something intelligent, physorg.