From NASA Goddard Space Flight Center: Women in STEM “Unexpected Rain on Sun Links Two Solar Mysteries” Emily Mason

NASA Goddard Banner
From NASA Goddard Space Flight Center

April 5, 2019

Miles Hatfield
NASA’s Goddard Space Flight Center, Greenbelt, Md.

For five months in mid 2017, Emily Mason did the same thing every day. Arriving to her office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, she sat at her desk, opened up her computer, and stared at images of the Sun — all day, every day. “I probably looked through three or five years’ worth of data,” Mason estimated. Then, in October 2017, she stopped. She realized she had been looking at the wrong thing all along.

Mason, a graduate student at The Catholic University of America in Washington, D.C., was searching for coronal rain: giant globs of plasma, or electrified gas, that drip from the Sun’s outer atmosphere back to its surface. But she expected to find it in helmet streamers, the million-mile tall magnetic loops — named for their resemblance to a knight’s pointy helmet — that can be seen protruding from the Sun during a solar eclipse. Computer simulations predicted the coronal rain could be found there. Observations of the solar wind, the gas escaping from the Sun and out into space, hinted that the rain might be happening. And if she could just find it, the underlying rain-making physics would have major implications for the 70-year-old mystery of why the Sun’s outer atmosphere, known as the corona, is so much hotter than its surface. But after nearly half a year of searching, Mason just couldn’t find it. “It was a lot of looking,” Mason said, “for something that never ultimately happened.”

Mason searched for coronal rain in helmet streamers like the one that appears on the left side of this image, taken during the 1994 eclipse as viewed from South America. A smaller pseudostreamer appears on the western limb (right side of image). Named for their resemblance to a knight’s pointy helmet, helmet streamers extend far into the Sun’s faint corona and are most readily seen when the light from the Sun’s bright surface is occluded. Credits: © 1994 Úpice observatory and Vojtech Rušin, © 2007 Miloslav Druckmüller

The problem, it turned out, wasn’t what she was looking for, but where. In a paper published today in The Astrophysical Journal Letters, Mason and her coauthors describe the first observations of coronal rain in a smaller, previously overlooked kind of magnetic loop on the Sun. After a long, winding search in the wrong direction, the findings forge a new link between the anomalous heating of the corona and the source of the slow solar wind — two of the biggest mysteries facing solar science today.

How It Rains on the Sun

Observed through the high-resolution telescopes mounted on NASA’s SDO spacecraft, the Sun – a hot ball of plasma, teeming with magnetic field lines traced by giant, fiery loops — seems to have few physical similarities with Earth.


But our home planet provides a few useful guides in parsing the Sun’s chaotic tumult: among them, rain.

On Earth, rain is just one part of the larger water cycle, an endless tug-of-war between the push of heat and pull of gravity. It begins when liquid water, pooled on the planet’s surface in oceans, lakes, or streams, is heated by the Sun. Some of it evaporates and rises into the atmosphere, where it cools and condenses into clouds. Eventually, those clouds become heavy enough that gravity’s pull becomes irresistible and the water falls back to Earth as rain, before the process starts anew.

On the Sun, Mason said, coronal rain works similarly, “but instead of 60-degree water you’re dealing with a million-degree plasma.” Plasma, an electrically-charged gas, doesn’t pool like water, but instead traces the magnetic loops that emerge from the Sun’s surface like a rollercoaster on tracks.

Coronal rain, like that shown in this movie from NASA’s SDO in 2012, is sometimes observed after solar eruptions, when the intense heating associated with a solar flare abruptly cuts off after the eruption and the remaining plasma cools and falls back to the solar surface. Mason was searching for coronal rain not associated with eruptions, but instead caused by a cyclical process of heating and cooling similar to the water cycle on Earth.
Credits: NASA’s Solar Dynamics Observatory/Scientific Visualization Studio/Tom Bridgman, Lead Animator

At the loop’s foot points, where it attaches to the Sun’s surface, the plasma is superheated from a few thousand to over 1.8 million degrees Fahrenheit. It then expands up the loop and gathers at its peak, far from the heat source. As the plasma cools, it condenses and gravity lures it down the loop’s legs as coronal rain.

Mason was looking for coronal rain in helmet streamers, but her motivation for looking there had more to do with this underlying heating and cooling cycle than the rain itself. Since at least the mid-1990s, scientists have known that helmet streamers are one source of the slow solar wind, a comparatively slow, dense stream of gas that escapes the Sun separately from its fast-moving counterpart. But measurements of the slow solar wind gas revealed that it had once been heated to an extreme degree before cooling and escaping the Sun. The cyclical process of heating and cooling behind coronal rain, if it was happening inside the helmet streamers, would be one piece of the puzzle.

The other reason connects to the coronal heating problem — the mystery of how and why the Sun’s outer atmosphere is some 300 times hotter than its surface. Strikingly, simulations have shown that coronal rain only forms when heat is applied to the very bottom of the loop. “If a loop has coronal rain on it, that means that the bottom 10% of it, or less, is where coronal heating is happening,” said Mason. Raining loops provide a measuring rod, a cutoff point to determine where the corona gets heated. Starting their search in the largest loops they could find — giant helmet streamers — seemed like a modest goal, and one that would maximize their chances of success.

She had the best data for the job: Images taken by NASA’s Solar Dynamics Observatory, or SDO, a spacecraft that has photographed the Sun every twelve seconds since its launch in 2010. But nearly half a year into the search, Mason still hadn’t observed a single drop of rain in a helmet streamer. She had, however, noticed a slew of tiny magnetic structures, ones she wasn’t familiar with. “They were really bright and they kept drawing my eye,” said Mason. “When I finally took a look at them, sure enough they had tens of hours of rain at a time.”

At first, Mason was so focused on her helmet streamer quest that she made nothing of the observations. “She came to group meeting and said, ‘I never found it — I see it all the time in these other structures, but they’re not helmet streamers,’” said Nicholeen Viall, a solar scientist at Goddard, and a coauthor of the paper. “And I said, ‘Wait…hold on. Where do you see it? I don’t think anybody’s ever seen that before!’”

A Measuring Rod for Heating

These structures differed from helmet streamers in several ways. But the most striking thing about them was their size.

“These loops were much smaller than what we were looking for,” said Spiro Antiochos, who is also a solar physicist at Goddard and a coauthor of the paper. “So that tells you that the heating of the corona is much more localized than we were thinking.”

Mason’s article analyzed three observations of Raining Null-Point Topologies, or RNTPs, a previously overlooked magnetic structure shown here in two wavelengths of extreme ultraviolet light. The coronal rain observed in these comparatively small magnetic loops suggests that the corona may be heated within a far more restricted region than previously expected. Credits: NASA’s Solar Dynamics Observatory/Emily Mason

While the findings don’t say exactly how the corona is heated, “they do push down the floor of where coronal heating could happen,” said Mason. She had found raining loops that were some 30,000 miles high, a mere two percent the height of some of the helmet streamers she was originally looking for. And the rain condenses the region where the key coronal heating can be happening. “We still don’t know exactly what’s heating the corona, but we know it has to happen in this layer,” said Mason.

A New Source for the Slow Solar Wind

But one part of the observations didn’t jibe with previous theories. According to the current understanding, coronal rain only forms on closed loops, where the plasma can gather and cool without any means of escape. But as Mason sifted through the data, she found cases where rain was forming on open magnetic field lines. Anchored to the Sun at only one end, the other end of these open field lines fed out into space, and plasma there could escape into the solar wind. To explain the anomaly, Mason and the team developed an alternative explanation — one that connected rain on these tiny magnetic structures to the origins of the slow solar wind.

In the new explanation, the raining plasma begins its journey on a closed loop, but switches — through a process known as magnetic reconnection — to an open one. The phenomenon happens frequently on the Sun, when a closed loop bumps into an open field line and the system rewires itself. Suddenly, the superheated plasma on the closed loop finds itself on an open field line, like a train that has switched tracks. Some of that plasma will rapidly expand, cool down, and fall back to the Sun as coronal rain. But other parts of it will escape – forming, they suspect, one part of the slow solar wind.

Mason is currently working on a computer simulation of the new explanation, but she also hopes that soon-to-come observational evidence may confirm it. Now that Parker Solar Probe, launched in 2018, is traveling closer to the Sun than any spacecraft before it, it can fly through bursts of slow solar wind that can be traced back to the Sun — potentially, to one of Mason’s coronal rain events.

NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker

After observing coronal rain on an open field line, the outgoing plasma, escaping to the solar wind, would normally be lost to posterity. But no longer. “Potentially we can make that connection with Parker Solar Probe and say, that was it,” said Viall.

Digging Through the Data

As for finding coronal rain in helmet streamers? The search continues. The simulations are clear: the rain should be there. “Maybe it’s so small you can’t see it?” said Antiochos. “We really don’t know.”

But then again, if Mason had found what she was looking for she might not have made the discovery — or have spent all that time learning the ins and outs of solar data.

“It sounds like a slog, but honestly it’s my favorite thing,” said Mason. “I mean that’s why we built something that takes that many images of the Sun: So we can look at them and figure it out.”


IRIS Spots Plasma Rain on Sun’s Surface

NASA IRIS spacecraft, a spacecraft that takes spectra in three passbands, allowing us to probe different layers of the solar atmosphere

And the Blobs Just Keep on Coming

See the full article here.


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

NASA/Goddard Campus

#astronomy, #astrophysics, #basic-research, #coronal-rain, #cosmology, #emily-mason, #helmet-streamers, #magnetic-reconnection, #nasa-goddard-space-flight-center, #sdo-nasas-solar-dynamics-observatory, #solar-research, #women-in-stem

From Science News: “Merging magnetic blobs fuel the sun’s huge plasma eruptions”

From Science News

March 7, 2019
Lisa Grossman

Before coronal mass ejections, plasma shoots up, breaks apart and then comes together again.

BURSTING WITH PLASMA Solar scientists have long wondered what drives big bursts of plasma called coronal mass ejections. New analysis of an old eruption suggests the driving force might be merging magnetic blobs.

Solar plasma eruptions are the sum of many parts, a new look at a 2013 coronal mass ejection shows.

These bright, energetic bursts happen when loops of magnetism in the sun’s wispy atmosphere, or corona, suddenly snap and send plasma and charged particles hurtling through space (SN Online: 8/16/17).

But it was unclear how coronal mass ejections, or CMEs, get started. One theory suggests that a twisted tube of magnetic field lines called a flux rope hangs out on the solar surface for hours or days before a sudden perturbation sends it expanding off the solar surface.

Another idea is that the sun’s magnetic field lines are forced so close together that the lines break and recombine with each other. The energy of that magnetic reconnection forms a short-lived flux rope that quickly erupts.

“We do not know which comes first,” the flux rope or the reconnection, says solar physicist Bernhard Kliem of the University of Potsdam in Germany.

Kliem and his colleagues scrutinized a CME recorded on May 13, 2013, by NASA’s Solar Dynamics Observatory.


They found that before it erupted, a vertical sheet of plasma split into blobs, marking breaking and merging magnetic field lines. Over about half an hour, the blobs shot upward and merged into a large flux rope, which briefly arced over the solar surface before erupting into space. That quick growth supports the idea that CMEs grow through magnetic reconnection, the team, led by Tingyu Gou and Rui Liu of the University of Science and Technology of China in Hefei, reports March 6 in Science Advances.

“This was actually surprising, that this reconnection was rather fast,” Kliem says. That speedy setup might make it more difficult to predict when CMEs are about to occur. That’s too bad because, when aimed at Earth, these bursts cause auroras and can knock out power grids and damage satellites.

A STAR’S CME IS BORN The sun’s coronal mass ejections seem to result from many small plasma blobs combining. In this video, enhanced data from NASA’s Solar Dynamics Observatory shows a vertical sheet of plasma suddenly break into blobs at about 17 seconds. Shortly after, the blobs rearrange themselves into a loop, and the loop bursts off the sun’s surface. At 30 seconds, more distant observations from the SOHO telescope show the CME’s progress. (A second, unrelated CME erupts off the right side of the sun near the video’s end.)

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

#astronomy, #astrophysics, #basic-research, #bernhard-kliem-of-the-university-of-potsdam-in-germany-and-his-colleagues-scrutinized-a-cme-recorded-on-may-13-2013-by-nasas-solar-dynamics-observatory, #but-it-was-unclear-how-coronal-mass-ejections-or-cmes-get-started, #cmes-coronal-mass-ejections, #cosmology, #magnetic-reconnection, #over-about-half-an-hour-the-blobs-shot-upward-and-merged-into-a-large-flux-rope-which-briefly-arced-over-the-solar-surface-before-erupting-into-space, #science-news, #solar-plasma-eruptions-are-the-sum-of-many-parts-a-new-look-at-a-2013-coronal-mass-ejection-shows, #solar-research, #solar-scientists-have-long-wondered-what-drives-big-bursts-of-plasma-called-coronal-mass-ejections-new-analysis-of-an-old-eruption-suggests-the-driving-force-might-be-merging-magnetic-blobs, #that-quick-growth-supports-the-idea-that-cmes-grow-through-magnetic-reconnection, #that-speedy-setup-might-make-it-more-difficult-to-predict-when-cmes-are-about-to-occur, #the-team-led-by-tingyu-gou-and-rui-liu-of-the-university-of-science-and-technology-of-china-in-hefei, #they-found-that-before-it-erupted-a-vertical-sheet-of-plasma-split-into-blobs-marking-breaking-and-merging-magnetic-field-lines

From NASA Goddard Space Flight Center: “Discovering Bonus Science With NASA’s Magnetospheric Multiscale Spacecraft”

NASA Goddard Banner
From NASA Goddard Space Flight Center

Illustration of MMS spacecraft. Credit: NASA

March 7, 2019

Mara Johnson-Groh
NASA’s Goddard Space Flight Center, Greenbelt, Md.

NASA/MMS prior to launch

NASA MMS satellites in space. Credit: NASA

The four Magnetospheric Multiscale spacecraft are flying out of their element. The spacecraft have just completed a short detour from their routine science — looking at processes within Earth’s magnetic environment — and instead ventured outside it, studying something they were not originally designed for.

For three weeks, MMS studied the solar wind — the stream of supersonic charged particles flung around the solar system by the Sun — to better understand what’s known as turbulence in plasmas, the heated, electrified gases that make up 99 percent of ordinary matter in the universe. Turbulence is the chaotic motion of a fluid. It shows up in daily life everywhere from eddies in a river to smoke from a chimney, but it is incredibly hard to study because it’s so unpredictable and it remains one of the least well understood disciplines in all of physics. The mini-campaign will provide scientists with an up close and in-situ view to push the frontiers of the field.

But to take these groundbreaking measurements, MMS had to operate in an entirely new way — and MMS scientists and engineers designed a clever way to allow the spacecraft to study the solar wind with unprecedented accuracy, testing the limits and versatilities of MMS’ capabilities.

Opening New Doors

The Magnetospheric Multiscale mission, MMS, was launched in 2015 to study magnetic reconnection — the explosive snapping and forging of magnetic field lines, which flings high-energy particles around Earth.

NASA Magnetic reconnection, Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA

NASA TRACE spacecraft (1998-2010)

MMS was built with state-of-the-art instruments that take measurements with nearly 100 times better resolution than previous instruments. After two years of studying magnetic reconnection in Earth’s magnetic environment — the magnetosphere — on the dayside, MMS elongated its orbit to begin looking at reconnection behind Earth, away from the Sun, where it’s thought to spark the auroras.

Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase

Since MMS has completed its original mission goals, it’s now taking time in its extended mission to tackle some new science objectives. Understanding turbulence, which is one of NASA’s prime science objectives, is the first mini-campaign MMS plans to undertake.

“We would like to make a lot of these mini-campaigns in the future if this one is successful, which it’s already shaping up to be,” said Bob Ergun, researcher at the Laboratory for Atmospheric and Space Physics in Boulder, Colorado, who heads the new campaign. “MMS is a very, very powerful observatory with incredibly sensitive instruments on it and we’re trying to maximize their use to study these other priority sciences.”

Thinking Outside of the Magnetosphere

Studying the solar wind is best done from in the solar wind, but most of the time, the four MMS spacecraft orbit within or on the edge of Earth’s magnetosphere — where the magnetic field creates a buffer that protects the spacecraft from the solar wind.

Occasionally, however, routine orbital adjustments, used to maintain MMS’ elongated orbit, take it well outside. This year, a boost to the spacecraft orbit is taking MMS entirely out of Earth’s magnetic environment and past the bow shock — a region where the supersonic solar wind slams into Earth’s magnetosphere.

ESA Earth’s Bow shock

At such a distance, MMS passes through the solar wind itself, which allows a window of time to study the region’s turbulence.

Studying the solar wind is nothing like studying magnetic reconnection, but can be done with the same instruments that measure magnetic and electric fields. MMS is equipped with some of the most precise instruments ever flown in space, but in order to use them to study the solar wind, some adjustments first need to be made.

This infographic compares the four MMS spacecraft’s normal orientation and formation to the orientation and formation for the mission’s first mini-campaign to study turbulence in the solar wind. Credits: NASA’s Goddard Space Flight Center/Mary Pat Hrybyk-Keith

Normally MMS flies in a pyramid-shaped formation called a tetrahedron, which allows all four spacecraft to be equally separated. As they flew through the solar wind, the spacecraft were instead arranged in what scientists call a “string of pearls.” Flying perpendicular to the wind, the spacecraft followed one after another, each offset at distances of 25 to 100 kilometers (about 15.5 to 62 miles) from their neighbor. This allows scientists to see how much the solar wind varies over different distances.

However, as the spacecraft travel through the supersonic solar wind they create a wake behind them, just like a boat. This wake is not a natural feature in the solar wind, so the MMS scientists want to avoid having their instruments, which spin at the end of long booms, dragged through it. To make precise measurements unencumbered by the wake, the spacecraft were each tilted up 15 degrees. The tilt lifts the spinning booms up from travelling behind the spacecraft through the wake.

This angle allows scientists to get better data, but it comes with a cost. As a result of the tilt, the solar array doesn’t get as much light, meaning the spacecraft’s power is reduced by a few watts each. The tilt also puts thermal stress on the spacecraft, since the top of each gets hotter than the bottom. For a short campaign however, these effects won’t permanently affect the spacecraft.

Old Spacecraft, New Tricks

The data MMS gathered in this campaign will be some of the most accurate measurements of turbulence in the solar wind ever made. The research will also complement the work being done by NASA’s Parker Solar Probe, which flies through the Sun’s atmosphere studying the origins of the solar wind. While Parker Solar Probe measures the initial turbulence in the solar wind, MMS measured the aftermath when it reaches Earth.

“Almost all of the astrophysical plasmas we look at around the Sun, stars, black holes, accretion disks, jets, are all extremely turbulent, so by understanding it around Earth we understand it elsewhere,” Ergun said.

Ultimately this mini-campaign will also serve as a test case for what MMS is capable of doing in the future. Learning the nuances of MMS’ formations and tilt angles will allow the scientists to better understand MMS’s range of abilities, which may open the door up for other types of scientific campaigns as well.

Related Links

Learn more about NASA’s MMS Mission
NASA’s MMS Breaks Guinness World Record

See the full article here.


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

NASA/Goddard Campus

#discovering-bonus-science-with-nasas-magnetospheric-multiscale-spacecraft, #as-they-flew-through-the-solar-wind-the-spacecraft-were-instead-arranged-in-what-scientists-call-a-string-of-pearls, #astronomy, #astrophysics, #we-would-like-to-make-a-lot-of-these-mini-campaigns-in-the-future-if-this-one-is-successful-which-its-already-shaping-up-to-be-said-bob-ergun, #basic-research, #cosmology, #flying-perpendicular-to-the-wind-the-spacecraft-followed-one-after-another-each-offset-at-distances-of-25-to-100-kilometers-about-15-5-to-62-miles-from-their-neighbor, #magnetic-reconnection, #mms-is-equipped-with-some-of-the-most-precise-instruments-ever-flown-in-space-but-in-order-to-use-them-to-study-the-solar-wind-some-adjustments-first-need-to-be-made, #nasa-goddard-space-flight-center, #normally-mms-flies-in-a-pyramid-shaped-formation-called-a-tetrahedron-which-allows-all-four-spacecraft-to-be-equally-separated, #studying-the-solar-wind-is-nothing-like-studying-magnetic-reconnection-but-can-be-done-with-the-same-instruments-that-measure-magnetic-and-electric-fields, #the-data-mms-gathered-in-this-campaign-will-be-some-of-the-most-accurate-measurements-of-turbulence-in-the-solar-wind-ever-made, #the-research-will-also-complement-the-work-being-done-by-nasas-parker-solar-probe, #this-allows-scientists-to-see-how-much-the-solar-wind-varies-over-different-distances

From COSMOS Magazine: “Mechanics of coronal mass ejections revealed”

Cosmos Magazine bloc

From COSMOS Magazine

07 March 2019
Lauren Fuge

A coronal mass ejection captured by NASA’s Solar Dynamics Observatory in September, 2017. NASA/SDO.


An international team of astronomers has untangled new insight into the birth of coronal mass ejections, the most massive and destructive explosions from the sun.

In a paper published in the journal Science Advances, a team led by Tingyu Gou from the University of Science and Technology of China was able to clearly observe the onset and evolution of a major solar eruption for the first time.

From a distance the sun seems benevolent and life-giving, but on closer inspection it is seething with powerful fury. Its outer layer – the corona – is a hot and wildly energetic place that constantly sends out streams of charged particles in great gusts of solar wind.

It also emits localised flashes known as flares, as well as enormous explosions of billions of tons of magnetised plasma called coronal mass ejections (CMEs).

These eruptions could potentially have a big effect on Earth. CMEs can damage satellite electronics, kill astronauts on space walks, and cause magnetic storms that can disrupt electricity grids.

Studying CMEs is key to improving the capability to forecast them, and yet, for decades, their origin and evolution have remained elusive.

“The underlying physics is a disruption of the coronal magnetic field,” explains Bernhard Kliem, co-author on the paper, from the University of Potsdam in Germany.

Such a disruption allows an expanding bubble of plasma – a CME – to build up, driving it and the magnetic field upwards. The “bubble” can tear off and erupt, often accompanied by solar flares.

The magnetic field lines then fall back and combine with neighbouring lines to form a less-stressed field, creating the beautiful loops seen in many UV and X-ray images of the sun.

“This breaking and re-closing process is called magnetic reconnection, and it is of great interest in plasma physics, astrophysics, and space physics,” says Kliem.

NASA Magnetic reconnection, Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA

NASA TRACE spacecraft (1998-2010)

But the reason why the coronal magnetic field is disturbed at all is a matter of continuing debate.

“To many, an instability of the magnetic field is the primary reason,” says Kliem. “This requires the magnetic field to form a twisted flux tube, known as magnetic flux rope, where the energy to be released in the eruption can be stored.”

The theory holds that turbulence causes the magnetic flux ropes to become tangled and unstable, and if they suddenly rearrange themselves in the process of magnetic reconnection, they can release the trapped energy and trigger a CME.

Others in the field think that it’s the other way around – magnetic reconnection is the trigger that forms the flux rope in the first place.

It’s a tricky question to tease out because flux ropes and reconnection are so intertwined. Recent studies [Nature] even suggest that there’s another layer of complexity: smaller magnetic loops called mini flux ropes, or plasmoids, which continuously form in a fractal-like fashion and may have a cascading influence on bigger events like a CME.

To get a better handle on this complex process, the team observed the evolution of a CME that erupted on May 13, 2013. By combining multi-wavelength data from NASA’s Solar Dynamics Observatory (SDO) with modern analysis techniques, they were able to determine the correct sequence of events: that a magnetic reconnection in the solar corona formed the flux rope, which then became unstable and erupted.

Specifically, they found that the CME bubble continuously evolved from mini flux ropes, bridging the gap between micro- and macro-scale dynamics and thus illuminating a complete evolutionary path of CMEs.

The next step, Kliem says, is to understand another important phenomenon in the eruption process: a thin, elongated structure known as a “current sheet”, in which the mini flux ropes were formed.

“We need to study when and where the coronal magnetic field forms such current sheets that can build up a flux rope, which then, in turn, can erupt to drive a solar eruption,” he concludes.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

#astronomy, #astrophysics, #basic-research, #cmes-coronal-mass-ejections, #cosmology, #cosmos, #magnetic-reconnection, #solar-research

From PPPL: “Experiments at PPPL show remarkable agreement with satellite sightings”


December 7, 2018
John Greenwald

Members of the MRX team with the device in the background. From left, Masaaki Yamada, Jongsoo Yoo, Jonathan Jara-Almonte, Will Fox, and Hantao Ji.
(Photo by Elle Starkman/PPPL Office of Communications)

Illustration of the MMS spacecraft in orbit in Earth’s magnetic field. NASA

As on Earth, so in space. A four-satellite mission that is studying magnetic reconnection — the breaking apart and explosive reconnection of the magnetic field lines in plasma that occurs throughout the universe — has found key aspects of the process in space to be strikingly similar to those found in experiments at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL). The similarities show how the studies complement each other: The laboratory captures important global features of reconnection and the spacecraft documents local key properties as they occur.

NASA Magnetic reconnection, Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA

The observations made by the Magnetospheric Multiscale Satellite (MMS) mission, which NASA launched in 2015 to study reconnection in the magnetic field that surrounds the Earth, correspond quite well with past and present laboratory findings of the Magnetic Reconnection Experiment (MRX) at PPPL. Previous MRX research uncovered the process by which rapid reconnection occurs and identified the amount of magnetic energy that is converted to particle energy during the process, which gives rise to northern lights, solar flares and geomagnetic storms that can disrupt cell phone service, black out power grids and damage orbiting satellites.

Guidelines for MMS measurements

The previous MRX findings served as guidelines for measurements taken by the MMS mission, which seeks to understand the region in which the reconnection of field lines in plasma — the state of matter composed of free electrons and atomic nuclei, or ions — takes place. The latest PPPL experiments extend the findings to new areas of agreement. “Despite huge differences in the size of the reconnection layers in the MRX and in space, remarkably similar characteristics are observed in both,” said Masaaki Yamada, principal investigator on the MRX, and lead author of the recent paper reporting the results in the December 6 edition of Nature Communications .

The past laboratory research examined “symmetric” reconnection, in which the density of the plasmas on each side of the reconnection regions are roughly the same. The new paper looks at reconnection in the magnetopause — the outer region of the magnetosphere — and in the MRX that is “asymmetric,” meaning that the plasma on one side of the region is at least 10 times denser than on the other. The MMS mission has focused its initial research on the asymmetric aspect of reconnection, since the plasma in the solar wind — the charged particles flowing from the sun — is vastly denser than the plasma in the magnetosphere.

In the new paper, researchers examine what is called the “two-fluid” physics of reconnection that describes each behavior of ions and electrons differently during the process. Such physics dominates magnetic reconnection in both MRX and magnetospheric plasma systems, allowing for an unprecedented level of cross-examination between laboratory measurements and space observations.

Key findings

Following are key findings of the two-fluid, asymmetric research on MRX that is shown to be in striking agreement with measurements of electron and ion behavior by the space satellites and the conversion of magnetic energy to particle energy. Computer simulations aided these findings:

• Electrons. The experiments demonstrated that electron current flows perpendicular, and not parallel as once thought, to the magnetic field. This flow is key to the conversion of magnetic energy in electrons that occurs in a narrow boundary layer called the “electron diffusion region” where rapid reconnection takes place. The finding is consistent with the recent MMS space measurements and new in the laboratory for asymmetric reconnection.

• Ions. The ion current also flows perpendicular to the magnetic field as in the electron case, and likewise is key to the conversion of ion magnetic energy to particle energy. For ions, this conversion occurs in the wider “ion diffusion region” between converging plasmas and is a similarly recent finding about asymmetric reconnection in laboratory plasmas.

The MRX experiments further studied different aspects of conversion in the symmetric and asymmetric cases. In symmetric reconnection, 50 percent of magnetic energy was previously found to be converted to ions and electrons, with one-third of the conversion affecting the electrons and two-thirds accelerating the ions. The total conversion rate remains roughly the same in the asymmetric case, as does the ratio of energy conversion for ions and electrons.

PPPL researchers contributing to this study were Jongsoo Yoo, Will Fox, Jonathan Jara-Almote and Hantao Ji. Also contributing were physicists at the NASA Goddard Space Flight Center, Los Alamos National Laboratory, the Southwest Research Institute, and the universities of New Hampshire and Bergen in Bergen, Norway. Computer simulations were conducted at Los Alamos National Laboratory. Support for this work comes from DOE’s Office of Science, NASA, and the National Science Foundation.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

PPPL campus

Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

#magnetic-reconnection, #magnetospheric-multiscale-satellite-mms-mission-launched-in-2015, #physics, #pppl, #princeton-magnetic-reconnection-experiment-mrx-at-pppl

From COSMOS Magazine: “Supercomputer finds clues to violent magnetic events”

Cosmos Magazine bloc

From COSMOS Magazine

24 October 2018
Phil Dooley

An aurora over Iceland, the product of sudden magnetic reconnection. Credit Natthawat/Getty Images

Researchers are a step closer to understanding the violent magnetic events that cause the storms on the sun’s surface and fling clouds of hot gas out into space, thanks to colossal computer simulations at Princeton University in the US.

The disruptions in the magnetic field, known as magnetic reconnections, are common in the universe – the same process causes the aurora in high latitude skies – but existing models are unable to explain how they happen so quickly.

A team led by Jackson Matteucci decided to investigate by building a full three-dimensional simulation of the ejected hot gas, something that required enormous computing power. The results are published in the journal Physical Review Letters.

The researchers modelled more than 200 million particles using Titan, the biggest supercomputer [no longer true, the writer should have known that] in the US.

ORNL Cray Titan XK7 Supercomputer, once the fastest in the world.

They discovered that a three-dimensional interaction called the Biermann battery effect was at the heart of the sudden reconnection process.

Discovered in the fifties by German astrophysicist Ludwig Biermann, the Biermann battery effect shows how magnetic fields can be generated in charged gases, known as plasma.

In such plasmas, if a region develops in which there is a temperature gradient at right angles to a density gradient, a magnetic field is created that encircles it.

Astrophysicists propose that this effect might take place in interstellar plasma clouds, such as nebulae, and generate the cosmic magnetic fields that we see throughout the universe.

In contrast with the huge scale of cosmic plasma clouds, magnetic reconnection happens at a scale of microns when two magnetic fields collide, says Matteucci.

He likens the process to collisions between two sizable handfuls of rubber bands. In stable circumstances the magnetic field lines are loops, like the bands. But sometimes turbulence in the plasma pushes these band analogues together so forcefully that they sever and reconnect to different ones, thus forming loops at different orientations.

Some of the new loops are stretched taut and snap back, providing the energy that ejects material so violently, and causes magnetic storms or glowing auroras.

The Princeton simulation showed that as the fields collide there is a sudden spike in the temperature in a very localised region, which sets off the Biermann battery effect, suddenly creating a new magnetic field in the midst of the collision. It’s this newly-appearing field that severs the lines and allows them to reconfigure.

Although Matteucci’s simulations are for tiny plasma clouds generated by lasers hitting foil, he says they could help us understand large-scale processes in the atmosphere.

“If you do a back of the envelope calculation, you find it could play an important role in reconnection in the magnetosphere, where the solar wind collides with the Earth’s magnetic field,” he says.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

#biermann-battery-effect, #cosmos, #magnetic-reconnection, #ornl-cray-xk7-titan-supercomputer, #princeton-university, #solar-research

From MIT News-“Nuno Loureiro: Probing the world of plasmas”

MIT News
MIT Widget

From MIT News

October 15, 2018
David L. Chandler

A major motivation for moving to MIT from his research position, Nuno Loureiro says, was working with students. Image: Jared Charney

Physicist explores the behavior of the universe’s most abundant form of matter.

Growing up in the small city of Viseu in central Portugal, Nuno Loureiro knew he wanted to be a scientist, even in the early years of primary school when “everyone else wanted to be a policeman or a fireman,” he recalls. He can’t quite place the origin of that interest in science: He was 17 the first time he met a scientist, he says with an amused look.

By the time Loureiro finished high school, his interest in science had crystallized, and “I realized that physics was what I liked best,” he says. During his undergraduate studies at the IST Lisbon, he began to focus on fusion, which “seemed like a very appealing field,” where major developments were likely during his lifetime, he says.

Fusion, and specifically the physics of plasmas, has remained his primary research focus ever since, through graduate school, postdoc stints, and now in his research and teaching at MIT. He explains that plasma research “lives in two different worlds.” On the one hand, it involves astrophysics, dealing with the processes that happen in and around stars; on the other, it’s part of the quest to generate electricity that’s clean and virtually inexhaustible, through fusion reactors.

Plasma is a sort of fourth phase of matter, similar to a gas but with the atoms stripped apart into a kind of soup of electrons and ions. It forms about 99 percent of the visible matter in the universe, including stars and the wispy tendrils of material spread between them. Among the trickiest challenges to understanding the behavior of plasmas is their turbulence, which can dissipate away energy from a reactor, and which proceeds in very complex and hard-to-predict ways — a major stumbling block so far to practical fusion power.

While everyone is familiar with turbulence in fluids, from breaking waves to cream stirred into coffee, plasma turbulence can be quite different, Loureiro explains, because plasmas are riddled with magnetic and electric fields that push and pull them in dynamic ways. “A very noteworthy example is the solar wind,” he says, referring to the ongoing but highly variable stream of particles ejected by the sun and sweeping past Earth, sometimes producing auroras and affecting the electronics of communications satellites. Predicting the dynamics of such flows is a major goal of plasma research.

“The solar wind is the best plasma turbulence laboratory we have,” Loureiro says. “It’s increasingly well-diagnosed, because we have these satellites up there. So we can use it to benchmark our theoretical understanding.”

Loureiro began concentrating on plasma physics in graduate school at Imperial College London and continued this work as a postdoc at the Princeton Plasma Physics Laboratory and later the Culham Centre for Fusion Energy, the U.K.’s national fusion lab. Then, after a few years as a principal researcher at the University of Portugal, he joined the MIT faculty at the Plasma Science and Fusion Center in 2016 and earned tenure in 2017. A major motivation for moving to MIT from his research position, he says, was working with students. “I like to teach,” he says. Another was the “peerless intellectual caliber of the Plasma Science and Fusion Center at MIT.”

Loureiro, who holds a joint appointment in MIT’s Department of Physics, is an expert on a fundamental plasma process called magnetic reconnection. One example of this process occurs in the sun’s corona, a glowing irregular ring that surrounds the disk of the sun and becomes visible from Earth during solar eclipses. The corona is populated by vast loops of magnetic fields, which buoyantly rise from the solar interior and protrude through the solar surface. Sometimes these magnetic fields become unstable and explosively reconfigure, unleashing a burst of energy as a solar flare. “That’s magnetic reconnection in action,” he says.

Over the last couple of years at MIT, Loureiro published a series of papers with physicist Stanislav Boldyrev at the University of Wisconsin, in which they proposed a new analytical model to reconcile critical disparities between models of plasma turbulence and models of magnetic reconnection. It’s too early to say if the new model is correct, he says, but “our work prompted a reanalysis of solar wind data and also new numerical simulations. The results from these look very encouraging.”

Their new model, if proven, shows that magnetic reconnection must play a crucial role in the dynamics of plasma turbulence over a significant range of spatial scales – an insight that Loureiro and Boldyrev claim would have profound implications.

Loureiro says that a deep, detailed understanding of turbulence and reconnection in plasmas is essential for solving a variety of thorny problems in physics, including the way the sun’s corona gets heated, the properties of accretion disks around black holes, nuclear fusion, and more. And so he plugs away, to continue trying to unravel the complexities of plasma behavior. “These problems present beautiful intellectual challenges,” he muses. “That, in itself, makes the challenge worthwhile. But let’s also keep in mind that the practical implications of understanding plasma behavior are enormous.”

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

MIT Seal

The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

MIT Campus

#astrophysics, #fusion-technology, #magnetic-reconnection, #mit, #mit-plasma-science-and-fusion-center, #nuno-loureiro, #physicist-explores-the-behavior-of-the-universes-most-abundant-form-of-matter, #physics-of-plasmas, #plasma-is-a-sort-of-fourth-phase-of-matter, #the-solar-wind-is-the-best-plasma-turbulence-laboratory-we-have, #turbulence-a-major-stumbling-block-so-far-to-practical-fusion-power