The hottest catalog of the year: Comprehensive list of slow-building solar flares

Solar flares occur when magnetic energy builds up in the Sun's atmosphere and is released as electromagnetic radiation. Lasting anywhere from a few minutes to a few hours, flares usually reach temperatures around 10 million degrees Kelvin. Because of their intense electromagnetic energy, solar flares can cause disruptions in radio communications, Earth-orbiting satellites and even result in blackouts.

Although flares have been classified based on the amount of energy they emit at their peak, there has not been significant study into differentiating flares based on the speed of energy build-up since slow-building flares were first discovered in the 1980s.

In a new paper in Solar Physics, a team, led by UC San Diego astrophysics graduate student Aravind Bharathi Valluvan, has shown that there is a significant amount of slower-type flares worthy of further investigation.

The width-to-decay ratio of a flare is the time it takes to reach maximum intensity to the time it takes to dissipate its energy.

Most commonly, flares spend more time dissipating than rising.

In a 5-minute flare, it may take 1 minute to rise and 4 minutes to dissipate for a ratio of 1:4. In slow-building flares, that ratio may be 1:1, with 2.5 minutes to rise and 2.5 minutes to dissipate.

Valluvan was a student at the Indian Institute of Technology Bombay (IITB) when this work was conducted.

Exploiting the increased capabilities of the Chandrayaan-2 solar orbiter, IITB researchers used the first three years of observed data to catalog nearly 1400 slow-rising flares -- a dramatic increase over the roughly 100 that had been previously observed over the past four decades.

It was thought that solar flares were like the snap of a whip -- quickly injecting energy before slowly dissipating.

Now seeing slow-building flares in such high quantities may change that thinking.

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Tree rings offer insight into devastating radiation storms

A University of Queensland study has shed new light on a mysterious, unpredictable and potentially devastating kind of astrophysical event.

A team led by Dr Benjamin Pope from UQ's School of Mathematics and Physics applied cutting edge statistics to data from millennia-old trees, to find out more about radiation 'storms'.

"These huge bursts of cosmic radiation, known as Miyake Events, have occurred approximately once every thousand years but what causes them is unclear," Dr Pope said.

"The leading theory is that they are huge solar flares.

"We need to know more, because if one of these happened today, it would destroy technology including satellites, internet cables, long-distance power lines and transformers.

"The effect on global infrastructure would be unimaginable."

Enter the humble tree ring.

First author UQ undergraduate maths student Qingyuan Zhang developed software to analyse every available piece of data on tree rings.

"Because you can count a tree's rings to identify its age, you can also observe historical cosmic events going back thousands of years," Mr Zhang said.

"When radiation strikes the atmosphere it produces radioactive carbon-14, which filters through the air, oceans, plants, and animals, and produces an annual record of radiation in tree rings.

"We modelled the global carbon cycle to reconstruct the process over a 10,000-year period, to gain insight into the scale and nature of the Miyake Events."

The common theory until now has been that Miyake Events are giant solar flares.

"But our results challenge this," Mr Zhang said.

"We've shown they're not correlated with sunspot activity, and some actually last one or two years.

"Rather than a single instantaneous explosion or flare, what we may be looking at is a kind of astrophysical 'storm' or outburst."

Dr Pope said the fact scientists don't know exactly what Miyake Events are, or how to predict their occurrence is very disturbing.

"Based on available data, there's roughly a one per cent chance of seeing another one within the next decade.

"But we don't know how to predict it or what harms it may cause.

"These odds are quite alarming, and lay the foundation for further research."

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Particle accelerator region revealed inside a solar flare

Solar flares are among the most violent explosions in our solar system, but despite their immense energy -- equivalent to a hundred billion atomic bombs detonating at once -- physicists still haven't been able to answer exactly how these sudden eruptions on the Sun are able to launch particles to Earth, nearly 93 million miles away, in under an hour.

Now, in a study published June 8 in Nature, researchers at New Jersey Institute of Technology (NJIT) have pinpointed the precise location where solar flare charged particles are accelerated to near-light speed.

The new findings, made possible through observations of an X-class solar flare in 2017 by NJIT's Expanded Owens Valley Solar Array (EOVSA) radio telescope, have revealed a highly efficient particle accelerator located at the tip of the brightest point of the eruption in the Sun's outer atmosphere, called the flare's "cusp region," where the explosion's ambient plasma is converted to high-energy electrons.

Researchers say the discovery of the region, measured at almost twice the volume of Earth, could open new doors for investigating fundamental processes of particle acceleration ubiquitous in the universe.

"The findings in this study help explain the long-standing mystery of how solar flares can produce so much energy in mere seconds," said Gregory Fleishman, corresponding author of the paper and distinguished research professor of physics at NJIT's Center for Solar-Terrestrial Research. "The flare unleashes its power in a much vaster region of the Sun than expected by the classic model of solar flares. Although others have postulated this must happen, this is the first time the specific size, shape, and location of this key region has been identified, and the efficiency of the energy conversion to particle acceleration inside the flare has been measured."

The discovery follows separate studies from 2020 published in Science and Nature Astronomy, where EOVSA's detailed snapshots of the flare and changes in the Sun's magnetic field -- taken at hundreds of radio frequencies at once -- initially gave the NJIT team a lead on the location.

"Our recent studies suggested the flare cusp could be the location where such high-energy electrons are produced, but we weren't certain," explained Bin Chen, NJIT associate professor and a co-author of the paper. "We had originally uncovered a magnetic bottle-like structure at the site that contained an overwhelmingly large number of electrons compared to anywhere else in the flare, but now with the new measurements of this study, we can more confidently say this is the flare's particle accelerator.''

Using the unique microwave imaging capabilities of EOVSA, the team was able to measure the energy spectrum of electrons at hundreds of locations of an X-class solar flare triggered by a reconfiguration of magnetic field lines along the Sun's surface on September 10, 2017.

"EOVSA's spectral imaging gave us a comprehensive map of the flare's thermal plasma as it evolved second-by-second. But to our surprise, what we found was a mysterious hole in the thermal plasma map that began developing at the flare's cusp," said Gelu Nita, NJIT research professor and co-author of the paper. "More than that, as thermal particles in the region disappeared, the hole was then densely filled with non-thermal, high-energy particles."

The team's analysis brought to light an incredibly efficient energy conversion process within the solar flare's particle accelerator, where intense energy from the Sun's magnetic fields is rapidly released and transferred to kinetic energy inside the region.

"We wondered how efficient this energy conversion process would be … how many particles in this area would be accelerated beyond the explosion's thermal energy?" added Sijie Yu, study co-author and NJIT assistant research professor. "Using extreme ultraviolet data of the Sun, we confirmed that virtually no particles remained inside the region at thermal energies below a few million Kelvin, consistent with the EOVSA measurement that the particles had all been accelerated to non-thermal energies greater than 20 keV, or nearly 100 million Kelvin."

The team now says these latest findings could help scientists study fundamental questions in particle physics not possible on Earth, as well as offer fresh insights into how such high-energy particles from the Sun may impact Earth during future space weather events.

"An important aspect of this study is that it directs the attention of theorists to the precise location where most of the energy release and particle acceleration occurs, and provides quantitative measurements to guide numerical models," says Dale Gary, NJIT distinguished professor and director of EOVSA. "However, to extend our measurements to much broader flare regions and weaker but more frequent flare events, we are developing a next-generation, solar-dedicated radio array called the Frequency Agile Solar Radiotelescope, which will be at least 10 times larger and orders of magnitude more powerful."

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A roadmap for deepening understanding of a puzzling universal process

A puzzling process called magnetic reconnection triggers explosive phenomena throughout the universe, creating solar flares and space storms that can take down mobile phone service and electrical power grids. Now scientists at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have detailed a roadmap for untangling a key aspect of this puzzle that could deepen insight into the workings of the cosmos.

Reconnection converts the magnetic field energy to particle eruptions in astrophysical plasmas by snapping apart and explosively reconnecting the magnetic field lines -- a process that occurs within what are called dissipation regions that are often enormously smaller than the regions they impact.

Stressed magnetic field

"Plasma doesn't like reconnection," said Hantao Ji, a PPPL physicist and Princeton University professor who is first author of a paper that details the roadmap in Nature Reviews Physics. "However, reconnection does happen when the magnetic field is sufficiently stressed," he said.

"Dissipation scales are tiny whereas astrophysical scales are very large and can extend for millions of miles. Finding a way to bridge these scales through a multiscale mechanism is a key to solving the reconnection puzzle."

The roadmap outlines the role of developing technologies with multiscale capabilities such as the Facility for Laboratory Reconnection Experiment (FLARE), a recently installed collaborative facility that is being upgraded and will probe facets of magnetic reconnection never before accessible to laboratory experiments. Complementing these experiments will be simulations on coming exascale supercomputers that will be 10 times faster than current computers. "The hope is for FLARE and exascale computing to go hand-in-hand," Ji said.

The working theory the PPPL roadmap proposes is that multiple plasmoids, or magnetic islands, that arise from reconnection along lengthy plasma current sheets could bridge the vast range of scales. Such plasmoids would correspond more closely to the affected reconnection region, with multiscale laboratory experiments planned to provide the first tests of this theory and to evaluate competing hypotheses.

"Exascale will allow us to do more credible simulations based on high-fidelity FLARE experiments," said PPPL physicist Jongsoo Yoo, a coauthor of the paper. The increased size and power of the new machine -- its diameter will be twice that of the sports-utility-vehicle-sized Magnetic Reconnection Experiment (MRX), PPPL's long-standing laboratory experiment -- and will enable scientists to replicate reconnection in nature more faithfully.

"FLARE can access wider astrophysical regimes than MRX with multiple reconnection points and measure the field geometry during reconnection," said William Daughton, a computational scientist at Los Alamos National Laboratory and a coauthor of the paper. "Understanding this physics is important for predicting how reconnection proceeds in solar flares," he said.

Key challenge

A key challenge to the coming experiments will be innovating new high-resolution diagnostic systems free from restrictive assumptions. Once developed these systems will enable FLARE to build upon satellite sightings such as those produced by the Magnetospheric Multiscale mission, a fleet of four spacecraft launched in 2015 to study reconnection in the magnetosphere, the magnetic field that surrounds the Earth.

"Progress in understanding multiscale physics critically depends on innovation and efficient implementation of such diagnostics systems in the coming decade," the paper said. The new findings will address open questions that include:

• How exactly does reconnection start?
• How are explosive plasma particles heated and accelerated?
• What role does reconnection play in related processes such as turbulence and space shocks?

Overall, "The paper lays out plans to provide the entire space physics and astrophysics communities with methods to solve the multiscale problem," Yoo said. Such a solution would mark a major step toward a more complete understanding of magnetic reconnection in large systems throughout the universe.

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Scientists explain mysterious finger-like features in solar flares

In January 1999, scientists observed mysterious motions within a solar flare.

Unlike typical flares that showed bright energy erupting outwards from the Sun, this solar flare also displayed a downward flow of motion, as if material was falling back towards the Sun. Described as "downward-moving dark voids," astronomers wondered what exactly they were seeing.

Now, in a study published today in Nature Astronomy, astronomers at the Center for Astrophysics | Harvard & Smithsonian (CfA) offer a new explanation for the poorly understood downflows, now referred to as supra-arcade downflows (SADs) by the scientific community.

"We wanted to know how these structures occur," says lead author and CfA astronomer Chengcai Shen, who describes the structures as "dark finger-like features." "What's driving them and are they truly tied to magnetic reconnection?"

Scientists have assumed that SADs are tied to magnetic reconnection since their discovery in the 90s. The process occurs when magnetic fields break, releasing fast moving and extremely energetic radiation, and then reform.

"On the Sun, what happens is you have a lot of magnetic fields that are pointing in all different directions. Eventually the magnetic fields are pushed together to the point where they reconfigure and release a lot of energy in the form of a solar flare," says study co-author and CfA astronomer Kathy Reeves.

Reeves adds, "It's like stretching out a rubber band and snipping it in the middle. It's stressed and stretched thin, so it's going to snap back."

Scientists assumed the dark downflows were signs of the broken magnetic fields "snapping back" to the Sun after a solar flare eruption.

But there was a catch.

Most of the downflows observed by scientists are "puzzlingly slow," says co-author Bin Chen, an astronomer at the New Jersey Institute of Technology.

Shen explains, "This is not predicted by classic reconnection models, which show the downflows should be much quicker. It's a conflict that requires some other explanation."

To find out what was happening, the team analyzed downflow images captured by the Atmospheric Imaging Assembly (AIA) onboard NASA's Solar Dynamics Observatory. Designed and built partially at the CfA and led by the Lockheed Martin Solar Astrophysics Laboratory, the AIA takes images of the Sun every twelve seconds in seven different wavelengths of light to measure variations in the Sun's atmosphere.

They then made 3D simulations of solar flares and compared them to the observations.

The results show that most SADs are not generated by magnetic reconnection after all. Instead, they form on their own in the turbulent environment and are the result of two fluids with different densities interacting.

Reeves says scientists are essentially seeing the same thing that happens when water and oil are mixed together: the two different fluid densities are unstable and ultimately separate.

"Those dark, finger-like voids are actually an absence of plasma. The density is much lower there than the surrounding plasma," Reeves says.

The team plans to continue studying SADs and other solar phenomenon using 3D simulations to better understand magnetic reconnection. By understanding the processes that drive solar flares and eruptions from the Sun, they may ultimately help develop tools to forecast space weather and mitigate its impacts.

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Lightning impacts edge of space in ways not previously observed

Solar flares jetting out from the sun and thunderstorms generated on Earth impact the planet's ionosphere in different ways, which have implications for the ability to conduct long range communications.

A team of researchers working with data collected by the Incoherent Scatter Radar (ISR) at the Arecibo Observatory, satellites, and lightning detectors in Puerto Rico have for the first time examined the simultaneous impacts of thunderstorms and solar flares on the ionospheric D-region (often referred to as the edge of space).

In the first of its kind analysis, the team determined that solar flares and lightning from thunderstorms trigger unique changes to that edge of space, which is used for long-range communications such the GPS found in vehicles and airplanes.

The work, led by New Mexico Tech assistant professor of physics Caitano L. da Silva was published recently in the journal Scientific Reports, a journal of the Nature Publishing Group.

"These are really exciting results," says da Silva. "One of the key things we showed in the paper is that lightning- and solar flare-driven signatures are completely different. The first tends to create electron density depletions, while the second enhancements (or ionization)."

While the AO radar used in the study is no longer available because of the collapse of AO's telescope in December of 2020, scientists believe that the data they collected and other AO historical data will be instrumental in advancing this work.

"This study helps emphasize that, in order to fully understand the coupling of atmospheric regions, energy input from below (from thunderstorms) into the lower ionosphere needs to be properly accounted for," da Silva says. "The wealth of data collected at AO over the years will be a transformative tool to quantify the effects of lightning in the lower ionosphere."

Better understanding the impact on the Earth's ionosphere will help improve communications.

da Silva worked with a team of researchers at the Arecibo Observatory (AO) in Puerto Rico, a National Science Foundation facility managed by the University of Central Florida under a cooperative agreement. The co-authors are AO Senior Scientist Pedrina Terra, Assistant Director of Science Operations Christiano G. M. Brum and Sophia D. Salazar a student at NMT who spent her 2019 summer at the AO as part of the NSF- supported Research Undergraduate Experience. Salazar completed the initial analysis of the data as part of her internship with the senior scientists' supervision.

"The Arecibo Observatory REU is hands down one of the best experiences I've had so far," says the 21-year-old. "The support and encouragement provided by the AO staff and REU students made the research experience everything that it was. There were many opportunities to network with scientists at AO from all over the world, many of which I would likely never have met without the AO REU."

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The upside of volatile space weather

 

Giant solar flare illustration.

Although violent and unpredictable, stellar flares emitted by a planet's host star do not necessarily prevent life from forming, according to a new Northwestern University study.

Emitted by stars, stellar flares are sudden flashes of magnetic imagery. On Earth, the sun's flares sometimes damage satellites and disrupt radio communications. Elsewhere in the universe, robust stellar flares also have the ability to deplete and destroy atmospheric gases, such as ozone. Without the ozone, harmful levels of ultraviolet (UV) radiation can penetrate a planet's atmosphere, thereby diminishing its chances of harboring surface life.

By combining 3D atmospheric chemistry and climate modeling with observed flare data from distant stars, a Northwestern-led team discovered that stellar flares could play an important role in the long-term evolution of a planet's atmosphere and habitability.

"We compared the atmospheric chemistry of planets experiencing frequent flares with planets experiencing no flares. The long-term atmospheric chemistry is very different," said Northwestern's Howard Chen, the study's first author. "Continuous flares actually drive a planet's atmospheric composition into a new chemical equilibrium."

"We've found that stellar flares might not preclude the existence of life," added Daniel Horton, the study's senior author. "In some cases, flaring doesn't erode all of the atmospheric ozone. Surface life might still have a fighting chance."

The study will be published on Dec. 21 in the journal Nature Astronomy. It is a joint effort among researchers at Northwestern, University of Colorado at Boulder, University of Chicago, Massachusetts Institute of Technology and NASA Nexus for Exoplanet System Science (NExSS).

Horton is an assistant professor of Earth and planetary sciences in Northwestern's Weinberg College of Arts and Sciences. Chen is a Ph.D. candidate in Horton's Climate Change Research Group and a NASA future investigator.

Importance of flares

All stars -- including our very own sun -- flare, or randomly release stored energy. Fortunately for Earthlings, the sun's flares typically have a minimal impact on the planet.

"Our sun is more of a gentle giant," said Allison Youngblood, an astronomer at the University of Colorado and co-author of the study. "It's older and not as active as younger and smaller stars. Earth also has a strong magnetic field, which deflects the sun's damaging winds."

Unfortunately, most potentially habitable exoplanets aren't as lucky. For planets to potentially harbor life, they must be close enough to a star that their water won't freeze -- but not so close that water vaporizes.

"We studied planets orbiting within the habitable zones of M and K dwarf stars -- the most common stars in the universe," Horton said. "Habitable zones around these stars are narrower because the stars are smaller and less powerful than stars like our sun. On the flip side, M and K dwarf stars are thought to have more frequent flaring activity than our sun, and their tidally locked planets are unlikely to have magnetic fields helping deflect their stellar winds."

Chen and Horton previously conducted a study of M dwarf stellar systems' long term climate averages. Flares, however, occur on an hours- or days-long timescales. Although these brief timescales can be difficult to simulate, incorporating the effects of flares is important to forming a more complete picture of exoplanet atmospheres. The researchers accomplished this by incorporating flare data from NASA's Transiting Exoplanet Satellite Survey, launched in 2018, into their model simulations.

Using flares to detect life

If there is life on these M and K dwarf exoplanets, previous work hypothesizes that stellar flares might make it easier to detect. For example, stellar flares can increase the abundance of life-indicating gasses (such as nitrogen dioxide, nitrous oxide and nitric acid) from imperceptible to detectable levels.

"Space weather events are typically viewed as a detriment to habitability," Chen said. "But our study quantitatively shows that some space weather can actually help us detect signatures of important gases that might signify biological processes."

This study involved researchers from a wide range of backgrounds and expertise, including climate scientists, exoplanet scientists, astronomers, theorists and observers.

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New research explores how super flares affect planets' habitability

 

Exoplanet illustration

Ultraviolet light from giant stellar flares can destroy a planet's habitability. New research from the University of North Carolina at Chapel Hill will help astrobiologists understand how much radiation planets experience during super flares and whether life could exist on worlds beyond our solar system.

Super flares are bursts of energy that are 10 to 1,000 times larger than the biggest flares from the Earth's sun. These flares can bathe a planet in an amount of ultraviolet light huge enough to doom the chances of life surviving there.

Researchers from UNC-Chapel Hill have for the first time measured the temperature of a large sample of super flares from stars, and the flares' likely ultraviolet emissions. Their findings, published Oct. 5 ahead of print in Astrophysical Journal, will allow researchers to put limits on the habitability of planets that are targets of upcoming planet-finding missions.

"We found planets orbiting young stars may experience life-prohibiting levels of UV radiation, although some micro-organisms might survive," said lead study author Ward S. Howard, a doctoral student in the Department of Physics and Astronomy at UNC-Chapel Hill.

Howard and colleagues at UNC-Chapel Hill used the UNC-Chapel Hill Evryscope telescope array and NASA's Transiting Exoplanet Survey Satellite (TESS) to simultaneously observe the largest sample of super flares.

The team's research expands upon previous work that has largely focused on flare temperatures and radiation from only a handful of super flares from a few stars. In expanding the research, the team discovered a statistical relationship between the size of a super flare and its temperature. The temperature predicts the amount of radiation that potentially precludes on-surface life.

Super flares typically emit most of their UV radiation during a rapid peak lasting only five to 15 minutes. The simultaneous Evryscope and TESS observations were obtained at two-minute intervals, ensuring multiple measurements were taken during the peak of each super flare.

This is the first time the temperatures of such a large sample of super flares has ever been studied. The frequency of observations allowed the team to discover the amount of time super flares can cook orbiting planets with intense UV radiation.

The flares observed have already informed the TESS Extended Mission to discover thousands of exoplanets in orbit around the brightest dwarf stars in the sky. TESS is now targeting high priority flare stars from the UNC-Chapel Hill sample for more frequent observations.

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Rare 'superflares' could one day threaten Earth

Giant solar flare illustration.

Astronomers probing the edges of the Milky Way have in recent years observed some of the most brilliant pyrotechnic displays in the galaxy: superflares.

These events occur when stars, for reasons that scientists still don't understand, eject huge bursts of energy that can be seen from hundreds of light years away. Until recently, researchers assumed that such explosions occurred mostly on stars that, unlike Earth's, were young and active.

Now, new research shows with more confidence than ever before that superflares can occur on older, quieter stars like our own -- albeit more rarely, or about once every few thousand years.

The results should be a wake-up call for life on our planet, said Yuta Notsu, the lead author of the study and a visiting researcher at CU Boulder.

If a superflare erupted from the sun, he said, Earth would likely sit in the path of a wave of high-energy radiation. Such a blast could disrupt electronics across the globe, causing widespread black outs and shorting out communication satellites in orbit.

Notsu presented his research at a press briefing at the 234th meeting of the American Astronomical Society in St. Louis.

"Our study shows that superflares are rare events," said Notsu, a researcher in CU Boulder's Laboratory for Atmospheric and Space Physics. "But there is some possibility that we could experience such an event in the next 100 years or so."

Scientists first discovered this phenomenon from an unlikely source: the Kepler Space Telescope. The NASA spacecraft, launched in 2009, seeks out planets circling stars far from Earth. But it also found something odd about those stars themselves. In rare events, the light from distant stars seemed to get suddenly, and momentarily, brighter.

Researchers dubbed those humungous bursts of energy "superflares."

Notsu explained that normal-sized flares are common on the sun. But what the Kepler data was showing seemed to be much bigger, on the order of hundreds to thousands of times more powerful than the largest flare ever recorded with modern instruments on Earth.

And that raised an obvious question: Could a superflare also occur on our own sun?

"When our sun was young, it was very active because it rotated very fast and probably generated more powerful flares," said Notsu, also of the National Solar Observatory in Boulder. "But we didn't know if such large flares occur on the modern sun with very low frequency."

To find out, Notsu and an international team of researchers turned to data from the European Space Agency's Gaia spacecraft and from the Apache Point Observatory in New Mexico. Over a series of studies, the group used those instruments to narrow down a list of superflares that had come from 43 stars that resembled our sun. The researchers then subjected those rare events to a rigorous statistical analysis.

The bottom line: age matters. Based on the team's calculations, younger stars tend to produce the most superflares. But older stars like our sun, now a respectable 4.6 billion years old, aren't off the hook.

"Young stars have superflares once every week or so," Notsu said. "For the sun, it's once every few thousand years on average."

The group published its latest results in May in The Astrophysical Journal.

Notsu can't be sure when the next big solar light show is due to hit Earth. But he said that it's a matter of when, not if. Still, that could give humans time to prepare, protecting electronics on the ground and in orbit from radiation in space.

Read more at Science Daily

Flares in the universe can now be studied on Earth

Solar flares are caused by magnetic reconnection in space and can interfere with our communications satellites, affecting power grids, air traffic and telephony. Now, researchers at Chalmers University of Technology, Sweden, have found a new way to imitate and study these spectacular space plasma phenomena in a laboratory environment.

Solar flares, cosmic radiation, and the northern lights are well known phenomena. But exactly how their enormous energy arises is not as well understood.

Now, physicists at Chalmers University of Technology, Sweden, have discovered a new way to study these spectacular space plasma phenomena in a laboratory environment. The results have been published in the journal Nature Communications.

"Scientists have been trying to bring these space phenomena down to earth for a decade. With our new method we can enter a new era, and investigate what was previously impossible to study. It will tell us more about how these events occur," says Longqing Yi, researcher at the Department of Physics at Chalmers.

The research concerns so-called 'magnetic reconnection' -- the process which gives rise to these phenomena. Magnetic reconnection causes sudden conversion of energy stored in the magnetic field into heat and kinetic energy. This happens when two plasmas with anti-parallel magnetic fields are pushed together, and the magnetic field lines converge and reconnect. This interaction leads to violently accelerated plasma particles that can sometimes be seen with the naked eye -- for example, during the northern lights.

Magnetic reconnection in space can also influence us on earth. The creation of solar flares can interfere with communications satellites, and thus affect power grids, air traffic and telephony.

In order to imitate and study these spectacular space plasma phenomena in the laboratory, you need a high-power laser, to create magnetic fields around a million times stronger than those found on the surface of the sun. In the new scientific article, Longqing Yi, along with Professor Tünde Fülöp from the Department of Physics, proposed an experiment in which magnetic reconnection can be studied in a new, more precise way. Through the use of grazing incidence of ultra-short laser pulses, the effect can be achieved without overheating the plasma. The process can thus be studied very cleanly, without the laser directly affecting the internal energy of the plasma.

The proposed experiment would therefore allow us to seek answers to some of the most fundamental questions in astrophysics.

"We hope that this can inspire many research groups to use our results. This is a great opportunity to look for knowledge that could be useful in a number of areas. For example, we need to better understand solar flares, which can interfere with important communication systems. We also need to be able to control the instabilities caused by magnetic reconnection in fusion devices," says Tünde Fülöp.

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