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  • richardmitnick 8:33 pm on November 13, 2017 Permalink | Reply
    Tags: , Findings could help scientists understand cosmic rays solar flares and solar eruptions — emissions from the sun that can disrupt cell phone service and knock out power grids on Earth, , , , , Solar eruptions   

    From PPPL: “Plasma from lasers can shed light on cosmic rays, solar eruptions” 


    PPPL

    November 10, 2017
    Raphael Rosen

    1
    PPPL physicist Will Fox. (Photo by Elle Starkman)

    Lasers that generate plasma can provide insight into bursts of subatomic particles that occur in deep space, scientists have found. Such findings could help scientists understand cosmic rays, solar flares and solar eruptions — emissions from the sun that can disrupt cell phone service and knock out power grids on Earth.

    Physicists have long observed that particles like electrons and atomic nuclei can accelerate to extremely high speeds in space. Researchers believe that processes associated with plasma, the hot fourth state of matter in which electrons have separated from atomic nuclei, might be responsible. Some models theorize that magnetic reconnection, which takes place when the magnetic field lines in plasma snap apart and reconnect, releasing large amounts of energy, might cause the acceleration.

    Addressing this issue, a team of researchers led by Will Fox, physicist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), recently used lasers to create conditions that mimic astrophysical behavior. The laboratory technique enables the study of outer-space-like plasma in a controlled and reproducible environment. “We want to reproduce the process in miniature to conduct these tests,” said Fox, lead author of the research published in the journal Physics of Plasmas.

    The team used a simulation program called Plasma Simulation Code (PSC) that tracks plasma particles in a virtual environment, where they are acted on by simulated magnetic and electric fields. The code originated in Germany and was further developed by Fox and colleagues at the University of New Hampshire before he joined PPPL. Researchers conducted the simulations on the Titan supercomputer at the Oak Ridge Leadership Computing Facility, a DOE Office of Science User Facility, at Oak Ridge National Laboratory, through the DOE’s Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program.

    ORNL Cray Titan XK7 Supercomputer

    The simulations build on research by Fox and other scientists establishing that laser-created plasmas can facilitate the study of acceleration processes. In the new simulations, such plasmas bubble outward and crash into each other, triggering magnetic reconnection. These simulations also suggest two kinds of processes that transfer energy from the reconnection event to particles.

    During one process, known as Fermi acceleration, particles gain energy as they bounce back and forth between the outer edges of two converging plasma bubbles. In another process called X-line acceleration, the energy transfers to particles as they interact with the electric fields that arise during reconnection.

    Fox and the team now plan to conduct physical experiments that replicate conditions in the simulations using both the OMEGA laser facility at the University of Rochester’s Laboratory for Laser Energetics and the National Ignition Facility at the DOE’s Lawrence Livermore National Laboratory. “We’re trying to see if we can get particle acceleration and observe the energized particles experimentally,” Fox said.

    Collaborating with Fox on the research reported in Physics of Plasmas were physicists at PPPL, Princeton University, and the University of Michigan. Funding came from the DOE’s Office of Science (Fusion Energy Sciences and the National Nuclear Security Administration).

    See the full article here .

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    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 science.energy.gov.

     
  • richardmitnick 8:39 am on August 16, 2017 Permalink | Reply
    Tags: , , , , , , Solar eruptions, Tracking a solar eruption through the Solar System   

    From ESA: “Tracking a solar eruption through the Solar System” 

    ESA Space For Europe Banner

    European Space Agency

    15 August 2017
    Olivier Witasse
    European Space Agency
    Email: olivier.witasse@esa.int

    Markus Bauer
    ESA Science and Robotic Exploration Communication Officer
    Tel: +31 71 565 6799
    Mob: +31 61 594 3 954
    Email: Markus.Bauer@esa.int

    Ten spacecraft, from ESA’s Venus Express to NASA’s Voyager-2, felt the effect of a solar eruption as it washed through the Solar System while three other satellites watched, providing a unique perspective on this space weather event.

    NASA/Voyager 2

    Scientists working on ESA’s Mars Express were looking forward to investigating the effects of the close encounter of Comet Siding Spring on the Red Planet’s atmosphere on 19 October 2014, but instead they found what turned out to be the imprint of a solar event.

    ESA/Mars Express Orbiter

    While this made the analysis of any comet-related effects far more complex than anticipated, it triggered one of the largest collaborative efforts to trace the journey of an interplanetary ‘coronal mass ejection’ – a CME – from the Sun to the far reaches of the outer Solar System.

    Although Earth itself was not in the firing line, a number of Sun-watching satellites near Earth – ESA’s Proba-2, the ESA/NASA SOHO and NASA’s Solar Dynamics Observatory – had witnessed a powerful solar eruption a few days earlier, on 14 October.

    ESA/NASA SOHO

    NASA/SDO

    NASA’s Stereo-A not only captured images of the other side of the Sun with respect to Earth, but also collected in situ information as the CME rushed passed.

    NASA/STEREO spacecraft

    2
    In the firing line

    Thanks to the fortuitous locations of other satellites lying in the direction of the CME’s travel, unambiguous detections were made by three Mars orbiters – ESA’s Mars Express, NASA’s Maven and Mars Odyssey – and NASA’s Curiosity Rover operating on the Red Planet’s surface, ESA’s Rosetta at Comet 67P/Churyumov–Gerasimenko, and the international Cassini mission at Saturn.

    NASA/Mars MAVEN

    NASA/Mars Odyssey Spacecraft

    NASA/Mars Curiosity Rover

    ESA/Rosetta spacecraft

    NASA/ESA/ASI Cassini-Huygens Spacecraft

    Hints were even found as far out as NASA’s New Horizons, which was approaching Pluto at the time, and beyond to Voyager-2.

    NASA/New Horizons spacecraft

    However, at these large distances it is possible that evidence of this specific eruption may have merged with the background solar wind.

    “CME speeds with distance from the Sun is not well understood, in particular in the outer Solar System,” says ESA’s Olivier Witasse, who led the study.

    “Thanks to the precise timings of numerous in situ measurements, we can better understand the process, and feed our results back into models.”

    The measurements give an indication of the speed and direction of travel of the CME, which spread out over an angle of at least 116º to reach Venus Express and Stereo-A on the eastern flank, and the spacecraft at Mars and Comet 67P Churyumov–Gerasimenko on the western flank.

    From an initial maximum of about 1000 km/s estimated at the Sun, a strong drop to 647 km/s was measured by Mars Express three days later, falling further to 550 km/s at Rosetta after five days. This was followed by a more gradual decrease to 450–500 km/s at the distance of Saturn a month since the event.

    3
    Multispacecraft view

    The data also revealed the evolution of the CME’s magnetic structure, with the effects felt by spacecraft for several days, providing useful insights on space weather effects at different planetary bodies. The signatures at the various spacecraft typically included an initial shock, a strengthening of the magnetic field, and increases in the solar wind speed.

    In the case of ESA’s Venus Express, its science package was not switched on because Venus was ‘behind’ the Sun as seen from Earth, limiting communication capabilities.

    A faint indication was inferred from its star tracker being overwhelmed with radiation at the expected time of passage.

    Furthermore, several craft carrying radiation monitors – Curiosity, Mars Odyssey, Rosetta and Cassini ­­– revealed an interesting and well-known effect: a sudden decrease in galactic cosmic rays. As a CME passes by, it acts like a protective bubble, temporarily sweeping aside the cosmic rays and partially shielding the planet or spacecraft.

    4
    Cosmic ray drop

    A drop of about 20% in cosmic rays was observed at Mars – one of the deepest recorded at the Red Planet – and persisted for about 35 hours. At Rosetta a reduction of 17% was seen that lasted for 60 hours, while at Saturn the reduction was slightly lower and lasted for about four days. The increase in the duration of the cosmic ray depression corresponds to a slowing of the CME and the wider region over which it was dispersed at greater distances.

    “The comparison of the decrease in galactic cosmic ray influx at three widely separated locations due to the same CME is quite novel,” says Olivier. “While multispacecraft observations of CMEs have been done in the past, it is uncommon for the circumstances to be such to include so many spread across the inner and outer Solar System like this.

    “Finally, coming back to our original intended observation of the passage of Comet Siding Spring at Mars, the results show the importance of having a space weather context for understanding how these solar events might influence or even mask the comet’s signature in a planet’s atmosphere.”

    Interplanetary coronal mass ejection observed at Stereo-A, Mars, comet 67P/Churyumov–Gerasimenko, Saturn and New Horizons en route to Pluto. Comparison of its Forbush decreases at 1.4, 3.1 and 9.9 AU, by O. Witasse et al. is published in Journal of Geophysical Research: Space Physics, a journal of the American Geophysical Union.

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 11:19 am on August 13, 2017 Permalink | Reply
    Tags: , NASA Watches the Sun Put a Stop to Its Own Eruption, Solar eruptions   

    From Goddard: “NASA Watches the Sun Put a Stop to Its Own Eruption” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    Aug. 11, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    On Sept. 30, 2014, multiple NASA observatories watched what appeared to be the beginnings of a solar eruption. A filament — a serpentine structure consisting of dense solar material and often associated with solar eruptions — rose from the surface, gaining energy and speed as it soared. But instead of erupting from the Sun, the filament collapsed, shredded to pieces by invisible magnetic forces.

    Because scientists had so many instruments observing the event, they were able to track the entire event from beginning to end, and explain for the first time how the Sun’s magnetic landscape terminated a solar eruption. Their results are summarized in a paper published in The Astrophysical Journal on July 10, 2017.


    Watch the video to view the observations and models that enabled scientists to track the failed solar eruption from its onset up through the solar atmosphere — and ultimately understand why it faded away. Credits: NASA’s Goddard Space Flight Center/Genna Duberstein, producer.

    “Each component of our observations was very important,” said Georgios Chintzoglou, lead author of the paper and a solar physicist at Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, California, and the University Corporation for Atmospheric Research in Boulder, Colorado. “Remove one instrument, and you’re basically blind. In solar physics, you need to have good coverage observing multiple temperatures — if you have them all, you can tell a nice story.”

    The study makes use of a wealth of data captured by NASA’s Solar Dynamics Observatory, NASA’s Interface Region Imaging Spectrograph, JAXA/NASA’s Hinode, and several ground-based telescopes in support of the launch of the NASA-funded VAULT2.0 sounding rocket.

    NASA/SDO

    JAXA/HINODE spacecraft

    Together, these observatories watch the Sun in dozens of different wavelengths of light that reveal the Sun’s surface and lower atmosphere, allowing scientists to track the eruption from its onset up through the solar atmosphere — and ultimately understand why it faded away.

    The day of the failed eruption, scientists pointed the VAULT2.0 sounding rocket — a sub-orbital rocket that flies for some 20 minutes, collecting data from above Earth’s atmosphere for about five of those minutes — at an area of intense, complex magnetic activity on the Sun, called an active region. The team also collaborated with IRIS to focus its observations on the same region.

    “We were expecting an eruption; this was the most active region on the Sun that day,” said Angelos Vourlidas, an astrophysicist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, principal investigator of the VAULT2.0 project and co-author of the paper. “We saw the filament lifting with IRIS, but we didn’t see it erupt in SDO or in the coronagraphs. That’s how we knew it failed.”

    The Sun’s landscape is controlled by magnetic forces, and the scientists deduced the filament must have met some magnetic boundary that prevented the unstable structure from erupting. They used these observations as input for a model of the Sun’s magnetic environment. Much like scientists who use topographical data to study Earth, solar physicists map out the Sun’s magnetic features, or topology, to understand how these forces guide solar activity.

    Chintzoglou and his colleagues developed a model that identified locations on the Sun where the magnetic field was especially compressed, since rapid releases of energy — such as those they observed when the filament collapsed — are more likely to occur where magnetic field lines are strongly distorted.

    “We computed the Sun’s magnetic environment by tracing millions of magnetic field lines and looking at how neighboring field lines connect and diverge,” said Antonia Savcheva, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and co-author of the paper. “The amount of divergence gives us a measure of the topology.”

    Their model shows this topology shapes how solar structures evolve on the Sun’s surface. Typically, when solar structures with opposite magnetic orientations collide, they explosively release magnetic energy, heating the atmosphere with a flare and erupting into space as a coronal mass ejection — a massive cloud of solar material and magnetic fields.

    But on the day of the Sept. 2014 near-eruption, the model indicated the filament instead pushed up against a complex magnetic structure, shaped like two igloos smashed against each other. This invisible boundary, called a hyperbolic flux tube, was the result of a collision of two bipolar regions on the sun’s surface — a nexus of four alternating and opposing magnetic fields ripe for magnetic reconnection, a dynamic process that can explosively release great amounts of stored energy.

    “The hyperbolic flux tube breaks the filament’s magnetic field lines and reconnects them with those of the ambient Sun, so that the filament’s magnetic energy is stripped away,” Chintzoglou said.

    This structure eats away at the filament like a log grinder, spraying chips of solar material and preventing eruption. As the filament waned, the model demonstrates heat and energy were released into the solar atmosphere, matching the initial observations. The simulated reconnection also supports the observations of bright flaring loops where the hyperbolic flux tube and filament met — evidence for magnetic reconnection.

    While scientists have speculated such a process exists, it wasn’t until they serendipitously had multiple observations of such an event that they were able to explain how a magnetic boundary on the Sun is capable of halting an eruption, stripping a filament of energy until it’s too weak to erupt.

    “This result would have been impossible without the coordination of NASA’s solar fleet in support of our rocket launch,” Vourlidas said.

    This study indicates the Sun’s magnetic topology plays an important role in whether or not an eruption can burst from the Sun. These eruptions can create space weather effects around Earth.

    “Most research has gone into how topology helps eruptions escape,” Chintzoglou said. “But this tells us that apart from the eruption mechanism, we also need to consider what the nascent structure encounters in the beginning, and how it might be stopped.”

    See the full article here.

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    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

     
  • richardmitnick 9:51 am on April 27, 2017 Permalink | Reply
    Tags: Joint Japan Aerospace Exploration Agency NASA Hinode satellite, , Scientists Propose Mechanism to Describe Solar Eruptions of All Sizes, , Solar eruptions,   

    From Goddard: “Scientists Propose Mechanism to Describe Solar Eruptions of All Sizes” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    April 26, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    A long filament erupted on the sun on Aug. 31, 2012, shown here in imagery captured by NASA’s Solar Dynamics Observatory. Credit: NASA’s Goddard Space Flight Center/SDO
    From long, tapered jets to massive explosions of solar material and energy, eruptions on the sun come in many shapes and sizes. Since they erupt at such vastly different scales, jets and the massive clouds — called coronal mass ejections, or CMEs — were previously thought to be driven by different processes.

    Scientists from Durham University in the United Kingdom and NASA now propose that a universal mechanism can explain the whole spectrum of solar eruptions. They used 3-D computer simulations to demonstrate that a variety of eruptions can theoretically be thought of as the same kind of event, only in different sizes and manifested in different ways. Their work is summarized in a paper published in Nature on April 26, 2017.


    Follow the evolution of a jet eruption in this video, which uses a 3-D computer simulation of the breakout model to demonstrate how a filament forms, gains energy and erupts from the sun.
    Credits: NASA’s Goddard Space Flight Center/ARMS/Genna Duberstein, producer

    The study was motivated by high-resolution observations of filaments from NASA’s Solar Dynamics Observatory, or SDO, and the joint Japan Aerospace Exploration Agency/NASA Hinode satellite.

    NASA/SDO

    JAXA/HINODE spacecraft

    Filaments are dark, serpentine structures that are suspended above the sun’s surface and consist of dense, cold solar material. The onset of CME eruptions had long been known to be associated with filaments, but improved observations have recently shown that jets have similar filament-like structures before eruption too. So the scientists set out to see if they could get their computer simulations to link filaments to jet eruptions as well.

    “In CMEs, filaments are large, and when they become unstable, they erupt,” said Peter Wyper, a solar physicist at Durham University and the lead author of the study. “Recent observations have shown the same thing may be happening in smaller events such as coronal jets. Our theoretical model shows the jet can essentially be described as a mini-CME.”

    Solar scientists can use computer models like this to help round out their understanding of the observations they see through space telescopes. The models can be used to test different theories, essentially creating simulated experiments that cannot, of course, be performed on an actual star in real life.

    The scientists call their proposed mechanism for how these filaments lead to eruptions the breakout model, for the way the stressed filament pushes relentlessly at — and ultimately breaks through — its magnetic restraints into space. They previously used this model to describe CMEs; in this study, the scientists adapted the model to smaller events and were able to reproduce jets in the computer simulations that match the SDO and Hinode observations. Such simulations provide additional confirmation to support the observations that first suggested coronal jets and CMEs are caused in the same way.

    “The breakout model unifies our picture of what’s going on at the sun,” said Richard DeVore, a co-author of the study and solar physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Within a unified context, we can advance understanding of how these eruptions are started, how to predict them and how to better understand their consequences.”

    The key for understanding a solar eruption, according to Wyper, is recognizing how the filament system loses equilibrium, which triggers eruption. In the breakout model, the culprit is magnetic reconnection — a process in which magnetic field lines come together and explosively realign into a new configuration.

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

    In stable conditions, loops of magnetic field lines hold the filament down and suppress eruption. But the filament naturally wants to expand outward, which stresses its magnetic surroundings over time and eventually initiates magnetic reconnection. The process explosively releases the energy stored in the filament, which breaks out from the sun’s surface and is ejected into space.

    Exactly which kind of eruption occurs depends on the initial strength and configuration of the magnetic field lines containing the filament. In a CME, field lines form closed loops completely surrounding the filament, so a bubble-shaped cloud ultimately bursts from the sun. In jets, nearby fields lines stream freely from the surface into interplanetary space, so solar material from the filament flows out along those reconnected lines away from the sun.

    “Now we have the possibility to explain a continuum of eruptions through the same process,” Wyper said. “With this mechanism, we can understand the similarities between small jets and massive CMEs, and infer eruptions anywhere in between.”

    Confirming this theoretical mechanism will require high-resolution observations of the magnetic field and plasma flows in the solar atmosphere, especially around the sun’s poles where many jets originate — and that’s data that currently are not available. For now, scientists look to upcoming missions such as NASA’s Solar Probe Plus and the joint ESA (European Space Agency)/NASA Solar Orbiter, which will acquire novel measurements of the sun’s atmosphere and magnetic fields emanating from solar eruptions.

    NASA/SPP Solar Probe Plus

    NASA/ESA Solar Orbiter

    See the full article here.

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    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.


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  • richardmitnick 7:52 am on November 5, 2016 Permalink | Reply
    Tags: , , Solar eruptions,   

    From Caltech: “Realistic Solar Corona Loops Simulated in Lab” 

    Caltech Logo
    Caltech

    11/04/2016

    Robert Perkins
    (626) 395-1862
    rperkins@caltech.edu

    1
    Side-by-side: A real coronal loop (left) compared to one simulated in Paul Bellan’s lab (right).
    Credit: Courtesy of P. Bellan/Caltech

    Caltech applied physicists have experimentally simulated the sun’s magnetic fields to create a realistic coronal loop in a lab.

    Coronal loops are arches of plasma that erupt from the surface of the sun following along magnetic field lines. Because plasma is an ionized gas—that is, a gas of free-flowing electrons and ions—it is an excellent conductor of electricity. As such, solar corona loops are guided and shaped by the sun’s magnetic field.

    The earth’s magnetic field acts as a shield that protects humans from the strong X-rays and energized particles emitted by the eruptions, but communications satellites orbit outside this shield field and therefore remain vulnerable. In March 1989, a particularly large flare unleashed a blast of charged particles that temporarily knocked out one of the National Oceanic and Atmospheric Administration’s geostationary operational environmental satellites that monitor the earth’s weather; caused a sensor problem on the space shuttle Discovery; and tripped circuit breakers on Hydro-Québec’s power grid, which blacked out the province of Quebec in Ontario, Canada, for nine hours.

    “This potential for causing havoc—which only increases the more humanity relies on satellites for communications, weather forecasting, and keeping track of resources—makes understanding how these solar events work critically important,” says Paul Bellan, professor of applied physics in the Division of Engineering and Applied Science.

    Although simulated coronal loops have been created in labs before, this latest attempt incorporated a magnetic strapping field that binds the loop to the sun’s surface. Think of a strapping field like the metal hoops on the outside of a wooden barrel. While the slats of the barrel are continually under pressure pushing outward, the metal hoops sit perpendicularly to the slats and hold the barrel together.

    The strength of this strapping field diminishes with distance from the sun. This means that when close to the solar surface, the loops are clamped down tightly by the strapping field but then can break loose and blast away if they rise to a certain altitude where the strapping field is weaker. These eruptions are known as solar flares and coronal mass ejections (CMEs).

    CMEs are rope-like discharges of hot plasma that accelerate away from the sun’s surface at speeds of more than a million miles per hour. These eruptions are capable of releasing energy equivalent to 1 billion megatons of TNT, making them potentially the most powerful explosions in the solar system. (CMEs are not to be confused with solar flares, which often occur as part of the same event. Solar flares are bursts of light and energy, while CMEs are blasts of particles embedded in a magnetic field.)

    The simulated loops and strapping fields provide new insight into how energy is stored in the solar corona and then released suddenly. Bellan worked with Caltech graduate student Bao Ha (MS ’10, PhD ’16) to create the strapping field and coronal loop. The results of their experiments were published in the journal Geophysical Research Letters on September 17, 2016.

    Bellan and his colleagues have been working on laboratory-scale simulations of solar corona phenomena for two decades. In the lab, the team generates ropes of plasma in a 1.5-meter-long vacuum chamber.

    “Studying coronal mass ejections is challenging, since humans do not know how and when the sun will erupt. But laboratory experiments permit the control of eruption parameters and enable the systematic explorations of eruption dynamics,” says Ha, lead author of the GRL paper. “While experiments with the same eruption parameters are easily reproducible, the loop dynamics vary depending on the configuration of the strapping magnetic field.”

    Simulating a strapping field with strength that fades over the relatively short length of the vacuum chamber proved difficult, Bellan says. In order to make it work, Ha and Bellan had to engineer electromagnetic coils that produce the strapping field inside the chamber itself.

    After more than three years of design, fabrication, and testing, Bellan and Ha were able to create a strapping field that peaks in strength about 10 centimeters away from where the plasma loop forms, then dies off a short distance farther down the vacuum chamber.

    The arrangement allows Bellan and Ha to watch the plasma loop slowly grow in size, then reach a critical point and fire off to the far end of the chamber.

    Next, Bellan plans to measure the magnetic field inside the erupting loop and also study the waves that are emitted when plasmas break apart.

    Their paper, titled Laboratory demonstration of slow rise to fast acceleration of arched magnetic flux ropes, is available online at http://onlinelibrary.wiley.com/doi/10.1002/2016GL069744/full. The research was supported by the National Science Foundation, the Air Force Office of Scientific Research, and the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences.

    See the full article here .

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    Caltech campus
    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

     
  • richardmitnick 9:11 am on August 1, 2016 Permalink | Reply
    Tags: , , , Solar eruptions   

    From ESA: “Solar eruption larger than Earth” 

    ESA Space For Europe Banner

    European Space Agency

    01/08/2016
    No writer credit

    1
    SOHO (ESA & NASA)

    ESA/SOHO
    ESA/SOHO

    A gigantic ribbon of hot gas bursts upwards from the Sun, guided by a giant loop of invisible magnetism. This remarkable image was captured on 27 July 1999 by SOHO, the Solar and Heliospheric Observatory. Earth is superimposed for comparison and shows that from top to bottom the loop of gas, or prominence, extends about 35 times the diameter of our planet into space.

    A prominence is an extension of gas that arches up from the surface of the Sun. Prominences are sculpted by magnetic fields that are generated inside the Sun, and then burst through the surface, propelling themselves into the solar atmosphere.

    The Sun is predominantly made of plasma – an electrified gas of electrons and ions. Being electrically charged, the ions respond to magnetic fields. So when the magnetic loops reach up into the solar atmosphere, huge streams of plasma are attracted to fill them, creating the prominences that can last for weeks or months.

    Spectacular prominences like this one are not particularly common, a few being detected each year. When they start to collapse, mostly the gas ‘drains’ down the magnetic field lines back into the Sun. Occasionally, however, they become unstable and release their energy into space. These eruptive prominences fling out a huge quantity of plasma that solar physicists call a coronal mass ejection. Solar flares are also associated with coronal mass ejections.

    If this plasma hits Earth it can disrupt satellites, power grids and communications. It also causes the aurora to shine in the polar skies.

    Taken by SOHO’s ultraviolet telescope, this image shows ionised helium at a temperature of about 70 000ºC.

    A version of the image without the Earth for comparison can be found here.

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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