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  • richardmitnick 9:04 am on September 23, 2020 Permalink | Reply
    Tags: "Nanojets; nanoflares; & magnetic reconnection: the quest to solve the coronal heating problem", , For the first time scientists have observed nanojets- bright thin lights traveling perpendicular to the magnetic field lines of the Sun that are the telltale signature of nanoflares., If the solar surface is 5500℃ how can the solar atmosphere (the corona) be between 1 million and 10 million degrees C?, JAXA Hinode observatory of Japan Europe and NASA., NASA developed the Interface Region Imaging Spectrograph (IRIS) spacecraft., NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker, ,   

    From NASA Spaceflight: “Nanojets, nanoflares, & magnetic reconnection: the quest to solve the coronal heating problem” 

    NASA Spaceflight

    From NASA Spaceflight

    September 22, 2020
    Chris Gebhardt

    1

    It’s one of the most baffling problems in astrophysics. If the solar surface is 5,500℃, how can the solar atmosphere (the corona) be between 1 million and 10 million degrees C?

    For the first time, scientists have observed nanojets, bright thin lights traveling perpendicular to the magnetic field lines of the Sun that are the telltale signature of nanoflares: localized, rapid heating events of the corona.

    The issue of coronal heating was first identified by astrophysicists in the 1940s. Since then, numerous hypotheses have been put forth to explain how the Sun’s atmosphere is many times hotter than its surface.

    One such hypothesis put forward by Peter Gold and developed by Eugene Parker (for whom the Parker Solar Probe is named) is nanoflares, periodic small-scale heating events of the corona.

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

    But a fundamental problem with this hypothesis — and others — was not being able to directly observe the complex physical processes at work in the corona.

    Despite lacking a way to see the event, scientific models showed that a faint, hot emission from a nanoflare would be detectable and measurable.

    To help study the corona in more detail, NASA developed the Interface Region Imaging Spectrograph (IRIS) spacecraft to determine how the corona is heated and directly measure and observe the processes taking place at the transition point between the solar surface and corona.

    NASA IRIS spacecraft.

    Built by Lockheed Martin, the 183 kg solar observatory was launched on 28 June 2013 (UTC) onboard a now-Northrop Grumman Pegasus-XL rocket off the coast of California.


    ScienceCasts: The Mystery of Coronal Heating.

    Just over nine months later, it observed the event that led to yesterday’s nanojet discovery and coronal heating announcement published in the journal Nature Astronomy.

    On 3 April 2014, IRIS observed a coronal rain event — when streams of cool plasma fall from the corona back toward the Sun’s surface.

    During a period of 15 minutes, the portion of the corona under observation transitioned from a region filled with cool plasma to a place millions of degrees in temperature.

    In examining the data obtained by IRIS, a team of international researchers led by Dr. Patrick Antolin of Northumbria University, observed bright jets near the end of the coronal rain event.

    These flashes were streams of heated plasma traveling so fast they appeared as bright thin lines moving sideways through the magnetic field lines.

    Those flashes are nanojets — the predicted proof of nanoflares.

    “From coordinated multi-band high-resolution observations we discovered evidence of very fast and explosive nanojets, the tell-tale signature of reconnection-based nanoflares resulting in coronal heating,” said Dr. Antolin.

    The normally smooth magnetic field lines of the Sun can become tangled and woven together… and then violently snap back into their previously smooth selves. That snap-back process is called reconnection, and it converts the energy stored in the solar magnetic field into motion in the plasma environment of the corona.

    The localized plasma motion is quickly stopped by the surrounding plasma’s viscosity and turbulence in such a way that the motion (energy) is converted into heat — raising the localized coronal temperature.


    NASA Satellites Spot Nanojets On Sun.
    A faint, hot emission (the observable nanojet) from this small heating event escapes and travels perpendicular to the magnetic field lines.

    In and of itself, a small event like that would not explain the coronal heating problem. But one magnetic reconnection event triggers another which triggers another… leading to a cascading series of reconnections and nanoflares and detectable nanojets.

    This kind of cascading event is exactly what was observed by IRIS in the form of a “nanojet storm” during the same 15 minute period in April 2014 when the under-observation portion of the corona suddenly heated from a cool plasma region to a millions of degrees environment.

    With these observations in hand, there was a strong link between nanojets, nanoflares, and magnetic reconnection as a coronal heating mechanism. But more evidence was needed.

    The international team of researchers then coordinated with NASA’s Solar Dynamics Observatory and the Hinode observatory of Japan, Europe, and NASA to obtain a full view of the Sun to confirm their nanojets detection and assess nanojet effects on the corona.

    NASA/SDO.

    JAXA/NASA HINODE spacecraft.

    Over the next several years, the team utilized advanced, state-of-the-art simulations to recreate what they saw during the coronal heating event of April 2014.

    Using all of the collected data, the models showed nanojets are a signature of magnetic reconnection and nanoflares and that the events do contribute to coronal heating.

    “Using state-of-the-art numerical simulations, we have demonstrated that the nanojet is a consequence of the slingshot effect from the magnetically tensed, curved magnetic field lines reconnecting at small angles,” noted Dr. Antolin. “Nanojets are therefore the key signature to look for reconnection-based coronal heating in action.”

    3

    In announcing the nanojet discovery and evidence for coronal heating via magnetic reconnection and nanoflares, Dr. Antolin and his team were quick to note that additional observations and studies are needed to establish how frequent nanoflare activity is throughout the corona and exactly how much of the total energy for heating the corona those events provide.

    They also caution, as many astrophysicists do, that a singular explanation for coronal heating is unlikely, and that the large up swing in temperatures seen in the solar atmosphere is likely the result of several complex and overlapping processes.

    “The solar corona is very diverse, so it is likely there are many heating mechanisms,” said Dr. Antolin. “In active regions, the most energy demanding regions, [magnetic reconnection] may dominate because it releases a lot of energy.”

    IRIS is not the only mission currently seeking to unlock the mysteries of the corona.

    NASA’s Parker Solar Probe, launched in August 2018, is the first spacecraft to directly fly into and study the corona from the inside.

    Conversely, the European Space Agency’s Solar Orbiter, launched in February 2020, will aid in the investigation of coronal heating by seeking to understand how and where the Sun’s magnetic field forms in the corona.

    ESA/NASA Solar Orbiter depiction.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    NASA Spaceflight , now in its eighth year of operations, is already the leading online news resource for everyone interested in space flight specific news, supplying our readership with the latest news, around the clock, with editors covering all the leading space faring nations.

    Breaking more exclusive space flight related news stories than any other site in its field, NASASpaceFlight.com is dedicated to expanding the public’s awareness and respect for the space flight industry, which in turn is reflected in the many thousands of space industry visitors to the site, ranging from NASA to Lockheed Martin, Boeing, United Space Alliance and commercial space flight arena.

    With a monthly readership of 500,000 visitors and growing, the site’s expansion has already seen articles being referenced and linked by major news networks such as MSNBC, CBS, The New York Times, Popular Science, but to name a few.

     
  • richardmitnick 5:20 pm on July 29, 2019 Permalink | Reply
    Tags: “We’re not re-creating the sun because that’s impossible” says plasma physicist Ethan Peterson of the University of Wisconsin–Madison. “But we’re re-creating some of the fundamental phys, , NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker, Parker spiral named after solar physicist Eugene Parker who predicted the existence of the solar wind in 1958., , , , , The magnet in the center of the ball mimics the sun’s magnetic field and carefully applied electric currents send the plasma spinning and a wind streaming., The sun spews a constant stream of charged particles-called the solar wind out into space - though scientists aren’t sure exactly how., The team used a 3-meter-wide aluminum vacuum chamber called the Big Red Ball heated to 100000° Celsius at the Wisconsin Plasma Physics Laboratory.,   

    From University of Wisconsin Madison via Science News: “In a first, physicists re-created the sun’s spiraling solar wind in a lab” 

    U Wisconsin

    From University of Wisconsin Madison

    via

    Science News

    July 29, 2019
    Lisa Grossman

    Some of the sun’s fundamental physics have been re-created with plasma inside a vacuum chamber.

    1
    SUN IN A BALL This view shows the inside of the Big Red Ball, a 3-meter-wide aluminum sphere at the University of Wisconsin–Madison that can mimic properties of the sun. Carefully applied magnets and electric currents make the plasma spin and send out streams of charged particles, like the solar wind. Univ. of Wisconsin-Madison

    Physicists have created mini gusts of solar wind in the lab, with hopes that the charged particle streams can help to resolve some mysteries about our nearest star [Nature Physics].

    “We’re not re-creating the sun, because that’s impossible,” says plasma physicist Ethan Peterson of the University of Wisconsin–Madison, who reports the new work July 29 in Nature Physics. “But we’re re-creating some of the fundamental physics that happens near the sun.”

    The sun spews a constant stream of charged particles, called the solar wind, out into space — though scientists aren’t sure exactly how (SN Online: 8/18/17). As the sun rotates, its magnetic field twists the wind into a helical shape called the Parker spiral, named after solar physicist Eugene Parker, who predicted the existence of the solar wind in 1958.

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

    NASA last year launched its Parker Solar Probe to directly investigate the source of the solar wind (SN: 7/21/18, p. 12). But Peterson and colleagues found a way to mimic the Parker spiral much closer to home.

    The team used a 3-meter-wide aluminum vacuum chamber called the Big Red Ball at the Wisconsin Plasma Physics Laboratory to confine a ball of plasma heated to 100,000° Celsius. A magnet in the center of the ball mimics the sun’s magnetic field, and carefully applied electric currents send the plasma spinning and a wind streaming.

    There are some unavoidable differences between the Big Red Ball and the sun, including size, gravity and temperature. Even so, the wind organized itself into a clear Parker spiral, as expected. The wind also occasionally ejected little blobs of plasma, each about 10 centimeters across. The sun ejects similar blobs, called plasmoids, but no one is sure why. The Big Red Ball could help provide an answer, Peterson says.


    BALLERINA SKIRT The Parker spiral, which has also been described as a “ballerina skirt,” is the shape that the solar wind takes on as the sun rotates, twisting the wind into a helix as seen in a NASA simulation. Scientists mimicked this spiral in plasma in the lab. This video shows a smaller Parker spiral appearing in a ball of hot, spinning plasma inside a vacuum chamber. The bright spiraling structures follow the plasma’s magnetic field.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    In achievement and prestige, the University of Wisconsin–Madison has long been recognized as one of America’s great universities. A public, land-grant institution, UW–Madison offers a complete spectrum of liberal arts studies, professional programs and student activities. Spanning 936 acres along the southern shore of Lake Mendota, the campus is located in the city of Madison.

     
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