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  • richardmitnick 1:03 am on February 8, 2020 Permalink | Reply
    Tags: , , , “Introduction” to the Special Issue by Marcia Neugebauer, , , Dust-free zone, Link to Special ApJS Issue on Parker Solar Probe, , , Plasma structures, Small energetic-particle events, , Switchbacks   

    From AAS NOVA: “Early Results from Parker Solar Probe” 


    From AAS NOVA

    7 February 2020
    Susanna Kohler

    Artist’s illustration of the Parker Solar Probe. A special ApJS issue features around 50 articles detailing early results from this mission. [NASA/Johns Hopkins APL/Steve Gribben]

    What might we learn about the Sun if we could fly a spacecraft close enough to dip down and skim through its atmosphere? Thanks to the Parker Solar Probe, we don’t have to speculate!

    The Parker Solar Probe (PSP) is a telescope designed to orbit the Sun at least 24 times, dipping closer and closer to our star’s surface over its mission lifetime.

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

    Its first few orbits have already been completed at a distance of about 35.7 solar radii from the Sun’s center. Just this past month, PSP used the gravitational pull of Venus to drop its orbit to 27.8 solar radii — and by 2024, after several such maneuvers, PSP will be flying just 8.86 solar radii (that’s less than 4 million miles) from the Sun’s surface, soaring through the Sun’s tenuous outer atmosphere.

    This innovative spacecraft will bring us our closest look yet at the magnetic structure and heating of this outer atmosphere — the Sun’s corona — and give us the chance to better explore the solar wind, the stream of energetic particles that flows off of the Sun and pervades our solar system.

    Though PSP’s orbit still has a lot further to drop, it’s already flying closer to the Sun than any other spacecraft ever has! This means we’ve already been able to do some remarkable science in the year and a half since its mission began. A new special issue of the Astrophysical Journal Supplement Series now presents roughly 50 studies detailing the findings from PSP’s first two orbits around the Sun.

    A few broad categories of topics explored among these articles are:

    Illustration of magnetic switchbacks in the solar wind, first discovered by Parker Solar Probe. Click to view an animation. [NASA’s Goddard Space Flight Center/Conceptual Image Lab/Adriana Manrique Gutierrez]


    On large scales, the solar wind looks like a smooth flow of particles streaming radially outward from the Sun. But on scales close to the Sun’s surface, this flow is much more complex. PSP has measured a phenomenon termed “switchbacks” — rapid reversals in the direction of the magnetic field that governs the solar wind flow. Several articles detail what PSP has revealed about this phenomenon.

    Plasma physics

    The high time and frequency resolutions of PSP’s instruments allow the probe to capture unprecedented observations of different plasma phenomena in the ionized gas close in around the Sun. PSP’s first two orbits have produced data on various wave modes, electron holes, magnetic reconnection, radio bursts, microinstabilities, plasma turbulence, and more. Several articles in this issue are devoted to analysis of these detections.

    Small energetic-particle events

    Some solar activity can rapidly accelerate particles to enormous speeds. Since such energetic-particle events can pose a serious hazard to spacecraft and astronauts, we want to better understand what triggers them and how the particles are accelerated. PSP detected a large number of small energetic-particle events associated with various phenomena — and several articles in this issue detail what we’ve learned from these observations.

    A huge variety of plasma structures — like this erupting filament — can be witnessed on the Sun. [NASA’s Goddard SFC]

    Plasma structures

    A huge variety of plasma structures — like this erupting filament — can be witnessed on the Sun. [NASA’s Goddard SFC]
    When plasma is ejected from the Sun, it erupts into space in a variety of structures. PSP carries a camera system that has imaged the complex features of smaller plasma structures; in this special issue, these observations are analyzed and even combined with data from other Sun-watching spacecraft to build three-dimensional views of the structures. From this, we can better understand how magnetic fields govern the geometry and motions of the ionized gas emitted from the Sun.

    Dust-free zone

    Though dust pervades our solar system, theory predicts that close to the Sun, the high temperatures should prevent dust from existing. Several articles describe PSP’s observations that suggest thinning dust levels; data from PSP’s future travels even closer to the Sun will hopefully confirm the presence of a dust-free zone and determine where, exactly, it lies.

    We’re likely at a solar minimum right now in between two activity cycles, as shown here in the predictions made from sunspot observations over the last several cycles. The Sun should become progressively more active over the course of PSP’s mission lifetime. [David Hathaway, NASA, Marshall Space Flight Center]

    These observations are just the start of what we can hope to learn from the Parker Solar Probe. We should expect to see many updates to our understanding of the corona and the solar wind as PSP explores regions closer to the Sun, as solar activity increases (we’re currently at a solar cycle minimum), and as in-flight calibrations of the PSP instruments continue. Stay tuned!


    Special ApJS Issue on Parker Solar Probe

    “Introduction,” Marcia Neugebauer 2020 ApJS 246 19.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition


    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

  • richardmitnick 1:59 pm on December 4, 2019 Permalink | Reply
    Tags: Among the findings are new understandings of how the Sun's constant outflow of solar wind behaves., , , , , First NASA Parker Solar Probe Results Reveal Surprising Details About Our Sun, , , Switchbacks   

    From NASA Parker Solar Probe: “First NASA Parker Solar Probe Results Reveal Surprising Details About Our Sun” Updated with the four Nature Papers 

    NASA image

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

    From NASA Parker Solar Probe

    Dec. 4, 2019

    Grey Hautaluoma
    Headquarters, Washington

    Karen Fox
    Headquarters, Washington

    The WISPR image on NASA’s Parker Solar Probe captured imagery of the constant outflow of material from the Sun during its close approach to the Sun in April 2019. Credits: NASA/NRL/APL

    The Sun is revealing itself in dramatic detail and shedding light on how other stars may form and behave throughout the universe – all thanks to NASA’s Parker Solar Probe. The spacecraft is enduring scorching temperatures to gather data, which are being shared for the first time in four new papers that illuminate previously unknown and only-theorized characteristics of our volatile celestial neighbor.

    The information Parker has uncovered about how the Sun constantly ejects material and energy will help scientists rewrite the models they use to understand and predict the space weather around our planet, and understand the process by which stars are created and evolve. This information will be vital to protecting astronauts and technology in space – an important part of NASA’s Artemis program, which will send the first woman and the next man to the Moon by 2024 and, eventually, on to Mars.

    The four papers, now available online from the journal Nature, describe Parker’s unprecedented near-Sun observations through two record-breaking close flybys.


    They reveal new insights into the processes that drive the solar wind – the constant outflow of hot, ionized gas that streams outward from the Sun and fills up the solar system – and how the solar wind couples with solar rotation. Through these flybys, the mission also has examined the dust of the coronal environment, and spotted particle acceleration events so small that they are undetectable from Earth, which is nearly 93 million miles from the Sun.

    During its initial flybys, Parker studied the Sun from a distance of about 15 million miles. That is already closer to the Sun than Mercury, but the spacecraft will get even closer in the future, as it travels at more than 213,000 mph, faster than any previous spacecraft.

    “This first data from Parker reveals our star, the Sun, in new and surprising ways,” said Thomas Zurbuchen, associate administrator for science at NASA Headquarters in Washington. “Observing the Sun up close rather than from a much greater distance is giving us an unprecedented view into important solar phenomena and how they affect us on Earth, and gives us new insights relevant to the understanding of active stars across galaxies. It’s just the beginning of an incredibly exciting time for heliophysics with Parker at the vanguard of new discoveries.”

    Among the findings are new understandings of how the Sun’s constant outflow of solar wind behaves. Seen near Earth, the solar wind plasma appears to be a relatively uniform flow – one that can interact with our planet’s natural magnetic field and cause space weather effects that interfere with technology. Instead of that flow, near the Sun, Parker’s observations reveal a dynamic and highly structured system, similar to that of an estuary that serves as a transition zone as a river flows into the ocean. For the first time, scientists are able to study the solar wind from its source, the Sun’s corona, similar to how one might observe the stream that serves as the source of a river. This provides a much different perspective as compared to studying the solar wind were its flow impacts Earth.

    NASA’s Parker Solar Probe observed a slow solar wind flowing out from the small coronal hole – the long, thin black spot seen on the left side of the Sun in this image captured by NASA’s Solar Dynamics Observatory – on October 27, 2018. While scientists have long known that fast solar wind streams flow from coronal holes near the poles, they have not yet conclusively identified the source of the Sun’s slow solar wind. Credits: NASA/SDO



    One type of event in particular caught the attention of the science teams – flips in the direction of the magnetic field, which flows out from the Sun, embedded in the solar wind and detected by the FIELDS instrument. These reversals – dubbed “switchbacks” – appear to be a very common phenomenon in the solar wind flow inside the orbit of Mercury, and last anywhere from a few seconds to several minutes as they flow over the spacecraft. Yet they seem not to be present any farther from the Sun, making them undetectable without flying directly through that solar wind the way Parker has.

    During a switchback, the magnetic field whips back on itself until it is pointed almost directly back at the Sun. These switchbacks, along with other observations of the solar wind, may provide early clues about what mechanisms heat and accelerate the solar wind. Not only does such information help change our understanding of what causes the solar wind and space weather affecting Earth, it also helps us understand a fundamental process of how stars work and how they release magnetic energy into their environment.

    Rotating Wind

    In a separate publication, based on measurements by the Solar Wind Electrons Alphas and Protons (SWEAP) instrument, researchers found surprising clues as to how the Sun’s rotation affects the outflow of the solar wind. Near Earth, the solar wind flows past our planet as if it travels initially in almost straight lines – or “radially,” like spokes on a bicycle wheel – out from the Sun in all directions. But the Sun rotates as it releases the solar wind, and before it breaks free, the solar wind is expected to get a push in sync with the Sun’s rotation.

    As Parker ventured to a distance of around 20 million miles from the Sun, researchers obtained their first observations of this effect. Here, the extent of this sideways motion was much stronger than predicted, but it also transitioned more quickly than predicted to a straight, strictly outward flow, which helps mask the effects at a larger distance. This enormous extended atmosphere of the Sun will naturally affect the star’s rotation. Understanding this transition point in the solar wind is key to helping us understand how the Sun’s rotation slows down over time, with implications for the lifecycles of our star, its potentially violent past, as well as other stars and the formation of protoplanetary disks, dense disks of gas and dust encircling young stars.

    Dust in the Wind

    Parker also observed the first direct evidence of dust starting to thin out around 7 million miles from the Sun – an effect that has been theorized for nearly a century, but has been impossible to measure until now. These observations were made using Parker’s Wide-field Imager for Solar Probe (WISPR) instrument, at a distance of about 4 million miles from the Sun. Scientists have long suspected that close to the Sun, this dust would be heated to high temperatures, turning it into a gas and creating a dust-free region around the star. At the observed rate of thinning, scientists expect to see a truly dust-free zone beginning at a distance of about 2-3 million miles from the Sun, which the spacecraft could observe as early as September 2020, during its sixth flyby. That dust-free zone would signal a place where the material of the dust has been evaporated by the Sun’s heat, to become part of the solar wind flying past Earth.

    Energetic Particles

    Finally, Parker’s Integrated Science Investigation of the Sun (ISʘIS) energetic particle instruments have measured several never-before-seen events so small that all traces of them are lost before they reach Earth. These instruments have also measured a rare type of particle burst with a particularly high ratio of heavier elements – suggesting that both types of events may be more common than scientists previously thought. Solar energetic particle events are important, as they can arise suddenly and lead to space weather conditions near Earth that can be potentially harmful to astronauts. Unraveling the sources, acceleration and transport of solar energetic particles will help us better protect humans in space in the future.

    “The Sun is the only star we can examine this closely,” said Nicola Fox, director of the Heliophysics Division at NASA Headquarters. “Getting data at the source already is revolutionizing our understanding of our own star and stars across the universe. Our little spacecraft is soldiering through brutal conditions to send home startling and exciting revelations.”

    Data from Parker Solar Probe’s first two solar encounters are available online at:


    For more information about Parker, visit:


    Imagery from the mission is available at:


    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Parker Solar Probe is part of NASA’s Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living with a Star program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, designed, built and operates the spacecraft.

    For more information about Parker, visit:


    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

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