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  • richardmitnick 1:27 pm on June 1, 2018 Permalink | Reply
    Tags: , , , , How solar prominences vibrate, , Solar research   

    From IAC: “How solar prominences vibrate” 


    Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    IAC

    From Instituto de Astrofísica de Canarias – IAC

    1

    Image of the sun taken by the GONG telescopes network in a halpha filter. The bumps are seen as dark filaments on the solar disk. The arrow indicates a bump ranging. In the diagram the horizontal velocity of the prominence shown. In the initial phase reaches 60 km / s. The periodic motion persists for several hours. Credit: Manuel Luna (IAC).

    An international team led by researchers at the Institute of Astrophysics of the Canary Islands (IAC) and the University of La Laguna (ULL) has cataloged about 200 oscillations of solar flares during the first half of 2014. Its development has been made possible by the network GONG telescopes, of which one is located at the Observatorio del Teide.

    When we look at the sun’s surface solar prominences are seen as dark filaments that populate the disk or plasma incandenscente languages ​​that rise above this. Solar prominences are very dense plasma structures levitated in the solar atmosphere. It is thought that the magnetic field of this star is that holds you from falling on the surface under its own weight. These magnetic structures can accumulate a large amount of energy, when released it produces eruptions throwing material to interplanetary protrusions.

    Manuel Luna, researcher at the IAC and ULL, leads the team that has cataloged about 200 oscillations of solar flares detected in the first half of 2014. This analysis, published today in The Astrophysical Journal Supplement Series, has served to verify that almost half of these events has been of great amplitude. That is, oscillation speeds between 10 km / s (360.00 km / h) and 100 km / s. It has also been found that these high-amplitude events are more common than previously thought.

    The project is part of an international collaboration that began in 2015 through the International Space Science Institute (ISSI) and NASA project to study this type of oscillations.

    With this collection, we have found a variety of events and it has been determined that, in many cases, the oscillations are produced by flares nearby. That is, by the sudden release of energy in the solar atmosphere.

    With the collected data was performed a statistical study of the properties of the oscillations. These movements consist of a cyclic movement of the projections between two positions. In it it has been seen that the oscillations (vibrations) have a period of about one hour. These periods are typical of the protuberances and reveal its fundamental properties of magnetic structure and the distribution of its mass. Furthermore, the oscillations show a large buffer, or what is the same vibration is considerably reduced after a few oscillation cycles. It is unknown why most of the protuberances oscillate with a period of an hour or why his movement is damped so quickly, which will be further investigated.

    The data suggest that “the direction of movement of the oscillations forms an angle of about 27 degrees with the main axis of prominence,” Luna said. He adds: “This address matches the previous estimates of the orientation of the magnetic field.” Furthermore, using seismic techniques, researchers have been able to deduce details about the geometry and magnetic field strength that supports the protrusions.

    This study opens a new window to the investigation of the structure of solar flares and mechanisms that eventually destabilize producing eruption. In the future, the authors intend to extend this analysis to a whole solar cycle to understand the evolution of these structures over the 11-year duration. To achieve this will have to apply artificial intelligence techniques and processing large amounts of data.

    Catalog oscillations observed with GONG solar flares .

    Article: Moon, M. et al. GONG catalog Solar Solar Oscillations of filament near maximum The Astrophysical Journal Supplement.

    The six sites comprising the GONG Network are:

    The Big Bear Solar Observatory in California, USA.

    NJIT Big Bear Solar Observatory, located on the north side of Big Bear Lake in the San Bernardino Mountains of southwestern San Bernardino County, California, approximately 120 kilometers east of downtown Los Angeles


    NJIT Big Bear Solar Observatory Interior


    NJIT Big Bear Solar Observatory New Solar Telescope

    The High Altitude Observatory at Mauna Loa in Hawaii, USA.

    3

    The Learmonth Solar Observatory in Western Australia.

    Learmonth Solar Observatory Learmonth AU

    The Udaipur Solar Observatory in India, in Udaipur, Rajasthan in India on an island in the Fateh Sagar Lake.

    4

    The Observatorio del Teide in the Canary Islands.

    The Cerro Tololo Interamerican Observatory in Chile.

    4
    GONG telescope CTIO, about 500 km north of Santiago, Chile, about 70 km east of La Serena, at an altitude of 2200

    See the full article here.


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).
    The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

    Roque de los Muchachos Observatory is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, at an altitude of 2,396 m (7,861 ft)

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teaching and outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.


    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC

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  • richardmitnick 3:17 pm on May 30, 2018 Permalink | Reply
    Tags: , , , , , Parker Solar Probe's Faraday cup, Solar research   

    From Harvard-Smithsonian Center for Astrophysics and U Michigan : “Key Parker Solar Probe Sensor Bests Sun Simulator—Last Launch Hurdle” 

    U Michigan bloc

    University of Michigan

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    April 30, 2018
    Megan Watzke
    Harvard-Smithsonian Center for Astrophysics
    +1 617-496-7998
    mwatzke@cfa.harvard.edu

    Peter Edmonds
    Harvard-Smithsonian Center for Astrophysics
    +1 617-571-7279
    pedmonds@cfa.harvard.edu

    1
    Researchers use a quartet of IMAX projectors to create the light and heat the Parker Solar Probe cup will experience during its trips through the sun’s atmosphere. The cup sits inside a vacuum chambers set up in a lab at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. Image credit: Levi Hutmacher, Michigan Engineering

    2
    Artist’s concept of the Parker Solar Probe spacecraft approaching the sun. In order to unlock the mysteries of the corona, but also to protect a society that is increasingly dependent on technology from the threats of space weather, we will send Parker Solar Probe to touch the sun. Image credit: NASA

    3
    Justin Kasper, (left), a University of Michigan associate professor of climate and space sciences engineering, awaits test results with Anthony Case, an astrophysicist at the Harvard Smithsonian Institute for Astrophysics. Image creidt: Levi Hutmacher, Michigan Engineering

    You don’t get to swim in the sun’s atmosphere unless you can prove you belong there. And the Parker Solar Probe’s Faraday cup, a key sensor aboard the $1.5 billion NASA mission launching this summer, earned its stripes last week by enduring testing in a homemade contraption designed to simulate the sun.

    The cup will scoop up and examine the solar wind as the probe passes closer to the sun than any previous manmade object. Justin Kasper, University of Michigan associate professor of climate and space sciences and engineering, is principal investigator for Parker’s Solar Wind Electrons Alphas and Protons (SWEAP) investigation.

    In order to confirm the cup will survive the extreme heat and light of the sun’s corona, researchers previously tortured a model of the Faraday cup at temperatures exceeding 3,000 degrees Fahrenheit, courtesy of the Oak Ridge National Laboratory’s Plasma Arc Lamp. The cup, built from refractory metals and sapphire crystal insulators, exceeded expectations.

    But the final test took place last week, in a homemade contraption Kasper and his research team call the Solar Environment Simulator. While being blasted with roughly 10 kilowatts of light on its surface—enough to heat a sheet of metal to 1,800 degrees Fahrenheit in seconds—the Faraday cup model ran through its paces, successfully scanning a simulated stream of solar wind.

    “Watching the instrument track the signal from the ion beam as if it was plasma flowing from the sun was a thrilling preview of what we will see with Parker Solar Probe,” Kasper said.

    Roilings in the sun’s atmosphere can violently fling clouds of plasma into space, known as coronal mass ejections, sometimes directly at Earth. Without precautionary measures, such clouds can set up geomagnetic oscillations around Earth that can trip up satellite electronics, interfere with GPS and radio communications and—at their worst—can create surges of current through power grids that can overload and disrupt the system for extended periods of time, up to months.

    By understanding what makes up the solar corona and what drives the constant outpouring of solar material from the sun, scientists on Earth will be better equipped to interpret the solar activity we see from afar and create a better early-warning system. That’s where Parker Solar Probe, slated for launch on July 31, 2018, comes in, with its complement of experiments that includes the Faraday cup.

    To test the cup model, researchers had to create something new. Their simulator sits in a first-floor lab at the Smithsonian Astrophysical Observatory in Cambridge, Mass., and embodies the adage that necessity is the mother of invention.

    It has the look of a makeshift operating room, with a metal frame holding up thick blue tarps around three sides creating a 16×8 workspace.

    Inside the area, recreating the sun’s heat and light fell to a quartet of modified older model IMAX projectors that Kasper’s team purchased on eBay for a few thousand dollars apiece. These are not the digital machines you find in today’s Cineplexes, but an earlier generation that utilized bulbs.

    “It turns out a movie theater bulb on an IMAX projector runs at about the same 5,700 degrees Kelvin—the same effective temperature as the surface of the sun,” Kasper said. “And it gives off nearly the same spectrum of light as the surface.”

    Space offers essentially no atmosphere, meaning a proper testing environment for the Faraday cup would have as little air as possible. So researchers placed the cup in a metal vacuum chamber for testing.

    Resembling an iron lung, the seven-foot-long silver chamber has a hatch at one end that swings outward and has a small round window in it. The night before testing, the team began pumping the atmosphere out of the vacuum chamber.

    By the time the simulation cranked up for testing, the chamber registered roughly one-billionth of the Earth’s atmosphere.

    All four of the IMAX projectors sit atop wheeled tables, and to set up for the test, researchers rolled them into place, with their beams pointed through the vacuum tube window directly at the Faraday cup.

    The final element of the simulator is its ability to generate the kinds of particles the Faraday cup will need to sense and evaluate. To do that, the team attached an ion gun to the vacuum tube hatch, with the “barrel” of the device reaching inside and pointed at the cup.

    “The ion gun takes a pellet of metal and heats it up,” said Anthony Case, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. “When it gets hot, ions start boiling off this piece of metal. Then you hook it up to a battery, accelerating the ions out of the gun. And we can direct them right toward the Faraday cup’s aperture where they’ll be measured.”

    In this final test, the Faraday cup took the heat and delivered—putting Parker Solar Probe on track for its summer launch.

    Kelly Korreck, a U-M alumna and astrophysicist at the institute, serves as head of science operations on Parker’s SWEAP investigation as well as SWEAP activities for the Smithsonian.

    “As for the test today, it confirmed what I had suspected—when you take an amazing team of scientists and engineers, give them a complex, difficult, interesting project and the motivation of exploring a region of the universe humankind has never been to, before remarkable things happen,” she said.

    See the full CfA article here .
    See the full U Michigan article here .


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


    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

    U MIchigan Campus

    The University of Michigan (U-M, UM, UMich, or U of M), frequently referred to simply as Michigan, is a public research university located in Ann Arbor, Michigan, United States. Originally, founded in 1817 in Detroit as the Catholepistemiad, or University of Michigania, 20 years before the Michigan Territory officially became a state, the University of Michigan is the state’s oldest university. The university moved to Ann Arbor in 1837 onto 40 acres (16 ha) of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet (781 acres or 3.16 km²), and has two satellite campuses located in Flint and Dearborn. The University was one of the founding members of the Association of American Universities.

    Considered one of the foremost research universities in the United States,[7] the university has very high research activity and its comprehensive graduate program offers doctoral degrees in the humanities, social sciences, and STEM fields (Science, Technology, Engineering and Mathematics) as well as professional degrees in business, medicine, law, pharmacy, nursing, social work and dentistry. Michigan’s body of living alumni (as of 2012) comprises more than 500,000. Besides academic life, Michigan’s athletic teams compete in Division I of the NCAA and are collectively known as the Wolverines. They are members of the Big Ten Conference.

     
  • richardmitnick 3:39 pm on February 6, 2018 Permalink | Reply
    Tags: , , , , HINODE Captures Record Breaking Solar Magnetic Field, , , Solar research   

    From NAOJ: “HINODE Captures Record Breaking Solar Magnetic Field” 

    NAOJ

    NAOJ

    JAXA/NASA HINODE spacecraft

    February 6, 2018

    1
    Snapshot of a sunspot observed by the Hinode spacecraft. (top) Visible light continuum image. (bottom) Magnetic field strength map. The color shows the field strength, from weak (cool colors) to strong (warm colors). Red indicates a location with a strength of more than 6,000 gauss (600 mT).

    Astronomers at the National Astronomical Observatory of Japan (NAOJ) using the HINODE spacecraft observed the strongest magnetic field ever directly measured on the surface of the Sun. Analyzing data for 5 days around the appearance of this record breaking magnetic field, the astronomers determined that it was generated as a result of gas outflow from one sunspot pushing against another sunspot.

    These results were published as Okamoto and Sakurai, Super-strong Magnetic Field in Sunspots, in The Astrophysical Journal Letters, 852 (2018).

    From Hinode

    Institute of Space and Astronautical Science / Japan Aerospace Exploration Agency (ISAS/JAXA)

    Astronomers at the National Astronomical Observatory of Japan (NAOJ) using the HINODE spacecraft observed the strongest magnetic field ever directly measured on the surface of the Sun. Analyzing data for 5 days around the appearance of this record breaking magnetic field, the astronomers determined that it was generated as a result of gas outflow from one sunspot pushing against another sunspot.

    Magnetism plays a critical role in various solar phenomena such as flares, mass ejections, flux ropes, and coronal heating. Sunspots are areas of concentrated magnetic fields. A sunspot usually consists of a circular dark core (the umbra) with a vertical magnetic field and radially-elongated fine threads (the penumbra) with a horizontal field. The penumbra harbors an outward flow of gas along the horizontal threads. The darkness of the umbrae is generally correlated with the magnetic field strength. Hence, the strongest magnetic field in each sunspot is located in the umbra in most cases.

    Joten Okamoto (NAOJ Fellow) and Takashi Sakurai (Professor Emeritus of NAOJ) were analyzing data of February 4, 2014 taken by the Solar Optical Telescope onboard HINODE, when they noticed the signature of strongly magnetized iron atoms in a sunspot (Figure 1). Surprisingly the data indicated a magnetic field strength of 6,250 gauss (*1). This is more than double the 3,000 gauss field found around most sunspots. Previously, magnetic fields this strong on the Sun had only been inferred indirectly. More surprisingly, the strongest field was not in the dark part of the umbra, as would be expected, but was actually located at a bright region between two umbrae.

    3
    Figure 1. (left) Snapshot of the sunspot with the strongest magnetic field. (middle) Spectrum taken along the white line in the left panel. “1” indicates the location of the strongest magnetic field. “2” indicates the location of the umbra. (right) Simplified diagram of the splitting of the iron absorption line. A large distance in the splitting means a strong magnetic field. ( ©NAOJ/JAXA)

    HINODE continuously tracked the same sunspot with high spatial resolution for several days. This is impossible for ground-based telescopes because the Earth’s rotation causes the Sun to set and night to fall on the observatories. These continuous data showed that the strong field was always located at the boundary between the bright region and the umbra, and that the horizontal gas flows along the direction of the magnetic fields over the bright region turned down into the Sun when they reached the strong-field area (Figure 2). This indicates that the bright region with the strong field is a penumbra belonging to the southern umbra (S-pole). The horizontal gas flows from the southern umbra compressed the fields near the other umbra (N-pole) and enhanced the field strength to more than 6,000 gauss.

    4
    Figure 2. Schematic illustration of the formation mechanism of the strong field. The horizontal flows from the right (S-pole umbra) compress the magnetic field near the left umbra (N-pole) and the magnetic field is enhanced. (©NAOJ)

    Okamoto explains, “HINODE’s continuous high-resolution data allowed us to analyze the sunspots in detail to investigate the distribution and time evolution of the strong magnetic field and also the surrounding environment. Finally, the longtime mystery of the formation mechanism of a stronger field outside an umbra than in the umbra, has been solved.” These results were published as Joten Okamoto and Takashi Sakurai, “Super-strong Magnetic Field in Sunspots,” in The Astrophysical Journal Letters, 852 (2018).

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

    In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

    NAOJ Subaru Telescope

    NAOJ Subaru Telescope interior
    Subaru

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array
    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    Okayama Astrophysical Observatory

    The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

    In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

     
  • richardmitnick 1:11 pm on November 30, 2017 Permalink | Reply
    Tags: AGU - From the Prow, , , , , , Solar research   

    From AGU: “22 Years of Solar and Heliospheric Observatory” 

    AGU bloc

    American Geophysical Union

    1
    From the Prow

    30 November 2017
    Bernhard Fleck (ESA SOHO Project Scientist, NASA/GSFC)
    Joseph Gurman (NASA SOHO Project Scientist, NASA/GSFC)
    David Sibeck (Past President, AGU Space Physics and Aeronomy Section, NASA/GSFC)

    ESA/NASA SOHO

    1
    The Solar and Heliospheric Observatory (SOHO) studies the internal structure of the Sun, its outer atmosphere and solar winds, and the stream of ionized gas that is constantly blowing outward through the Solar System.

    The 2nd of December 2017 marks the 22nd launch anniversary of the European Space Agency (ESA) – NASA Solar and Heliospheric Observatory (SOHO). SOHO is the longest-lived heliophysics mission still operating and has provided a nearly continuous record of solar and heliospheric phenomena over a full 22-year magnetic cycle (two 11-year sunspot cycles).

    SOHO’s findings have been documented in over 5000 papers in the peer reviewed literature, authored by more than 4,000 scientists worldwide.

    SOHO provided the first ever images of structures and flows below the Sun’s surface and of activity on the far side of the Sun. SOHO discovered sunquakes and eliminated uncertainties in the internal structure of the Sun as a possible explanation for the “neutrino problem” which concerned the large discrepancy between the high flux of solar neutrinos – particles which are now believed to possess mass and travel at almost the speed of light – predicted from the Sun’s luminosity and the much lower flux that is observed.

    The ultraviolet imagers and spectrometers on SOHO have revealed an extremely dynamic solar atmosphere where plasma flows play an important role and discovered dynamic solar phenomena such as coronal waves.

    SOHO measured the acceleration profiles of both the slow and fast solar wind and identified the source regions of the fast solar wind.

    SOHO revolutionized our understanding of solar-terrestrial relations and dramatically boosted space weather forecasting capabilities by providing, in a near-continuous stream, a comprehensive suite of images covering the dynamic atmosphere and extended corona.

    SOHO has measured and characterized over 28,000 coronal mass ejections (CMEs). CMEs are the most energetic eruptions on the Sun and the major driver of space weather. They are responsible for all of the largest solar energetic particle events in the heliosphere and are the primary cause of major geomagnetic storms. SOHO’s visible-light CME measurements are considered a critical part of the US National Space Weather Action Plan.

    For two solar activity cycles SOHO has measured the total solar irradiance (the “solar constant”) as well as variations in the extreme ultraviolet flux, both of which are important to understand the impact of solar variability on Earth’s climate.

    Besides watching the Sun, SOHO has become the most prolific discoverer of comets in astronomical history: as of late 2017, more than 3,400 comets have been found by SOHO, most of them by amateurs accessing SOHO real-time data via the Internet.

    In such complex areas of research as solar physics, progress is not limited to the work of a few people working by themselves. The scientific achievements of the SOHO mission result from a concerted, multi-disciplinary effort by a large, international community of solar scientists, including sound investments in space hardware, coupled with vigorous and well-coordinated scientific operations and interpretation efforts.

    Also, it is important to note that SOHO was not conceived as a “stand-alone” mission. Together with Cluster – a set of four identical spacecraft operated as a single experiment to explore in three dimensions the plasma and small-scale structure in the Earth’s plasma environment – SOHO formed the Solar-Terrestrial Science Programme (STSP), the first cornerstone of the European Space Agency’s long-term program called “Space Science Horizon 2000”, which was implemented in collaboration with NASA.

    4
    ESA Cluster (4 spacecraft) which work with SOHO

    STSP itself was part of an even larger international effort by NASA, ESA, and JAXA: The International Solar-Terrestrial Physics (ISTP) program, which included SOHO, Cluster, Geotail, Wind, and Polar, achieved an unprecedented understanding of the physics of solar-terrestrial relations by coordinated, simultaneous investigations of the Sun-Earth space environment over an extended period of time and, thus, can be considered the predecessor of NASA’s Living With a Star (LWS) program.

    While SOHO’s continued operation into the 2020s depends only on the longevity of its solar arrays, there is as yet no defined mission to succeed it in providing continuous, earth-Sun-line coronagraph observations. Prior to SOHO, our maximum warning time for extreme, earth-directed solar storms was measured in minutes; now it is 1 – 2 days. It would be prudent to preserve that advantage.

    See the full post here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The purpose of the American Geophysical Union is to promote discovery in Earth and space science for the benefit of humanity.

    To achieve this mission, AGU identified the following core values and behaviors.

    Core Principles

    As an organization, AGU holds a set of guiding core values:

    The scientific method
    The generation and dissemination of scientific knowledge
    Open exchange of ideas and information
    Diversity of backgrounds, scientific ideas and approaches
    Benefit of science for a sustainable future
    International and interdisciplinary cooperation
    Equality and inclusiveness
    An active role in educating and nurturing the next generation of scientists
    An engaged membership
    Unselfish cooperation in research
    Excellence and integrity in everything we do

    When we are at our best as an organization, we embody these values in our behavior as follows:

    We advance Earth and space science by catalyzing and supporting the efforts of individual scientists within and outside the membership.
    As a learned society, we serve the public good by fostering quality in the Earth and space science and by publishing the results of research.
    We welcome all in academic, government, industry and other venues who share our interests in understanding the Earth, planets and their space environment, or who seek to apply this knowledge to solving problems facing society.
    Our scientific mission transcends national boundaries.
    Individual scientists worldwide are equals in all AGU activities.
    Cooperative activities with partner societies of all sizes worldwide enhance the resources of all, increase the visibility of Earth and space science, and serve individual scientists, students, and the public.
    We are our members.
    Dedicated volunteers represent an essential ingredient of every program.
    AGU staff work flexibly and responsively in partnership with volunteers to achieve our goals and objectives.

     
  • richardmitnick 9:14 am on November 22, 2017 Permalink | Reply
    Tags: , , , , NASA TSIS 1 Total Solar Irradiance Spectral Solar Irradiance 1, Solar research   

    From Goddard: “NASA’s TSIS-1 Keeps an Eye on Sun’s Power Over Ozone” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    Nov. 21, 2017
    Rani Gran
    rani.c.gran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    NASA TSIS 1 Total Solar Irradiance Spectral Solar Irradiance 1


    TSIS-1 will be affixed to the International Space Station in December 2017 TSIS-1 operates like a sun flower: it follows the Sun, from the ISS sunrise to its sunset, which happens every 90 minutes. At sunset, it rewinds, recalibrates and waits for the next sunset.
    Credits: Courtesy NASA/LASP

    1
    Antarctic ozone hole, Oct. 10, 2017: Purple and blue represent areas of low ozone concentrations in the atmosphere; yellow and red are areas of higher concentrations. Carbon tetrachloride (CCl4), which was once used in applications such as dry cleaning and as a fire-extinguishing agent, was regulated in 1987 under the Montreal Protocol along with other chlorofluorocarbons that destroy ozone and contribute to the ozone hole over Antarctica. Credits: NASA’s Goddard Space Flight Center

    2
    The picture on the left shows a calm sun from October 2010. The right side, from October 2012, shows a much more active and varied solar atmosphere as the sun moves closer to peak solar activity, or solar maximum. NASA’s Solar Dynamics Observatory (SDO) captured both images.
    Credits: NASA’s Goddard Space Flight Center/SDO

    NASA/SDO

    High in the atmosphere, above weather systems, is a layer of ozone gas. Ozone is Earth’s natural sunscreen, absorbing the Sun’s most harmful ultraviolet radiation and protecting living things below. But ozone is vulnerable to certain gases made by humans that reach the upper atmosphere. Once there, they react in the presence of sunlight to destroy ozone molecules.

    Currently, several NASA and National Oceanic and Atmospheric Administration (NOAA) satellites track the amount of ozone in the upper atmosphere and the solar energy that drives the photochemistry that creates and destroys ozone. NASA is now ready to launch a new instrument to the International Space Station that will provide the most accurate measurements ever made of sunlight as seen from above Earth’s atmosphere — an important component for evaluating the long-term effects of ozone-destroying chemistry. The Total and Spectral solar Irradiance Sensor (TSIS-1) will measure the total amount of sunlight that reaches the top of Earth’s atmosphere and how that light is distributed between different wavelengths, including ultraviolet wavelengths that we cannot sense with our eyes, but are felt by our skin and harmful to our DNA.

    This is not the first time NASA has measured the total light energy from the Sun. TSIS-1 succeeds previous and current NASA missions to monitor incoming sunlight with technological upgrades that should improve stability, provide three times better accuracy and lower interference from other sources of light, according to Candace Carlisle, TSIS-1 project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    “We need to measure the full spectrum of sunlight and the individual wavelengths to evaluate how the Sun affects Earth’s atmosphere,” said Dong Wu, TSIS-1 project scientist at Goddard.

    TSIS-will see more than 1,000 wavelength bands from 200 to 2400 nanometers. The visible part of the spectrum our eyes see goes from about 390 nanometers (blue) to 700 nanometers (red). A nanometer is one billionth of a meter.

    “Each color or wavelength of light affects Earth’s atmosphere differently,” Wu said.

    TSIS-1 will see different types of ultraviolet (UV) light, including UV-B and UV-C. Each plays a different role in the ozone layer. UV-C rays are essential in creating ozone. UV-B rays and some naturally occurring chemicals regulate the abundance of ozone in the upper atmosphere. The amount of ozone is a balance between these natural production and loss processes. In the course of these processes, UV-C and UV-B rays are absorbed, preventing them from reaching Earth’s surface and harming living organisms. Thinning of the ozone layer has allowed some UV-B rays to reach the ground.

    In the 1970s, scientists theorized that certain human-made chemicals found in spray cans, air conditioners and refrigerators could throw off the natural balance of ozone creation and depletion and cause an unnatural depletion of the protective ozone. In the 1980s, scientists observed ozone loss consistent with the concentrations of these chemicals and confirmed this theory.

    Ozone loss was far more severe than expected over the South Pole during the Antarctic spring (fall in the United States), a phenomenon that was named “the Antarctic ozone hole.” The discovery that human-made chemicals could have such a large effect on Earth’s atmosphere brought world leaders together. They created an international commitment to phase out ozone-depleting chemicals called the Montreal Protocol, which was universally ratified in 1987 by all countries that participate in the United Nations, and has been updated to tighten constraints and account for additional ozone depleting chemicals.

    A decade after the ratification of the Montreal Protocol, the amount of human-made ozone-destroying chemicals in the atmosphere peaked and began a slow decline. However, it takes decades for these chemicals to completely cycle out of the upper atmosphere, and the concentrations of these industrially produced molecules are not all decreasing as expected, while additional, new compounds are being created and released.

    More than three decades after ratification, NASA satellites have verified that ozone losses have stabilized and, in some specific locations, have even begun to recover due to reductions in the ozone-destroying chemicals regulated under the Montreal Protocol.

    As part of their work in monitoring the recovery of the ozone hole, scientists use computer models of the atmosphere that simulate the physical, chemical and weather processes in the atmosphere. These atmospheric models can then take input from ground and satellite observations of various atmospheric gases, both natural and human-produced, to help predict ozone layer recovery. They test the models by simulating past changes and then compare the results with satellite measurements to see if the simulations match past outcomes. To run the best possible simulation, the models also need accurate measurements of sunlight across the spectrum.

    “Atmospheric models need accurate measurements of sunlight across the to model the ozone layer correctly,” said Peter Pilewskie, TSIS-1 lead scientist at the Laboratory for Atmospheric and Space Physics in Boulder, Colorado. Scientists have learned that variations in UV radiance produce significant changes in the results of the computer simulations.

    Overall, solar energy output varies by approximately 0.1 percent — or about 1 watt per square meter between the most and least active part of an 11-year solar cycle. The solar cycle is marked by the alternating high and low activity periods of sunspots, dark regions of complex magnetic activity on the Sun’s surface. While UV light represents a tiny fraction of the total sunlight that reaches the top of Earth’s atmosphere, it fluctuates much more, anywhere from 3 to 10 percent, a change that in turn causes small changes in the chemical composition and thermal structure of the upper atmosphere.

    That’s where TSIS-1 comes in. “[TSIS] measurements of the solar spectrum are three times more accurate than previous instruments,” said Pilewskie. Its high quality measurements will allow scientists to fine tune their computer models and produce better simulations of the ozone layer’s behavior — as well as other atmospheric processes influenced by sunlight, such as the movement of winds and weather that are.

    TSIS-1 joins a fleet of NASA’s Earth-observing missions that monitor nearly every aspect of the Earth system, watching for any changes in our environment that could harm life.

    For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future by deploying space based sensors like TSIS-1. NASA’s Goddard Space Flight Center has overall responsibility for the development and operation of TSIS-1 on International Space Station as part of the Earth Systematic Missions program. The Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, under contract with NASA, is responsible for providing the TSIS-1 measurements and ensuring their availability to the scientific community.

    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 12:38 pm on October 9, 2017 Permalink | Reply
    Tags: , , , , , Explosions on the sun’s surface explain its extremely hot outermost layers, , Solar research   

    From Science: “Explosions on the sun’s surface explain its extremely hot outermost layers” 

    AAAS
    Science

    Oct. 9, 2017
    Katherine Kornei

    1
    NASA/JPL-Caltech/GSFC

    This summer’s total solar eclipse revealed rare views of the sun’s corona, its outermost layers of plasma millions of degrees in temperature. But the solar corona has long baffled scientists: Why is it so searingly hot compared with the sun’s visible surface, which is about 1000 times cooler? Now, researchers have suggested that relatively small explosions known as “nanoflares” may be responsible for the corona’s extreme temperatures. Working in the New Mexico desert, the scientists launched a sounding rocket called FOXSI containing seven telescopes on a 15-minute trip into space to observe the sun (shown above in x-ray light).

    2
    NASA FOXSI soounding rocket

    The telescopes, with more sensitive detectors than previous x-ray telescopes, recorded high-energy light indicative of temperatures exceeding 10 million°C from one region of the sun. But solar flares—the brief, intense flashes of light caused by the sun’s magnetic fields changing shape suddenly—couldn’t be causing the heating because none were observed. Instead, many nanoflares, a million times weaker than traditional solar flares but still packing enough of a punch to meet the United States’ energy needs for a year, were acting in concert to heat the corona, the team reports today in Nature Astronomy. Upcoming FOXSI launches and other space-based telescopes may reveal more about nanoflares, the researchers suggest.

    See the full article here .

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  • richardmitnick 8:44 pm on October 6, 2017 Permalink | Reply
    Tags: A mission to the Sun first recommended in 1958 is set to launch in 2018, , ISIS-Integrated Scientific Investigation of the Sun instrument suite, , Solar research   

    From Eos: “Solar Probe Will Approach Sun Closer Than Any Prior Spacecraft” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    4 October 2017
    Randy Showstack

    NASA Parker Solar Probe Plus

    A mission to the Sun first recommended in 1958 is set to launch in 2018, 6 decades later. NASA’s Parker Solar Probe, which the agency plans to send to space next summer for a nearly 7-year journey, will fly within 4 million miles (6.4 million kilometers) of the Sun’s surface, more than 7 times closer than any other satellite. There, it will help scientists seek answers to fundamental questions about our star such as why its outer atmosphere, or corona, is several hundreds of times hotter than the photosphere, or the Sun’s surface.

    The mission “is a real voyage of discovery,” said Nicola Fox, project scientist for the probe at Johns Hopkins University’s Applied Physics Laboratory (APL) in Laurel, Md. “We’ve been to every major planet, but we’ve never managed to go up into the corona.” Until recently, we haven’t had the technology needed for a spacecraft to fly so close to the Sun and survive, Fox noted.

    She spoke with Eos in an interview last week in a clean room at APL where the probe was temporarily housed in its full flight configuration. APL is implementing the mission for NASA.

    Although scientists have learned a great deal about the Sun from remote sensing and from other spacecraft operating within the outward flow of energetic, charged particles from the Sun known as the solar wind, “you really need to get into [the solar atmosphere] to be able to answer the fundamental questions,” said Fox, who is a member of the Eos Editorial Advisory Board.

    In addition to probing why the corona sizzles at temperatures about 300 times higher those at the surface, the mission aims to explore “why in this region the solar wind suddenly gets so energized that it can actually break away from the pull of the Sun and move out at millions of miles an hour to bathe all of the planets,” Fox added. Entering the envelope of hot plasma surrounding the star may also help researchers understand more about high-energy solar particles.

    Technological Advances

    The probe is named for astrophysicist Eugene Parker, professor emeritus at the University of Chicago, who in 1958 wrote a paper about what is now referred to as the solar wind and whose work underpins a great deal of our knowledge about how stars interact with planets. In the decades since a committee of the National Academy of Sciences recommended the mission, improvements in thermal protection technology have made it possible to shield the spacecraft and its suite of instruments from the intense radiation and heat from the Sun.

    On 21 September, scientists lowered an 11.43-centimeter-thick carbon composite heat shield onto the probe to test its alignment and ensure that it will shade the craft and keep the instruments safe in the harsh environment. Those instruments will study the Sun’s electric and magnetic fields, plasma, and energetic particles and image the solar wind.

    “Everything lives in the shadow” created by the heat shield that will always be oriented to face toward the Sun, said James Kinnison of APL, a mission system engineer for the space probe who also spoke with Eos in the clean room. With the heat shield forming a cone-shaped shadow, “all the electronics stay at normal temperature [and] nothing gets really hot as long as the heat shield is pointed toward the Sun,” he said.

    1
    Engineers at APL lowered the heat shield onto the Parker Solar Probe spacecraft last month to test alignment. Credit: NASA/JHUAPL, CC BY 2.0

    Because the spacecraft will often need to operate autonomously when it is behind the Sun or subject to communication delays because of its distance from Earth, the probe includes a system to detect and quickly recover from even a slight misalignment of its axis.

    “If it starts tilting, for instance, that would be a problem that would have to be detected very quickly, and you want to recover from that,” said Kinnison. “We do an awful lot of testing on the spacecraft here on Earth before we launch to know that that’s going to work. We’re very certain that it will work.”

    The development of solar power arrays able to withstand the intense solar environment has also enabled the mission, Kinnison said. The probe will operate on about 350 watts of power for all of its science and engineering needs, including collecting scientific measurements and downlinking data. Aside from the solar array and the heat shield, most of the spacecraft’s other components are “relatively normal,” he said.

    Space Weather

    Fox and others noted that the mission, which has a launch window from 31 July to 19 August 2018, could help scientists to better understand how outbursts of energy and particles from the Sun, known as space weather, affect Earth. “We can have beautiful aurora. We can also have catastrophic events,” Fox said. “Until you go up and really understand what’s going on in that region, you really can’t do a better job of predicting what’s going to hit the Earth. So [the mission] is important for fundamental science, but it has very real world impacts.”

    It could lead to “transformational changes to the models that we use to predict space weather,” she added.

    Eric Christian, deputy principal investigator for the solar probe’s Integrated Scientific Investigation of the Sun (ISIS) instrument suite, told Eos that the Sun’s activities can affect the power grid and human and satellite operations in space.

    Just as terrestrial weather forecasting has gotten better, space weather forecasting also needs to improve, he contended.

    “If we want to spread throughout the solar system with robots and manned missions,” Christian said, “we’re going to need to understand [the Sun and space weather] better.”

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 9:01 am on October 2, 2017 Permalink | Reply
    Tags: , , , , , , Solar research   

    From ESA: “Facing the Sun” 

    ESA Space For Europe Banner

    European Space Agency

    Released 02/10/2017 9:00 am
    ESA/ATG medialab; Sun: NASA/SDO/ P. Testa (CfA)

    1
    An artist’s impression of Solar Orbiter in front of the stormy Sun is depicted here. No image credit

    Now being fitted with its state-of-the-art instruments, ESA’s Solar Orbiter is set to provide new views of our star, in particular providing close-up observations of the Sun’s poles.

    NASA/ESA Solar Orbiter

    Following its launch in February 2019 and three-year journey using gravity swingbys at Earth and Venus, Solar Orbiter will operate from an elliptical orbit around the Sun. At its closest it will approach our star within 42 million kilometres, closer than planet Mercury.

    An artist’s impression of Solar Orbiter in front of the stormy Sun is depicted here. The image of the Sun is based on one taken by NASA’s Solar Dynamics Observatory.

    NASA/SDO

    It captures the beginning of a solar eruption that took place on 7 June 2011. At lower right, dark filaments of plasma arc away from the Sun. During this particular event, it watched the plasma lift off, then rain back down to create ‘hot spots’ that glowed in ultraviolet light.

    Solar Orbiter’s over-arching mission goals are to examine how the Sun creates and controls the heliosphere, the extended atmosphere of the Sun in which we reside, and the effects of solar activity on it. The spacecraft will combine in situ and remote sensing observations close to the Sun to gain new information about solar activity and how eruptions produce energetic particles, what drives the solar wind and the coronal magnetic field, and how the Sun’s internal dynamo works.

    Its 10 scientific instruments are in the final stages of being added to the spacecraft before extensive tests to prepare it for the 2019 launch from Cape Canaveral, USA.

    Solar Orbiter is an ESA-led mission with NASA participation.

    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.

    ESA50 Logo large

     
  • richardmitnick 7:11 pm on September 26, 2017 Permalink | Reply
    Tags: , , , , , , Solar research   

    From NRAO: “Image Release: ALMA Reveals Sun in New Light” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    ESO/NRAO/NAOJ ALMA Array

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres
    ALMA

    1
    This ALMA image of an enormous sunspot was taken on 18 December 2015 with the Band 6 receiver at a wavelength of 1.25 millimeters. Sunspots are transient features that occur in regions where the Sun’s magnetic field is extremely concentrated and powerful. They are lower in temperature than their surrounding regions, which is why they appear relatively dark in visible light. The ALMA image is essentially a map of temperature differences in a layer of the Sun’s atmosphere known as the chromosphere, which lies just above the visible surface of the Sun (the photosphere). The chromosphere is considerably hotter than the photosphere. Understanding the heating and dynamics of the chromosphere are key areas of research that will be addressed by ALMA. Observations at shorter wavelengths probe deeper into the solar chromosphere than longer wavelengths. Hence, band 6 observations map a layer of the chromosphere that is closer to the visible surface of the Sun than band 3 observations.Credit: ALMA (ESO/NAOJ/NRAO)

    New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal stunning details of our Sun, including the dark, contorted center of an evolving sunspot that is nearly twice the diameter of the Earth.

    These images are part of the testing and verification campaign to make ALMA’s solar observing capabilities available to the international astronomical community.

    Though designed principally to observe remarkably faint objects throughout the universe — such as distant galaxies and planet-forming disks around young stars – ALMA is also capable of studying objects in our own solar system, including planets, comets, and now the Sun.

    During a 30-month period beginning in 2014, an international team of astronomers harnessed ALMA’s single-antenna and array capabilities to detect and image the millimeter-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, the visible surface of the Sun.

    These new images demonstrate ALMA’s ability to study solar activity at longer wavelengths than observed with typical solar telescopes on Earth, and are an important expansion of the range of observations that can be used to probe the physics of our nearest star.

    “We’re accustomed to seeing how our Sun appears in visible light, but that can only tell us so much about the dynamic surface and energetic atmosphere of our nearest star,” said Tim Bastian, an astronomer with the National Radio Astronomy Observatory in Charlottesville, Va. “To fully understand the Sun, we need to study it across the entire electromagnetic spectrum, including the millimeter and submillimeter portion that ALMA can observe.”

    Since our Sun is many billions of times brighter than the faint objects ALMA typically observes, the solar commissioning team had to developed special procedures to enable ALMA to safely image the Sun.

    The result of this work is a series of images that demonstrates ALMA’s unique vision and ability to study our Sun on multiple scales.

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 11:10 am on August 12, 2017 Permalink | Reply
    Tags: , , , , , , Solar core spins four times faster than expected, Solar research   

    From physicsworld.com: “Solar core spins four times faster than expected” 

    physicsworld
    physicsworld.com

    Aug 11, 2017
    Keith Cooper

    1
    Sunny science: the Sun still holds some mysteries for researchers. No image credit.

    The Sun’s core rotates four times faster than its outer layers – and the elemental composition of its corona is linked to the 11 year cycle of solar magnetic activity. These two findings have been made by astronomers using a pair of orbiting solar telescopes – NASA’s Solar Dynamics Observatory (SDO) and the joint NASA–ESA Solar and Heliospheric Observatory (SOHO). The researchers believe their conclusions could revolutionize our understanding of the Sun’s structure.

    NASA/SDO

    ESA/NASA SOHO

    Onboard SOHO is an instrument named GOLF (Global Oscillations at Low Frequencies) – designed to search for millimetre-sized gravity, or g-mode, oscillations on the Sun’s surface (the photosphere). Evidence for these g-modes has, however, proven elusive – convection of energy within the Sun disrupts the oscillations, and the Sun’s convective layer exists in its outer third. If solar g-modes exist then they do so deep within the Sun’s radiative core.

    A team led by Eric Fossat of the Université Côte d’Azur in France has therefore taken a different tack. The researchers realized that acoustic pressure, or p-mode, oscillations that penetrate all the way through to the core – which Fossat dubs “solar music” – could be used as a probe for g-mode oscillations. Assessing over 16 years’ worth of observations by GOLF, Fossat’s team has found that p-modes passing through the solar core are modulated by the g-modes that reverberate there, slightly altering the spacing between the p-modes.

    Fossat describes this discovery as “a fantastic result”, in terms of what g-modes can tell us about the solar interior. The properties of the g-mode oscillations depend strongly on the structure and conditions within the Sun’s core, including the ratio of hydrogen to helium, and the period of the g-modes indicate that the Sun’s core rotates approximately once per week. This is around four times faster than the Sun’s outer layers, which rotate once every 25 days at the equator and once every 35 days at the poles.

    Diving into noise

    Not everyone is convinced by the results. Jeff Kuhn of the University of Hawaii describes the findings as “interesting”, but warns that independent verification is required.

    “Over the last 30 years there have been several claims for detecting g-modes, but none have been confirmed,” Kuhn told physicsworld.com. “In their defence, [Fossat’s researchers] have tried several different tests of the GOLF data that give them confidence, but they are diving far into the noise to extract this signal.” He thinks that long-term ground-based measurements of some p-mode frequencies should also contain the signal and confirm Fossat’s findings further.

    If the results presented in Astronomy & Astrophysics can be verified, then Kuhn is excited about what a faster spinning core could mean for the Sun. “It could pose some trouble for our basic understanding of the solar interior,” he says. When stars are born, they are spinning fast but over time their stellar winds rob their outer layers of angular momentum, slowing them down. But Fossat suggests that conceivably their cores could somehow retain their original spin rate.

    Solar links under scrutiny

    Turning attention from the Sun’s core to its outer layers reveals another mystery. The energy generated by nuclear reactions in the Sun’s core ultimately powers the activity in the Sun’s outer layers, including the corona. But the corona is more than a million degrees hotter than the layers of the chromosphere and photosphere below it. The source of this coronal heating is unknown, but a new paper published in Nature Communications has found a link between the elemental composition of the corona, which features a broad spectrum of atomic nuclei including iron and neon, and the Sun’s 11 year cycle of magnetic activity.

    Observations made by SDO between 2010 (when the Sun was near solar minimum) and 2014 (when its activity peaked) revealed that when at minimum, the corona’s composition is dominated by processes of the quiet Sun. However, when at maximum the corona’s composition is instead controlled by some unidentified process that takes place around the active regions of sunspots.

    That the composition of the corona is not linked to a fixed property of the Sun (such as its rotation) but is instead connected to a variable property, could “prompt a new way of thinking about the coronal heating problem,” says David Brooks of George Mason University, USA, who is lead author on the paper. This is because the way in which elements are transported into the corona is thought to be closely related to how the corona is being heated.

    Quest for consensus

    Many explanations for the corona’s high temperature have been proposed, ranging from magnetic reconnection to fountain-like spicules, and magnetic Alfvén waves to nanoflares, but none have yet managed to win over a consensus of solar physicists.

    “If there’s a model that explains everything – the origins of the solar wind, coronal heating and the observed preferential transport – then that would be a very strong candidate,” says Brooks. The discovery that the elemental abundances vary with the magnetic cycle is therefore a new diagnostic against which to test models of coronal heating.

    See the full article here .

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    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
    IOP Institute of Physics

     
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