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  • 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.

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  • 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.
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  • richardmitnick 9:42 am on August 2, 2017 Permalink | Reply
    Tags: , , , , , , Solar research   

    From ESA: “Gravity waves detected in Sun’s interior reveal rapidly rotating core” 

    ESA Space For Europe Banner

    European Space Agency

    1 August 2017

    Eric Fossat
    Laboratoire Lagrange
    Université Côte d’Azur
    Observatoire de la Côte d’Azur, France
    Email: Eric.Fossat@oca.eu

    Bernhard Fleck
    ESA SOHO Project Scientist
    Email: bfleck@esa.nascom.nasa.gov

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

    1
    Solar interior. No image credit.

    Scientists using the ESA/NASA SOHO solar observatory have found long-sought gravity modes of seismic vibration that imply the Sun’s core is rotating four times faster than its surface.

    2
    ESA/NASA SOHO

    Just as seismology reveals Earth’s interior structure by the way in which waves generated by earthquakes travel through it, solar physicists use ‘helioseismology’ to probe the solar interior by studying sound waves reverberating through it. On Earth, it is usually one event that is responsible for generating the seismic waves at a given time, but the Sun is continuously ‘ringing’ owing to the convective motions inside the giant gaseous body.

    Higher frequency waves, known as pressure waves (or p-waves), are easily detected as surface oscillations owing to sound waves rumbling through the upper layers of the Sun. They pass very quickly through deeper layers and are therefore not sensitive to the Sun’s core rotation.

    Conversely, lower frequency gravity waves (g-waves) that represent oscillations of the deep solar interior have no clear signature at the surface, and thus present a challenge to detect directly.

    In contrast to p-waves, for which pressure is the restoring force, buoyancy (gravity) acts as the restoring force of the gravity waves.

    “The solar oscillations studied so far are all sound waves, but there should also be gravity waves in the Sun, with up-and-down, as well as horizontal motions like waves in the sea,” says Eric Fossat, lead author of the paper describing the result, published in Astronomy & Astrophysics.

    “We’ve been searching for these elusive g-waves in our Sun for over 40 years, and although earlier attempts have hinted at detections, none were definitive. Finally, we have discovered how to unambiguously extract their signature.”

    Eric and his colleagues used 16.5 years of data collected by SOHO’s dedicated ‘Global Oscillations at Low Frequencies’ (GOLF) instrument. By applying various analytical and statistical techniques, a regular imprint of the g-modes on the p-modes was revealed.

    In particular, they looked at a p-mode parameter that measures how long it takes for an acoustic wave to travel through the Sun and back to the surface again, which is known to be 4 hours 7 minutes. A series of modulations was detected in this p-mode parameter that could be interpreted as being due to the g-waves shaking the structure of the core.

    The signature of the imprinted g-waves suggests the core is rotating once every week, nearly four times faster than the observed surface and intermediate layers, which vary from 25 days at the equator to 35 days at the poles.

    “G-modes have been detected in other stars, and now thanks to SOHO we have finally found convincing proof of them in our own star,” adds Eric. “It is really special to see into the core of our own Sun to get a first indirect measurement of its rotation speed. But, even though this decades long search is over, a new window of solar physics now begins.”

    The rapid rotation has various implications, for example: is there any evidence for a shear zone between the differently rotating layers? What do the periods of the g-waves tell us about the chemical composition of the core? What implication does this have on stellar evolution and the thermonuclear processes in the core?

    “Although the result raises many new questions, making an unambiguous detection of gravity waves in the solar core was the key aim of GOLF. It is certainly the biggest result of SOHO in the last decade, and one of SOHO’s all-time top discoveries,” says Bernhard Fleck, ESA’s SOHO project scientist.

    ESA’s upcoming solar mission, Solar Orbiter will also ‘look’ into the solar interior but its main focus is to provide detailed insights into the Sun’s polar regions, and solar activity. Meanwhile ESA’s future planet-hunting mission, Plato, will investigate seismic activity in stars in the exoplanet systems it discovers, adding to our knowledge of relevant processes in Sun-like stars.

    NASA/ESA Solar Orbiter

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    ESA > Our Activities > Space Science >

    Solar interior
    1 August 2017

    Scientists using the ESA/NASA SOHO solar observatory have found long-sought gravity modes of seismic vibration that imply the Sun’s core is rotating four times faster than its surface.

    Just as seismology reveals Earth’s interior structure by the way in which waves generated by earthquakes travel through it, solar physicists use ‘helioseismology’ to probe the solar interior by studying sound waves reverberating through it. On Earth, it is usually one event that is responsible for generating the seismic waves at a given time, but the Sun is continuously ‘ringing’ owing to the convective motions inside the giant gaseous body.

    Higher frequency waves, known as pressure waves (or p-waves), are easily detected as surface oscillations owing to sound waves rumbling through the upper layers of the Sun. They pass very quickly through deeper layers and are therefore not sensitive to the Sun’s core rotation.

    Conversely, lower frequency gravity waves (g-waves) that represent oscillations of the deep solar interior have no clear signature at the surface, and thus present a challenge to detect directly.

    In contrast to p-waves, for which pressure is the restoring force, buoyancy (gravity) acts as the restoring force of the gravity waves.

    “The solar oscillations studied so far are all sound waves, but there should also be gravity waves in the Sun, with up-and-down, as well as horizontal motions like waves in the sea,” says Eric Fossat, lead author of the paper describing the result, published in Astronomy & Astrophysics.
    SOHO

    “We’ve been searching for these elusive g-waves in our Sun for over 40 years, and although earlier attempts have hinted at detections, none were definitive. Finally, we have discovered how to unambiguously extract their signature.”

    Eric and his colleagues used 16.5 years of data collected by SOHO’s dedicated ‘Global Oscillations at Low Frequencies’ (GOLF) instrument. By applying various analytical and statistical techniques, a regular imprint of the g-modes on the p-modes was revealed.

    In particular, they looked at a p-mode parameter that measures how long it takes for an acoustic wave to travel through the Sun and back to the surface again, which is known to be 4 hours 7 minutes. A series of modulations was detected in this p-mode parameter that could be interpreted as being due to the g-waves shaking the structure of the core.

    The signature of the imprinted g-waves suggests the core is rotating once every week, nearly four times faster than the observed surface and intermediate layers, which vary from 25 days at the equator to 35 days at the poles.

    “G-modes have been detected in other stars, and now thanks to SOHO we have finally found convincing proof of them in our own star,” adds Eric. “It is really special to see into the core of our own Sun to get a first indirect measurement of its rotation speed. But, even though this decades long search is over, a new window of solar physics now begins.”

    The rapid rotation has various implications, for example: is there any evidence for a shear zone between the differently rotating layers? What do the periods of the g-waves tell us about the chemical composition of the core? What implication does this have on stellar evolution and the thermonuclear processes in the core?

    “Although the result raises many new questions, making an unambiguous detection of gravity waves in the solar core was the key aim of GOLF. It is certainly the biggest result of SOHO in the last decade, and one of SOHO’s all-time top discoveries,” says Bernhard Fleck, ESA’s SOHO project scientist.

    ESA’s upcoming solar mission, Solar Orbiter will also ‘look’ into the solar interior but its main focus is to provide detailed insights into the Sun’s polar regions, and solar activity. Meanwhile ESA’s future planet-hunting mission, Plato, will investigate seismic activity in stars in the exoplanet systems it discovers, adding to our knowledge of relevant processes in Sun-like stars.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

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

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  • richardmitnick 9:06 am on June 23, 2017 Permalink | Reply
    Tags: , , Scientists Uncover Origins of the Sun’s Swirling Spicules, Solar research, Swedish 1-meter Solar Telescope in La Palma Spain   

    From Goddard: “Scientists Uncover Origins of the Sun’s Swirling Spicules” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    June 22, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    No image caption or credit.

    At any given moment, as many as 10 million wild jets of solar material burst from the sun’s surface. They erupt as fast as 60 miles per second, and can reach lengths of 6,000 miles before collapsing. These are spicules, and despite their grass-like abundance, scientists didn’t understand how they form. Now, for the first time, a computer simulation — so detailed it took a full year to run — shows how spicules form, helping scientists understand how spicules can break free of the sun’s surface and surge upward so quickly.

    This work relied upon high-cadence observations from NASA’s Interface Region Imaging Spectrograph, or IRIS, and the Swedish 1-meter Solar Telescope in La Palma, in the Canary Islands. Together, the spacecraft and telescope peer into the lower layers of the sun’s atmosphere, known as the interface region, where spicules form. The results of this NASA-funded study were published in Science on June 22, 2017 — a special time of the year for the IRIS mission, which celebrates its fourth anniversary in space on June 26.

    NASA IRIS spacecraft

    2
    Swedish 1-meter Solar Telescope in La Palma, in the Canary Islands, Spain


    Watch the video to learn how scientists used a combination of computer simulations and observations to determine how spicules form.
    Credits: NASA’s Goddard Space Flight Center/Joy Ng, producer

    “Numerical models and observations go hand in hand in our research,” said Bart De Pontieu, an author of the study and IRIS science lead at Lockheed Martin Solar and Astrophysics Laboratory, in Palo Alto, California. “We compare observations and models to figure out how well our models are performing, and to improve the models when we see major discrepancies.”

    Observing spicules has been a thorny problem for scientists who want to understand how solar material and energy move through and away from the sun. Spicules are transient, forming and collapsing over the course of just five to 10 minutes. These tenuous structures are also difficult to study from Earth, where the atmosphere often blurs our telescopes’ vision.

    A team of scientists has been working on this particular model for nearly a decade, trying again and again to create a version that would create spicules. Earlier versions of the model treated the interface region, the lower solar atmosphere, as a hot gas of electrically charged particles — or more technically, a fully ionized plasma. But the scientists knew something was missing because they never saw spicules in the simulations.

    The key, the scientists realized, was neutral particles. They were inspired by Earth’s own ionosphere, a region of the upper atmosphere where interactions between neutral and charged particles are responsible for many dynamic processes.

    The research team knew that in cooler regions of the sun, such as the interface region, not all gas particles are electrically charged. Some particles are neutral, and neutral particles aren’t subject to magnetic fields like charged particles are. Scientists had based previous models on a fully ionized plasma in order to simplify the problem. Indeed, including the necessary neutral particles was very computationally expensive, and the final model took roughly a year to run on the Pleiades supercomputer located at NASA’s Ames Research Center in Silicon Valley, and which supports hundreds of science and engineering projects for NASA missions.

    The model began with a basic understanding of how plasma moves in the sun’s atmosphere. Constant convection, or boiling, of material throughout the sun generates islands of tangled magnetic fields. When boiling carries them up to the surface and farther into the sun’s lower atmosphere, magnetic field lines rapidly snap back into place to resolve the tension, expelling plasma and energy. Out of this violence, a spicule is born. But explaining how these complex magnetic knots rise and snap was the tricky part.

    “Usually magnetic fields are tightly coupled to charged particles,” said Juan Martínez-Sykora, lead author of the study and a solar physicist at Lockheed Martin and the Bay Area Environmental Research Institute in Sonoma, California. “With only charged particles in the model, the magnetic fields were stuck, and couldn’t rise beyond the sun’s surface. When we added neutrals, the magnetic fields could move more freely.”

    Neutral particles provide the buoyancy the gnarled knots of magnetic energy need to rise through the sun’s boiling plasma and reach the chromosphere. There, they snap into spicules, releasing both plasma and energy. Friction between ions and neutral particles heats the plasma even more, both in and around the spicules.

    With the new model, the simulations at last matched observations from IRIS and the Swedish Solar Telescope; spicules occurred naturally and frequently. The 10 years of work that went into developing this numerical model earned scientists Mats Carlsson and Viggo H. Hansteen, both authors of the study from the University of Oslo in Norway, the 2017 Arctowski Medal from the National Academy of Sciences. Martínez-Sykora led the expansion of the model to include the effects of neutral particles.

    The scientists’ updated model revealed something else about how energy moves in the solar atmosphere. It turns out this whip-like process also naturally generates Alfvén waves, a strong kind of magnetic wave scientists suspect is key to heating the sun’s atmosphere and propelling the solar wind, which constantly bathes our solar system and planet with charged particles from the sun.

    “This model answers a lot of questions we’ve had for so many years,” De Pontieu said. “We gradually increased the physical complexity of numerical models based on high-resolution observations, and it is really a success story for the approach we’ve taken with IRIS.”

    The simulations indicate spicules could play a big role in energizing the sun’s atmosphere, by constantly forcing plasma out and generating so many Alfvén waves across the sun’s entire surface.

    “This is a major advance in our understanding of what processes can energize the solar atmosphere, and lays the foundation for investigations with even more detail to determine how big of a role spicules play,” said Adrian Daw, IRIS mission scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “A very nice result on the eve of our launch anniversary.”

    Related:

    IRIS Mission Overview
    New Space Weather Model Helps Simulate Magnetic Structure of Solar Storms

    See the full article here.

    Please help promote STEM in your local schools.

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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 12:00 pm on May 13, 2017 Permalink | Reply
    Tags: , , popsci.com, Solar research   

    From popsci.com: “How NASA is planning to touch the sun” 

    popsci-bloc

    Popular Science

    February 14, 2017 [Where has this been?]
    Ian Graber-Stiehl

    A look behind the scenes of NASA’s advanced solar probe

    1
    An explosion on the sun shoots fiery plasma out into space. NASA/Goddard/SDO

    Our sun might not seem as enigmatic as more exotic, distant stars, but it’s still a marvelously mysterious miasma of incandescent plasma. And it’s certainly worthy of our scientific attention: Curiosity aside, a violent solar event could disrupt satellites and cause $2 trillion in damages for the U.S. alone. Yet, despite living in its atmosphere, we don’t understand some of its defining phenomena. For sixty years, we haven’t understood why the surface is a cozy 5,500 Celsius, while the halo called the corona—several million kilometers away from the star’s surface and 12 orders of magnitude less dense—boasts a positively sizzling 1-2 million Celsius.

    To figure out why, NASA needs to fly a little closer to the sun—and touch it.

    We know that magnetic reconnection—when magnetic field lines moving in opposite directions intertwine and snap like rubber bands—propels nuclear weapon-like waves of energy away from surface. Meanwhile, magnetohydrodynamic waves—vibrating guitar string-like waves of magnetic force driven by the flow of plasma—transfer energy from the surface into corona. However, without more data, our understanding of phenomena like coronal heating and solar wind acceleration remain largely theoretical…but not for long.

    Launching in 2018, NASA’s Solar Probe Plus will travel nearly seven years, setting a new record for fastest moving object as it zips 37.6 million kilometers closer to the sun than any spacecraft that has ever studied our host star.

    2
    Artist’s impression of NASA’s Solar Probe Plus spacecraft on approach to the sun. Set to launch in 2018, Solar Probe Plus will orbit the sun 24 times, closing in with the help of seven Venus flybys. The spacecraft will carry 10 science instruments specifically designed to solve two key puzzles of solar physics: why the sun’s outer atmosphere is so much hotter than the sun’s visible surface, and what accelerates the solar wind that affects Earth and our solar system.
    Date 4 December 2008
    Source http://www.jhuapl.edu/newscenter/pressreleases/2014/140318.asp
    Author NASA/Johns Hopkins University Applied Physics Laboratory

    But what manner of sensory equipment does one bring to Dante’s Inferno?

    3
    From top left: the FIELDS experiment, ISIS, WISPR, SWEAP NASA/Johns Hopkins University Applied Physics Laboratory

    Spacecraft systems engineer Mary Kae Lockwood tells PopSci that the craft will rely on four main instruments. The Solar Wind Electrons Alphas and Protons systems, or SWEAP, will monitor charges created by colliding electrons, protons and helium ions to analyze solar wind—ninety times closer to the sun than previous attempts. Similarly, the ISIS (Integrated Science Investigation of the Sun) employs a state-of-the-art detection system to analyze energetic particles (think: cancer-causing, satellite-disabling particles).

    The FIELDS sensor, meanwhile, will analyze electric and magnetic fields, radio emissions, and shock waves—while gathering information on the high-speed dust particles sanding away at the craft using a technique discovered by accident. Lastly, the Wide-field Imager for Solar Probe, or WISPR telescope, will make 3D, cat-scan-like images of solar wind and the sun’s atmosphere.

    There’s just one problem. Between intense heat, solar radiation, high-energy particles, the fallout of solar storms, dust, and limited communication opportunities at closest approach, all that sensitive equipment is going to an environment that almost makes Juno’s new home look sympathetic by comparison.

    “One of the things we had to watch out for in the design,” according to Lockwood, was the electrical “charging” of the spacecraft by the solar wind. The probe has to be conductive “so that the instruments that are actually measuring the solar wind don’t have interference.”

    4
    The probe’s planned trajectory. NASA/Johns Hopkins University Applied Physics Laboratory

    To get close enough to worry about that, though, the probe’s has to “lose some energy” says Lockwood, performing several Venus flybys to shrink its orbit “[allowing] us to get . . . closer and closer to the sun.”

    However, that comes with “interesting design challenges, because you’re not only going into the sun” as heatshield mechanical engineer Beth Congdon tells PopSci. “You get hot on approach, and then come out and get cold,” over and over for 7 flybys and 24 orbits. “You actually need to have it cyclically survive hot and cold temperatures.” And high energy particles. And hypervelocity dust. For that, you need a heat shield “different from any other heat shield that has ever existed.”

    5
    NASA/Johns Hopkins University Applied Physics Laboratory

    The incandescent elephant in the room

    “A lot of heat shields you typically think about, like the shuttle . . . They have a few minutes maximum of that kind of heat.” But at the probe’s closest approach of 5.9 million kilometers, Congdon says, temperatures will reach up to 1,377 Celsius for a full day.

    But carbon can come to the rescue. “On Earth, carbon likes to oxidise and make barbeque,” chimes Congdon, “[but] in the vacuum of space, it’s a great material for high temperature applications. The probe’s shield is made of carbon foam, sandwiched between layers of carbon composite, with a reflective ceramic coating.

    What’s more, she says, most shields have the luxury of being attached to a vibration-dampening platform. This shield, on the other hand, had to be integrated in such a way that it could mitigate vibration without one “so that we could keep the whole system as low mass as possible.” The slim, trim, and ultralight build, however, makes it challenging to keep all the sensitive equipment hidden safely behind it.

    To that end, the craft is outfitted with solar limb sensors. These sensors would be the first thing to get illuminated if the spacecraft started drifting off-kilter, and would inform the autonomous guidance and control system that keeps all the instruments behind the thermal protection system, and which is even outfitted with a backup processor in case of any malfunctions.

    Meanwhile, the solar array, facing solar intensity 475 times greater than here on Earth—in an environment where “one degree of change, at closest approach, equals a 30 percent change in power”—will automatically retract behind the heat shield whenever it swings toward the sun. From there, it’ll be kept at a cool 160 Celsius by a network of water-filled titanium channels.

    So while the heatshield weathers a minefield of million-mile-per-hour winds and countless coronal mass ejections, the communication system scarcely able to relay information for 11 straight days, the array will be kept comfortable—all while powering an autonomous 1,345 lb scientist on the doorstep of our little cosmic neighborhood’s big, confounding catalyst.

    “Going to a place changes everything we think about a place. Just look at New Horizons and how it’s changed our thoughts, beliefs, and understanding of Pluto. We’re really excited to go and totally change our view of the sun,” says Congdon. Understanding the sun’s defining phenomena is a tantalizing goal. But first we have to contend with 143.3 million kilometers of space—and one of NASA’s most technically challenging builds, over half a century in the making.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

     
  • richardmitnick 1:03 pm on May 9, 2017 Permalink | Reply
    Tags: , , , , , RAISE (Rapid Acquisition Imaging Spectrograph Experiment), Solar research   

    From COSMOS: “A simple rocket for staring at the sun” 

    Cosmos Magazine bloc

    COSMOS

    09 May 2017
    Jana Howden

    1
    The RAISE rocket being prepared for take-off. Amir Caspi, Southwest Research Institute

    Capable of snapping 1,500 images in just five minutes, NASA’s newly launched rocket is raising the bar on studies of the sun. RAISE (Rapid Acquisition Imaging Spectrograph Experiment) is a type of sounding rocket, a relatively simple and cost-effective rocket that goes up 300 kilometres and spends 15–20 minutes making observations from above the atmosphere before returning to the ground.

    Although NASA runs several missions geared towards continuous study of the sun, this new sounding rocket, RAISE will allow researchers to study the fast processes and split-second changes occurring near the sun’s active regions.

    These active regions are areas of complex and intense magnetic activity that can cause solar flares, which spew energy and solar material into space.

    “With RAISE, we’ll read out an image every two-tenths of a second, so we can study very fast processes and changes on the sun,” explains Don Hassler, principal investigator for the RAISE mission.

    The data collected by RAISE can be used to create what’s called a spectrogram – a visual representation of the light emitted by the sun at different wavelengths. Looking at the intensity of light at these different wavelengths allows scientists to study the ways in which energy and solar material moves around the sun, and how this can evolve into solar eruptions.

    RAISE was launched on 5 May from a missile range in the US state of New Mexico, soaring to an altitude of around 296 kilometres before parachuting gently down to Earth, where the machine is to be recovered and reused.

    Read more at NASA.

    Related Links

    More about NASA’s sounding rocket program

    See the full article here .

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  • richardmitnick 4:30 pm on May 8, 2017 Permalink | Reply
    Tags: Berkeley, , , , , Solar research, Space Sciences Laboratory at University of California   

    From Goddard: “Space Weather Model Simulates Solar Storms From Nowhere” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    May 8, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Our ever-changing sun continuously shoots solar material into space. The grandest such events are massive clouds that erupt from the sun, called coronal mass ejections, or CMEs. These solar storms often come first with some kind of warning — the bright flash of a flare, a burst of heat or a flurry of solar energetic particles. But another kind of storm has puzzled scientists for its lack of typical warning signs: They seem to come from nowhere, and scientists call them stealth CMEs.

    Now, an international team of scientists, led by the Space Sciences Laboratory at University of California, Berkeley, and funded in part by NASA, has developed a model that simulates the evolution of these stealthy solar storms.


    SSL UC Berkeley campus


    Space Science Labs UC Berkeley

    The scientists relied upon NASA missions STEREO and SOHO for this work, fine-tuning their model until the simulations matched the space-based observations.

    NASA/STEREO spacecraft


    ESA/NASA SOHO

    Their work shows how a slow, quiet process can unexpectedly create a twisted mass of magnetic fields on the sun, which then pinches off and speeds out into space — all without any advance warning.

    1
    Watch the evolution of a stealth CME in this simulation. Differential rotation creates a twisted mass of magnetic fields on the sun, which then pinches off and speeds out into space. The image of the sun is from NASA’s STEREO. Colored lines depict magnetic field lines, and the different colors indicate in which layers of the sun’s atmosphere they originate. The white lines become stressed and form a coil, eventually erupting from the sun. Credits: NASA’s Goddard Space Flight Center/ARMS/Joy Ng, producer

    Compared to typical CMEs, which erupt from the sun as fast as 1800 miles per second, stealth CMEs move at a rambling gait — between 250 to 435 miles per second. That’s roughly the speed of the more common solar wind, the constant stream of charged particles that flows from the sun. At that speed, stealth CMEs aren’t typically powerful enough to drive major space weather events, but because of their internal magnetic structure they can still cause minor to moderate disturbances to Earth’s magnetic field.

    To uncover the origins of stealth CMEs, the scientists developed a model of the sun’s magnetic fields, simulating their strength and movement in the sun’s atmosphere. Central to the model was the sun’s differential rotation, meaning different points on the sun rotate at different speeds. Unlike Earth, which rotates as a solid body, the sun rotates faster at the equator than it does at its poles.

    The model showed differential rotation causes the sun’s magnetic fields to stretch and spread at different rates. The scientists demonstrated this constant process generates enough energy to form stealth CMEs over the course of roughly two weeks. The sun’s rotation increasingly stresses magnetic field lines over time, eventually warping them into a strained coil of energy. When enough tension builds, the coil expands and pinches off into a massive bubble of twisted magnetic fields — and without warning — the stealth CME quietly leaves the sun.

    Such computer models can help researchers better understand how the sun affects near-Earth space, and potentially improve our ability to predict space weather, as is done for the nation by the U.S. National Oceanic and Atmospheric Administration. A paper published in the Journal of Geophysical Research on Nov. 5, 2016, summarizes this work.

    Related

    New Space Weather Model Helps Simulate Magnetic Structure of Solar Storms
    NASA Scientists Demonstrate Technique to Improve Particle Warnings that Protect Astronauts

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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

     
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