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  • richardmitnick 2:56 pm on April 25, 2017 Permalink | Reply
    Tags: , , , , Spinning up massive classical bulges in spiral galaxies   

    From astrobites: “Spinning up massive classical bulges in spiral galaxies” 

    Astrobites bloc

    Astrobites

    Apr 25, 2017
    Sandeep Kumar Kataria – guest writer

    Title: Spin-up of massive classical bulges during secular evolution
    Authors: Kanak Saha, Ortwin Gerhard, and Inma Martinez-Valpuesta
    First Author’s Institution: Inter-University Center for Astronomy and Astrophysics, Pune
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    Status: Accepted for publication in Astronomy & Astrophysics, open access

    Introduction:

    The mass of spiral galaxies is mainly distributed in three components: the classical bulge (ClB), disc, and surrounding dark matter halo.

    Dark matter halo Image credit: Virgo consortium / A. Amblard / ESA

    Classical bulges are the central building blocks of many early-type spiral galaxies (see the Astrobites Guide to Galaxy Types). These bulges might have formed as a result of collisions between galaxies in the early universe or various other processes mentioned in this paper. It is believed that initially the motion of stars in ClBs is disordered, so the ClB does not rotate. The authors of this paper see an interesting problem to ponder: in the present day, there is an observed net rotation of stars in classical bulges. The origin of this rotation is still to be understood in detail.

    One of the authors of this paper has explained in earlier work that low-mass classical bulges spin up by absorbing angular momentum from galactic bars. The bar has a pattern speed, which is a measure of the collective rotation of a family of orbits of stars in the bar. Angular momentum exchange from the bar mainly occurs at resonances in the disc. These are locations where the difference between disc’s rotation speed and the bar pattern speed have specific ratios with radial oscillations of the stars in the disc. These resonances can be thought of as analogous to resonances in an organ pipe, the natural frequency of which corresponds to waves with wavelengths which match the length of the organ pipe. Let’s see how the authors approach the solution of the rotation problem in ClBs.

    Experiments with galaxy models using computers:

    The authors of this paper try to explain net rotations in Massive ClBs using N-Body simulations.

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    First, models of galaxies having non-rotating classical bulges of different masses and sizes are generated using well known techniques such that these models are not unstable. One of the well known classical parameters of local stability is the Toomre Parameter. This parameter measures the ratio between inward gravitational pull on stars at a particular point, and the radial motions of stars at that point. If these motions are sufficiently strong, the gravitational pull will be insufficient to overcome them and the disc will be locally stable. All the models, after evolution, form bars of different sizes according to the initial value of the Toomre parameter. Further, the point of interest lies in understanding how these bars transfer angular momentum to ClBs.

    Studying Bulge Kinematics from experiments:

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    Figure 1a. Top row – surface density maps of the model with the highest mass ClB at different times during its evolution. Second to fourth rows – line-of-sight velocity (left) and velocity dispersion (right) maps at different times. These images are taken at 90° projection (edge-on view) and the major axis of the bar is aligned with the x-axis. Clear signatures of rotation are seen at 4 Gyr. The colour bar at the top represents density, middle the velocity, and bottom the velocity dispersion.
    Figure 1b. Rotation, velocity dispersion, and local V/σ radial profiles for the four ClBs in the models.

    The authors notice changes in orbital configuration due to angular momentum transfer by the bar. From Figure 1a it can be noticed that the rotational component in the outer part of the bulge increases over time. It can also be seen that the central part of bulge becomes ‘hot’ and slightly rounder. Here ‘hot’ means that orbits of stars become more disordered and their velocity dispersion (σ) increases. Figure 1b shows radial profiles of rotation and dispersion of stars in the bulge at 4 Gyr for a few of the simulated models. It can be deduced that ClBs rotate faster in their outer parts. However, comparing simulated rotation data of ClBs with observations is no easy task: observational rotation data contains stars both in bulges and bars and distinguishing which they belong to at a single moment in time is challenging.

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    Figure 2a. Top row: distribution of bulge stars with frequency (Ω − ΩB)/κ at different times throughout the secular evolution in the model with the lowest bulge mass. Bottom row: net change in the angular momentum of the selected stars with respect to the previous time. The vertical dotted lines indicate the most important resonances (from left to right): −1:1, 4:1, 3:1, 5:2, and 2:1. As time progresses, more stars are trapped by the 2:1 resonance of the bar with the stellar disc. However, most of the angular momentum transfer occurs through the 5:2 resonance.
    Figure 2b. Here the top and bottom rows represent same entities as in the previous figure but for the models with the highest mass ClBs. As with the low mass Classical bulges most of the angular momentum transfer occurs via the 5:2 resonance.

    The Spin-up process in Massive Classical Bulges:

    After simulating galaxy models with various types of ClBs, the authors conclude that specific angular momentum (angular momentum per unit mass) transfer by the bar is the same for ClBs with low and high mass. Most of the angular momentum transfer from the disc to the bulge occur at particular locations (resonances) which are shown in Figures 2a and 2b. This phenomenon lead to density wakes (alignments of stars in the bulge with the bar) in the bulge. In the simulations density wakes are not so aligned with the bar in the low-mass ClBs but are completely aligned with the high mass ClBs by the end of simulation. The authors also find that outer parts of the bulge experience significant amount of rotation. In addition, the orbits in low-mass bulges are well-ordered, but the ones in high-mass bulges are more disordered. At the end of the simulation all models have a bar with a ‘box’ shape, suggesting that composite bulges (ClB + Boxy Bar) should be common in galaxies. Finally the authors conclude that massive ClBs, like low mass ClBs, are affected by angular momentum exchange with the bar. The spin up process is more prominent when the bar is larger than the ClB.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 2:29 pm on April 25, 2017 Permalink | Reply
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    From Eos: “What to Expect from Cassini’s Final Views of Titan” 

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    Eos

    20 April 2017
    JoAnna Wendel

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    A view of Saturn’s moon Titan accompanied by its third largest moon, Dione. The Cassini spacecraft captured this image of Titan using its narrow-angle camera in 2011, from about 2.3 million kilometers away. Scientists will soon say goodbye to future images like this one as Cassini’s mission comes to an end in September. Credit: NASA/JPL-Caltech/Space Science Institute

    NASA/ESA/ASI Cassini Spacecraft

    Since the Cassini spacecraft entered Saturn’s orbit in 2004 and dropped a probe onto its largest moon, Titan, scientists have been captivated. Titan’s icy surface is dotted with lakes and seas, its equator wrapped in a field of dunes. Its rainstorms are eerily Earth-like, and its atmosphere swells with prebiotic chemistry.

    But in a few short months, Cassini will vaporize in Saturn’s atmosphere, and scientists will wave goodbye to studying Titan up close.


    Published on Apr 4, 2017
    The final chapter in a remarkable mission of exploration and discovery, Cassini’s Grand Finale is in many ways like a brand new mission. Twenty-two times, NASA’s Cassini spacecraft will dive through the unexplored space between Saturn and its rings. What we learn from these ultra-close passes over the planet could be some of the most exciting revelations ever returned by the long-lived spacecraft. This animated video tells the story of Cassini’s final, daring assignment and looks back at what the mission has accomplished.
    For more about the making of this video, including the science behind the imagery, see the feature at https://saturn.jpl.nasa.gov/news/3016…
    The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. For more information about Cassini’s Grand Finale, please visit https://saturn.jpl.nasa.gov/grandfinale

    “It’s going to be a very emotional next several months,” said Elizabeth “Zibi” Turtle, a planetary scientist at Johns Hopkins University’s Applied Physics Laboratory (JHUAPL) in Laurel, Md. Turtle, along with about 60 other scientists inside and outside the Cassini mission, gathered at NASA’s Goddard campus in Greenbelt, Md., in early April for the fourth Titan Through Time workshop.

    There, presenters covering Titan from its interior all the way to the top of its thick atmosphere reminded us that before Cassini’s September demise, there’s still plenty of fun in store.

    On 22 April, for example, the spacecraft will sideswipe Titan and skim its ionosphere a little less than 1000 kilometers away from its surface. This flyby, designated T-126, will be Cassini’s last close trip to Titan. After 22 April, Cassini’s subsequent flybys of Titan will be from hundreds of thousands of kilometers away while it swings in and out of Saturn’s rings.

    In the past 13 years, “Titan went from being a mystery, which is exciting, to being a frontier to explore,” Turtle said. With these last views of Titan—both near and far—scientists hope to see the bottom of its lakes, improve their maps of the north pole, and even spot some storm clouds.

    A Strange Surface

    Cassini didn’t give us our first glimpse of Titan. That came from the Voyager spacecraft, which passed by Saturn in 1980 and 1981. But Voyager couldn’t see down to Titan’s surface: Those views came only with Cassini and the short-lived Huygens probe.

    NASA/Voyager 1

    ESA/Huygens Probe from Cassini landed on Titan

    During Cassini’s fourth flyby in 2005, its radar instrument revealed wind-swept dunes wrapping around Titan’s equator. Dunes are exciting because they “can be an instantaneous marker for climate and wind,” said Jani Radebaugh, a planetary scientist at Brigham Young University in Provo, Utah. A dune’s shape can, on Earth at least, reveal which way the wind is blowing.

    However, as with most things on Titan, even the discovery of dunes raised more questions. Currently, the sand looks like it’s moving one direction, but climate models show the wind is blowing in a different direction, Radebaugh said. And when observations and models don’t match up, scientists know that they should search for more clues.

    Dunes aren’t the only unexpected feature dotting Titan’s cold landscape. Early in the mission, scientists also discovered dark patches of liquid: lakes and seas. Thanks to Cassini’s infrared spectrometer and other instruments, scientists know that these lakes are filled with liquid methane, ethane, other more complex hydrocarbons, and possibly nitrogen.

    What’s more, scientists recently spotted waves on the surface of Punga Mare, a northern lake, which can tell them something about Titan’s winds and whether a future submarine exploration mission would splash or splat.

    3
    Punga Mar is a lake in the north polar region of Titan, the planet Saturn’s largest moon. After Kraken Mare and Ligeia Mare, it is the third largest known body of liquid on Titan. It is composed of liquid hydrocarbons (mainly methane and ethane). Located almost adjacent to the north pole at 85.1° N, 339.7° W, it measures roughly 380 km (236 mi) across, greater than the length of Lake Victoria on Earth. Its namesake is Punga, in Māori mythology ancestor of sharks, rays and lizards and a son of Tangaroa, the god of the sea.

    4
    A mosaic of Titan’s north polar lakes and seas stitched together from Cassini’s radar images from 2004 to 2013. Scientists are hoping that the final close-up flyby, T-126, will help them understand features on Titan’s lake beds. Credit: NASA/JPL-Caltech/ASI/USGS

    High Hopes for T-126

    Thus far, however, the angle of Titan flybys hasn’t allowed the spacecraft to see the bottoms of Titan’s smaller lakes.

    Scientists hope that T-126 will change that, said Marco Mastrogiuseppe, a telecommunications engineer at Sapienza University in Rome. During the last close flyby, Cassini scientists will aim its radar at the northern lakes to peek at their depths.

    T-126 could also help illuminate the lakes’ origins, Mastrogiuseppe said. Could they form like sinkholes on Earth, where rain and groundwater dissolve rock from above and below? Or could there be a tectonic origin, perhaps involving rifts opening basins and liquid rushing in? Scientists also suspect there could be a subsurface network connecting the lakes and seas, but they aren’t yet sure.

    Zooming Out to the Big Picture

    Even Cassini’s subsequent far-off flybys, from hundreds of thousands of kilometers away, will help scientists better understand the lakes and seas, said Conor Nixon, a planetary scientist at NASA’s Goddard Space Flight Center and one of the original cofounders of the Titan Through Time workshops.

    From up close, the radar can show scientists small patches in high resolution as the spacecraft zooms by, but it can’t get wide shots of the entire region. Imagine driving by a house at 100 kilometers per hour and snapping a picture. There isn’t much time to get a complete view. But driving by from 100 kilometers away, you’d have more time to snap multiple pictures, Nixon said.

    Similarly, during the faraway flybys, Cassini will sail over Titan’s north pole and spend hours capturing radar images of the entire region, Nixon said. These images will allow scientists to improve their maps and watch for changes along the lakes’ and seas’ shorelines.

    An Active Atmosphere

    As a scientist who works with Cassini’s remote sensing instruments, Turtle actually prefers the faraway flybys. The reason is because, from farther away, Cassini’s infrared mapping instrument and high-resolution camera can also capture a more complete profile of the atmosphere, Turtle said.

    And Titan’s atmosphere is quite the mystery. Titan is the only large moon in the solar system swaddled in a thick atmosphere, and the Huygens probe revealed that it’s dominated by nitrogen, like Earth’s. Likewise, Titan is the only other body in the solar system with liquid on its surface. Plus, Titan boasts liquid cycling akin to Earth’s hydrologic cycle, although in Titan’s case, it’s primarily methane that gets evaporated, condenses in the atmosphere, and precipitates as rainstorms that erode and shape the surface.

    But scientists have no idea how Titan’s atmosphere got there or what replenishes its nitrogen and its methane, another major constituent of the atmosphere. One particularly surprising find from Cassini was the upper atmosphere’s complex organic molecules, Turtle said. No one expected to see benzene rings or long, complex chains of hydrogen and carbon.

    Another surprising find in Titan’s upper atmosphere was heavy ions, said Sarah Hörst, an atmospheric chemist at Johns Hopkins University in Baltimore, Md. Heavy ions are key ingredients to prebiotic chemistry, which means Titan’s atmosphere could hold clues to life-generating chemistry.

    A Future Window into Titan’s Skies

    In May, scientists will recruit an Earth-based system to help them observe Titan’s atmosphere. Nixon and his team have scheduled time to observe Titan using the Atacama Large Millimeter/submillimeter Array (ALMA) observatory in northern Chile’s Atacama Desert.

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

    The May observation will match up with one of the closer of the distant Cassini flybys, Nixon said, and will allow scientists to look for an even wider range of molecules in Titan’s atmosphere. This is because some molecules can be viewed only in certain wavelengths, beyond the capabilities of Cassini’s instruments. Using ALMA will allow researchers to see molecules that might be invisible to Cassini.

    This simultaneous observation will give scientists a benchmark set of data that will allow them to continue to observe Titan’s atmosphere decades into the future, Nixon said, while they look for more prebiotic signatures, like sulfur, or a molecule called vinyl cyanide that could form cell-like membranes in Titan’s liquid oceans and lakes.

    A Portal to Data

    Even after Cassini ends, scientists will still be digging for clues, said astronomer Trina Ray from NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. Ray, along with her colleagues at JPL, has made it her mission to ensure that future scientists can use the mountains of data that Cassini has beamed to Earth.

    Cassini scientists upload their raw data into an online database called the Planetary Data System, which scientists even outside the mission can use. But these data aren’t necessarily formatted in an intuitive way for those scientists, Ray said. So she cofounded a group that is puzzling out ways to help future scientists interpret Titan data specifically. She presented at the Titan Through Time workshop to solicit input from scientists studying Titan about how to aggregate all the data.

    One of the ideas is to build a Cassini “master timeline,” Ray said, a narrative that could help guide future scientists through the mission. This timeline would include more than times, dates, and instrument information: It would include details about the intent of an activity. Why was Cassini’s camera pointing here; why was the infrared instrument pointed there?

    Ray and her team have also considered a strategy that would incorporate Titan data into a ready-to-use platform like Mars Trek, an interactive, publicly available map that layers data from various Mars missions and their landing sites. Mars Trek users can toggle between layers, explore the different sites, and save and share what they’ve found with others. Ray imagines a similar map for Titan, where scientists or users could flip through layers of data from Cassini’s different instruments.

    Mysteries Within Mysteries

    In the subsequent seven flybys of Titan before the end of Cassini, Turtle and her team will be looking for clouds over the moon’s northern hemisphere. All the climate models predict that large storm clouds should form over Titan’s high northern latitudes as Titan enters its long summer. But so far, no clouds have appeared, another sign that the hunt for clues isn’t over.

    “Titan has really been teasing us with the clouds,” Turtle said.

    Turtle may not glimpse the elusive clouds. And maybe T-126 won’t provide answers to long-standing questions about Titan’s lakes. The end of Cassini’s mission means no more sniffing the atmosphere with spectrometers, no more close-up images of meandering dunes, and no new views of its mysterious seas.

    But the workshop ended optimistically, with scientists turning their focus to a future Titan mission. Perhaps a drone-like quadcopter could fly around Titan’s surface, researchers mused, taking data from multiple research sites. Or a submarine could swim through a sea.

    And whatever new information comes to light will inevitably generate more questions.

    “That’s the other thing that’s been really fun about [studying Titan]: mysteries within mysteries,” Turtle said.

    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 11:29 am on April 25, 2017 Permalink | Reply
    Tags: , Crystalline solar cells,   

    From EPFL: “A simplified fabrication process for high efficiency solar cells” 

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    École Polytechnique Fédérale de Lausanne EPFL

    25.04.17
    Author:Mediacom / CSEM

    1
    © 2017 CSEM / David Marchon

    A team of EPFL and CSEM researchers in Neuchâtel has featured in Nature Energy with an astonishing new method for the creation of crystalline solar cells. These cells have electrical contacts at the back, which removes all shadowing at the front. Thanks to this new inexpensive approach, the fabrication process is greatly simplified, with efficiencies in the laboratory already surpassing 23%.

    In the quest for more efficient crystalline silicon solar cells with low manufacturing costs, one of the most promising approaches is to bring all electrical contacts to the back of the device. This removes all shadowing at the front, increasing the current and the efficiency. This approach generally requires several delicate processing steps. Well-defined narrow negative and positive contact lines need to be created, which will then collect the electrons (negative charges) and holes (positive charges). This usually requires several steps of photolithography masking, to create the alternate positive (+) and negative (-) areas.

    The teams at the EPFL Photovoltaics laboratory and at the CSEM PV-center succeeded in establishing an innovative process in which the positive and negative contacts align automatically. This is made possible by depositing the first “negative” contact by a plasma process through a mask. Subsequently, a second layer (positive) is deposited over the full surface. The growth of this layer is such that the negative contact, even when placed under the positive contact, remains negative.

    Using this simple process, 25 cm2 solar cells have already reached 23.2% efficiency, with a potential to reach close to 26% efficiency. The researchers are working with the Meyer Burger Company, leading equipment makers for solar cell production lines, to work out industrial solutions for this kind of solar cells, and at the same time valorizing the so-called silicon heterojunctions technology, which served as the basis for this work.

    The research was funded by the Meyer Burger Company, the Commission for Technology and Innovation (CTI) and the Swiss Federal Office of Energy (SFOE). The work will continue within the European project H2020 Nextbase.

    See the full article here .

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    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 11:17 am on April 25, 2017 Permalink | Reply
    Tags: A Practical Approach to Conservation, ,   

    From UCSB: “A Practical Approach to Conservation” 

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    UC Santa Barbara

    April 24, 2017
    Julie Cohen

    1
    No image caption. No image credit

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    Kevin Lafferty and Hillary Young. Photo Credit: Sonia Fernandez

    Is conservation good for your health? Seems like a no-brainer, right?

    Not so much, according to a group of scientists who have collaborated on a new research volume that explores what turns out to be a very tough question.

    UC Santa Barbara ecologists teamed up with colleagues at Duke University and the University of Washington to present various perspectives on the subject for the journal Philosophical Transactions of the Royal Society B. Their special issue, Conservation, Biodiversity, and Infectious Disease, is a combination of theoretical work and case studies, all of which embrace a systems approach to infectious disease ecology.

    “I’m a firm believer that insights from ecology can help us manage disease and protect species,” said co-editor Kevin Lafferty, a senior ecologist with the U.S. Geological Survey and a principal investigator at UCSB’s Marine Science Institute. “But ecological systems are too complicated to expect one-size-fits-all solutions.”

    The biodiversity-disease relationship often has been framed as a simple synergy between conservation action and improved human health, yet the links between habitat disturbance and other factors that affect disease risk are complex. The editors sought authors from diverse perspectives and backgrounds to investigate how economics, climate change and biodiversity change affect infectious diseases.

    “What’s really unique about this issue is that we have gone all the way from theory articles that look at how biodiversity changes might affect disease to multiple field studies of various conservation interventions at different scales to an examination of the global drivers of biodiversity change,” said lead editor Hillary Young, an assistant professor in UCSB’s Department of Ecology, Evolution and Marine Biology (EEMB). “We wanted to present cases for viable and useful public health interventions.”

    Take schistosomiasis, a parasitic disease carried by fresh water snails. Found predominantly in tropical and subtropical climates, schistosomiasis infects 240 million people in as many as 78 countries, with a vast majority occurring in Africa. Schistosomiasis ranks second only to malaria as the most common parasitic disease.

    Susanne Sokolow, a researcher at UCSB’s Marine Science Institute and at Stanford University’s Hopkins Marine Station, presents her study of the disease in Senegal in one paper in the special issue. She found that when dams block the migration of snail-eating river prawns, snail abundance — and presumably schistosomiasis — increase.

    “This is a story that repeats itself in systems where river prawns are present, and one that has a simple solution,” said co-author Lafferty, who is an adjunct EEMB faculty member at UCSB. “This is a type of species that can be restored and that’s the kind of win-win we’re looking for. A third win occurs because river prawn fisheries create economic benefits. Restoring the river is too vague a solution; honing in on the specific lever in the system to which the disease is sensitive gets us there faster.”

    Young’s research in Kenya, also featured in this special issue, is different, but it tells a similar story: Details matter. The ecologists examined how different types of disturbances affected vector-borne diseases and found that agricultural disturbance and the removal of large wildlife caused strong and systematic increases in many pathogens. However, pastoral land use change had no general effect.

    “The type of land use change matters; you can’t just say conservation is good for disease,” Young said. “In fact, conservations are much more effective when scientists understand the nuances involved.

    “While the mechanisms involved in my system are entirely different from the schistosomiasis system, both underscore the importance of understanding the entire ecology of the system, finding win-win scenarios and acting on them rather than expecting generalities about conservation and disease,” she added.

    Discovering the specifics can be problematic because measurements of the environment, of biodiversity and of infectious diseases vary greatly. In another of the volume’s papers, Lafferty, Young and colleagues found a way to analyze global disease burden at two time points, which enabled them to examine the same things.

    “We analyzed what drives the world’s most important infectious diseases among countries and across decades,” Lafferty explained. “It’s the most comprehensive attempt yet to explain how conservation, climate and economics affect human health.”

    The researchers considered forestation, biodiversity, wealth, temperature, precipitation and urbanization. They found that any of those factors on their own could have a positive, negative or neutral effect, depending on the disease. By far the most consistent finding, though, was this: The wealthier the country, the less disease; and the more wealth increased, the lower the burden of infectious disease.

    Young noted that this research produced a better understanding of causality than most studies. “This paper has some good news that is rarely part of the story in our field,” Lafferty said. “Our analysis shows across the board — with just a couple of exceptions — that the burden of infectious diseases has diminished considerably over the last two decades and that is mostly due to increased wealth and urbanization.”

    “There is no one-size-fits-all lever, where improving access to healthcare is going to affect all infectious diseases,” Young added. “This body of work highlights the need to understand the nuances that make biodiversity and conservation effective levers.”

    The discourse begun in the special journal will continue at the 15th annual Ecology and Evolution of Infectious Diseases conference to be held June 24-27 at UCSB. Many authors will present their work. More information is available at https://eeid2017.eemb.ucsb.edu/

    See the full article here .

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    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

     
  • richardmitnick 9:21 am on April 25, 2017 Permalink | Reply
    Tags: , , , , , SwRI-led team discovers lull in Mars’ giant impact history   

    From SwRI: “SwRI-led team discovers lull in Mars’ giant impact history” 

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    Southwest Research Institute

    April 25, 2017
    No writer credit

    1
    Mars bears the scars of five giant impacts, including the ancient giant Borealis basin (top of globe), Hellas (bottom right), and Argyre (bottom left). An SwRI-led team discovered that Mars experienced a 400-million-year lull in impacts between the formation of Borealis and the younger basins. Image Courtesy of University of Arizona/LPL/Southwest Research Institute

    From the earliest days of our solar system’s history, collisions between astronomical objects have shaped the planets and changed the course of their evolution. Studying the early bombardment history of Mars, scientists at Southwest Research Institute (SwRI) and the University of Arizona have discovered a 400-million-year lull in large impacts early in Martian history.

    This discovery is published in the latest issue of Nature Geoscience in a paper titled, “A post-accretionary lull in large impacts on early Mars.” SwRI’s Dr. Bill Bottke, who serves as principal investigator of the Institute for the Science of Exploration Targets (ISET) within NASA’s Solar System Exploration Research Virtual Institute (SSERVI), is the lead author of the paper. Dr. Jeff Andrews-Hanna, from the Lunar and Planetary Laboratory in the University of Arizona, is the paper’s coauthor.

    “The new results reveal that Mars’ impact history closely parallels the bombardment histories we’ve inferred for the Moon, the asteroid belt, and the planet Mercury,” Bottke said. “We refer to the period for the later impacts as the ‘Late Heavy Bombardment.’ The new results add credence to this somewhat controversial theory. However, the lull itself is an important period in the evolution of Mars and other planets. We like to refer to this lull as the ‘doldrums.’”

    The early impact bombardment of Mars has been linked to the bombardment history of the inner solar system as a whole. Borealis, the largest and most ancient basin on Mars, is nearly 6,000 miles wide and covers most of the planet’s northern hemisphere. New analysis found that the rim of Borealis was excavated by only one later impact crater, known as Isidis. This sets strong statistical limits on the number of large basins that could have formed on Mars after Borealis. Moreover, the preservation states of four youngest large basins — Hellas, Isidis, Argyre, and the now-buried Utopia — are strikingly similar to that of the larger, older Borealis basin. The similar preservation states of Borealis and these younger craters indicate that any basins formed in-between should be similarly preserved. No other impact basins pass this test.

    “Previous studies estimated the ages of Hellas, Isidis, and Argyre to be 3.8 to 4.1 billion years old,” Bottke said. “We argue the age of Borealis can be deduced from impact fragments from Mars that ultimately arrived on Earth. These Martian meteorites reveal Borealis to be nearly 4.5 billion years old — almost as old as the planet itself.”

    The new results reveal a surprising bombardment history for the red planet. A giant impact carved out the northern lowlands 4.5 billion years ago, followed by a lull of approximately 400 million years. Then another period of bombardment produced giant impact basins between 4.1 and 3.8 billion years ago. The age of the impact basins requires two separate populations of objects striking Mars. The first wave of impacts was associated with formation of the inner planets, followed by a second wave striking the Martian surface much later.

    SSERVI is a virtual institute headquartered at NASA’s Ames Research Center in Mountain View, California. Its members are distributed among universities and research institutes across the United States and around the world. SSERVI is working to address fundamental science questions and issues that can help further human exploration of the solar system.

    For more information, contact Deb Schmid, (210) 522-2254, Communications Department, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510.

    See the full article here .

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    Southwest Research Institute (SwRI) is an independent, nonprofit applied research and development organization. The staff of nearly 2,800 specializes in the creation and transfer of technology in engineering and the physical sciences. SwRI’s technical divisions offer a wide range of technical expertise and services in such areas as engine design and development, emissions certification testing, fuels and lubricants evaluation, chemistry, space science, nondestructive evaluation, automation, mechanical engineering, electronics, and more.

     
  • richardmitnick 8:45 am on April 25, 2017 Permalink | Reply
    Tags: An old star learns new tricks, AR Scorpii white dwarf star, , , , ,   

    From COSMOS: “An old star learns new tricks” 

    Cosmos Magazine bloc

    COSMOS

    25 April 2017
    Alan Duffy

    1

    The strange object AR Scorpii. In this unique double star a rapidly spinning white dwarf star (right) powers electrons up to almost the speed of light. M. Garlick/University of Warwick, ESA/Hubble

    When textbooks are proven wrong, we scientists can’t help but celebrate. So let’s raise a glass to the white dwarf!

    We have always dismissed these aged fellows as defunct relics of a sun-sized star. Now one has surprised us. Instead of going off gently into that good night, it is zapping the universe with a spinning beam of radiation. For astrophysicists like me, this is like hearing a retired centenarian has entered the world heavyweight boxing championships and is punching with the best of them.

    This unexpected behavior was reported in a January issue of Nature Astronomy by David Buckley at the South African Astronomical Observatory and colleagues from the University of Warwick.

    The white dwarf, AR Scorpii, and a larger companion star (a red dwarf) are located 380 light years away. Separated from each other by just three times the distance between the Earth and Moon, they orbit each other every four hours.

    Till now, if you had have asked me to describe the typical life story of a white dwarf, my explanation would have gone something like this.

    Fast-forward the next five billion years to see the Sun age before your very eyes. Its surface reddens and bloats as fusion reactions relocate to the outer layers; its shapely edges blur as its atmosphere drifts off into space. Now known as a red giant, it engulfs Mercury and Venus, almost certainly Earth and possibly Mars.

    At the end of those five billion years, the Sun’s nuclear fusion furnace has used up its fuel. Absent the outward pressure, it collapses under its own gravity.

    The result is an Earth-sized object – about one millionth its original size. After 10 billion years of fusion, the Sun is gone, the remaining carbon atoms crushed till they form a near-perfect lattice akin to a diamond. Each teaspoon’s worth of material equals a ton in mass.

    It is now a white dwarf. Though the star’s surface continues to glow white hot at more than 100,000 Kelvin, it is effectively dead, slowly fading to leave a black dwarf, with no more role to play in the evolution of the galaxy.

    AR Scorpii, however, is different. Rather than fading away, it has been acting more like a lighthouse, spinning on its axis every two minutes and emitting a tightly focused beam of radiation along its magnetic poles. Like a giant dynamo, the beam is powered by a magnetic field a 100 million times that of Earth’s.

    In emitting its regular rotating beam, AR Scorpii is behaving like a pulsar, albeit a slow one. These cosmic beacons usually spin with a period of seconds rather than minutes and were previously thought to be powered only by neutron stars, the end state of a star with a mass at least three times that of the Sun. Even more dense than a white dwarf, a teaspoonful of neutron star weighs a billion tonnes.

    Even more unusually, the beams from the feisty AR Scorpii tear across the face of its companion star, accelerating material to close to the speed of light and causing it to shine measurably brighter.

    Just how AR Scorpii acquired the superpowers of a neutron star is a mystery that has astrophysicists bemused. White dwarves are not supposed to be able to do this! Only neutron stars were thought to be able to power the pulsars seen in their thousands across the galaxy. Now we know different.

    This isn’t the first time researchers have suggested a white dwarf might not just be a silent senior citizen. In 2008, Japanese astrophysicist Yukikatsu Terada and colleagues published an article in the Publications of the Astronomical Society of Japan that showed the rapidly rotating white dwarf AE Aquarii was pulsating X-rays.

    See the full article here .

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  • richardmitnick 8:27 am on April 25, 2017 Permalink | Reply
    Tags: ALMA Residencia, , Handover   

    From ALMA via ESO: “ALMA Residencia Handed Over” 

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

    ESO

    25 April 2017
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    rhook@eso.org

    1
    The new ALMA Residencia at the ALMA Operations Support Facility has just been handed over to the Joint ALMA Observatory. The celebration event was attended by the ALMA Board and the directors of the three executives — ESO, NAOJ and NRAO. The architects who designed the building were also present. The ALMA Residencia is the last major construction item to be delivered to the ALMA project by ESO.

    The handover of the ALMA Residencia is a landmark in the development of the Atacama Large Millimeter/submillimeter Array (ALMA). The new building will provide accommodation for ALMA staff and visitors at the ALMA Operations Support Facility (OSF), close to San Pedro de Atacama in northern Chile, just 28 kilometres away from the telescope itself. ESO is providing the Residencia, which is its final major contribution to the ALMA project.

    The design for the building was undertaken by the Finnish architects Kouvo & Partanen and was then adapted to the Chilean market by Rigotti & Simunovic Arquitectos, a Chilean architecture firm. The construction contract for the ALMA Residencia was awarded to the consortium AXIS LyD Construcciones Ltda, consisting of Constructora L y D S.A. and Axis Desarrollos Constructivos S.A. Both are Chilean companies that already had extensive experience in constructing residential buildings in the challenging environment of northern Chile. Construction began officially on 23 February 2015.

    The buildings have been designed so that the shape and colour of the exterior of this major architectural project will blend with the topography, the environment and the landscape of the ALMA site. Given the harsh desert environment, remote location and pattern of shift working (both day and night) for the ALMA staff, the Residencia has been designed to provide a pleasant on-site environment for staff and visitors who come from numerous countries worldwide.

    The Residencia has two main zones: common areas and dormitory areas. The design uses a modular concept so that more accommodation can be added if necessary. For now, there are 120 rooms extending across six buildings. The common areas feature impressive leisure facilities including a library, cafeteria, lounge, spa with gym, swimming pool, sauna and barbecue area. There is also a kitchen and an extensive dining room, with space to accommodate half of the residents in one sitting.

    The OSF, the site of the Residencia, is 2000 metres lower than the telescope itself up on the Chajnantor plateau. ALMA consists of an array of 66 high-precision radio antennas, of 12 metres and 7 metres diameter, working at millimetre and submillimetre wavelengths. The observatory began scientific observations at the end of September 2011 and studies the building blocks of stars, planetary systems, galaxies and life itself, letting astronomers address some of the deepest questions of our cosmic origins.

    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.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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  • richardmitnick 8:08 am on April 25, 2017 Permalink | Reply
    Tags: , ,   

    From SLAC: “Machine Learning Dramatically Streamlines Search for More Efficient Chemical Reactions” 


    SLAC Lab

    April 24, 2017
    Glennda Chui

    1
    A diagram shows the many possible paths one simple catalytic reaction can theoretically take – in this case, conversion of syngas, which is a combination of carbon dioxide (CO2) and carbon monoxide (CO), to acetaldehyde. Machine learning allowed SUNCAT theorists to prune away the least likely paths and identify the most likely one (red) so scientists can focus on making it more efficient. (Zachary Ulissi/SUNCAT)

    Even a simple chemical reaction can be surprisingly complicated. That’s especially true for reactions involving catalysts, which speed up the chemistry that makes fuel, fertilizer and other industrial goods. In theory, a catalytic reaction may follow thousands of possible paths, and it can take years to identify which one it actually takes so scientists can tweak it and make it more efficient.

    Now researchers at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have taken a big step toward cutting through this thicket of possibilities. They used machine learning – a form of artificial intelligence – to prune away the least likely reaction paths, so they can concentrate their analysis on the few that remain and save a lot of time and effort.

    The method will work for a wide variety of complex chemical reactions and should dramatically speed the development of new catalysts, the team reported in Nature Communications.

    ‘A Daunting Task’

    “Designing a novel catalyst to speed a chemical reaction is a very daunting task,” said Thomas Bligaard, a staff scientist at the SUNCAT Center for Interface Science and Catalysis, a joint SLAC/Stanford institute where the research took place. “There’s a huge amount of experimental work that normally goes into it.”

    For instance, he said, finding a catalyst that turns nitrogen from the air into ammonia – considered one of the most important developments of the 20th century because it made the large-scale production of fertilizer possible, helping to launch the Green Revolution – took decades of testing various reactions one by one.

    Even today, with the help of supercomputer simulations that predict the results of reactions by applying theoretical models to huge databases on the behavior of chemicals and catalysts, the search can take years, because until now it has relied largely on human intuition to pick possible winners out of the many available reaction paths.

    “We need to know what the reaction is, and what are the most difficult steps along the reaction path, in order to even think about making a better catalyst,” said Jens Nørskov, a professor at SLAC and Stanford and director of SUNCAT.

    “We also need to know whether the reaction makes only the product we want or if it also makes undesirable byproducts. We’ve basically been making reasonable assumptions about these things, and we really need a systematic theory to guide us.”

    Trading Human Intuition for Machine Learning

    For this study, the team looked at a reaction that turns syngas, a combination of carbon monoxide and hydrogen, into fuels and industrial chemicals. The syngas flows over the surface of a rhodium catalyst, which like all catalysts is not consumed in the process and can be used over and over. This triggers chemical reactions that can produce a number of possible end products, such as ethanol, methane or acetaldehyde.

    “In this case there are thousands of possible reaction pathways – an infinite number, really – with hundreds of intermediate steps,” said Zachary Ulissi, a postdoctoral researcher at SUNCAT. “Usually what would happen is that a graduate student or postdoctoral researcher would go through them one at a time, using their intuition to pick what they think are the most likely paths. This can take years.”

    The new method ditches intuition in favor of machine learning, where a computer uses a set of problem-solving rules to learn patterns from large amounts of data and then predict similar patterns in new data. It’s a behind-the-scenes tool in an increasing number of technologies, from self-driving cars to fraud detection and online purchase recommendations.

    Rapid Weeding

    The data used in this process came from past studies of chemicals and their properties, including calculations that predict the bond energies between atoms based on principles of quantum mechanics. The researchers were especially interested in two factors that determine how easily a catalytic reaction proceeds: How strongly the reacting chemicals bond to the surface of the catalyst and which steps in the reaction present the most significant barriers to going forward. These are known as rate-limiting steps.

    A reaction will seek out the path that takes the least energy, Ulissi explained, much like a highway designer will choose a route between mountains rather than waste time looking for an efficient way to go over the top of a peak. With machine learning the researchers were able to analyze the reaction pathways over and over, each time eliminating the least likely paths and fine-tuning the search strategy for the next round.

    Once everything was set up, Ulissi said, “It only took seconds or minutes to weed out the paths that were not interesting. In the end there were only about 10 reaction barriers that were important.” The new method, he said, has the potential to reduce the time needed to identify a reaction pathway from years to months.

    Andrew Medford, a former SUNCAT graduate student who is now an assistant professor at the Georgia Institute of Technology, also contributed to this research, which was funded by the DOE Office of Science.

    See the full article here .

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 7:51 am on April 25, 2017 Permalink | Reply
    Tags: , , , Rock Avalanches   

    From Eos: “What Causes Rock Avalanches?” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    4.24.17
    Terri Cook

    1
    A giant rock avalanche preserved in the Nyainqentanglha Mountains of the Tibetan Plateau, China. Researchers use soil sampled from the avalanche to assess the mechanics behind the frictional weakening of the soil and its implications for the hypermobilty of rock avalanches. Credit: Yufeng Wang.

    Rock avalanches, sudden rock slope failures characterized by very rapid velocities, long runouts, and large volumes, pose some of the most dangerous and expensive geological hazards in mountainous regions. Although numerous mechanisms, including air pockets, fine powder along their base, and elevated pore fluid pressure, have been proposed to explain rock avalanches’ distinctive characteristics, the specific reasons for their “hypermobility” are still vigorously debated by scientists.

    To improve our understanding of what causes these disasters, Wang et al. conducted a series of laboratory tests to examine the weakening mechanisms that contributed to the high-speed motion of the Yigong rock avalanche on the Tibetan Plateau in 2000. This event dislodged 110 million cubic meters of material, which traveled more than 10 kilometers in 10 minutes before reaching and damming the Yigong River. Two months later, when the river finally broke through the avalanche debris, it unleashed a devastating flood that killed 94 people and destroyed the homes of more than 2 million citizens.

    Using a shear rotary apparatus, which rapidly rotates ring-shaped samples to simulate motion along a fault, the team varied the rate at which they applied shear stress to samples of soil obtained from the base of the Yigong rock avalanche and then analyzed each deformed sample’s features. The results indicate that elevated temperatures caused by frictional heating weakened the Yigong basal soil through the combined effects of two mechanisms: moisture fluidization, which both lubricates the sample and reduces the adhesion between its fine particles, and thermal pressurization, which causes friction-heated water to expand, further weakening the fault zone.

    Although the generation of nanoparticles from particle fragmentation may also facilitate soil weakening, this mechanism did not play a key role in generating the Yigong rock avalanche, the team reports. The results have implications for researchers in many geologic disciplines, including landslide dynamics, earthquake mechanics, and risk assessment. (Journal Geophysical Research: Solid Earth, https://doi.org/10.1002/2016JB013624, 2017)

    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 7:32 am on April 25, 2017 Permalink | Reply
    Tags: , , , Heliosphere, Heliotail, ,   

    From Goddard: “NASA’s Cassini, Voyager Missions Suggest New Picture of Sun’s Interaction with Galaxy” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    April 24, 2017
    Sarah Frazier
    sarah.frazier@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    New data from NASA’s Cassini mission, combined with measurements from the two Voyager spacecraft and NASA’s Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun — calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.

    NASA/Voyager 1

    NASA/ESA/ASI Cassini Spacecraft

    NASA/IBEX

    The sun releases a constant outflow of magnetic solar material — called the solar wind — that fills the inner solar system, reaching far past the orbit of Neptune. This solar wind creates a bubble, some 23 billion miles across, called the heliosphere. Our entire solar system, including the heliosphere, moves through interstellar space. The prevalent picture of the heliosphere was one of comet-shaped structure, with a rounded head and an extended tail. But new data covering an entire 11-year solar activity cycle show that may not be the case: the heliosphere may be rounded on both ends, making its shape almost spherical. A paper on these results was published in Nature Astronomy on April 24, 2017.

    “Instead of a prolonged, comet-like tail, this rough bubble-shape of the heliosphere is due to the strong interstellar magnetic field — much stronger than what was anticipated in the past — combined with the fact that the ratio between particle pressure and magnetic pressure inside the heliosheath is high,” said Kostas Dialynas, a space scientist at the Academy of Athens in Greece and lead author on the study.

    1
    New data from NASA’s Cassini, Voyager and Interstellar Boundary Explorer missions show that the heliosphere — the bubble of the sun’s magnetic influence that surrounds the inner solar system — may be much more compact and rounded than previously thought. The image on the left shows a compact model of the heliosphere, supported by this latest data, while the image on the right shows an alternate model with an extended tail. The main difference is the new model’s lack of a trailing, comet-like tail on one side of the heliosphere. This tail is shown in the old model in light blue.
    Credits: Dialynas, et al. (left); NASA (right)

    An instrument on Cassini, which has been exploring the Saturn system over a decade, has given scientists crucial new clues about the shape of the heliosphere’s trailing end, often called the heliotail. When charged particles from the inner solar system reach the boundary of the heliosphere, they sometimes undergo a series of charge exchanges with neutral gas atoms from the interstellar medium, dropping and regaining electrons as they travel through this vast boundary region. Some of these particles are pinged back in toward the inner solar system as fast-moving neutral atoms, which can be measured by Cassini.

    “The Cassini instrument was designed to image the ions that are trapped in the magnetosphere of Saturn,” said Tom Krimigis, an instrument lead on NASA’s Voyager and Cassini missions based at Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, and an author on the study. “We never thought that we would see what we’re seeing and be able to image the boundaries of the heliosphere.”

    2
    Many other stars show tails that trail behind them like a comet’s tail, supporting the idea that our solar system has one too. However, new evidence from NASA’s Cassini, Voyager and Interstellar Boundary Explorer missions suggest that the trailing end of our solar system may not be stretched out in a long tail. From top left and going counter clockwise, the stars shown are LLOrionis, BZ Cam and Mira. Credits: NASA/HST/R.Casalegno/GALEX

    Because these particles move at a small fraction of the speed of light, their journeys from the sun to the edge of the heliosphere and back again take years. So when the number of particles coming from the sun changes — usually as a result of its 11-year activity cycle — it takes years before that’s reflected in the amount of neutral atoms shooting back into the solar system.

    Cassini’s new measurements of these neutral atoms revealed something unexpected — the particles coming from the tail of the heliosphere reflect the changes in the solar cycle almost exactly as fast as those coming from the nose of the heliosphere.

    “If the heliosphere’s ‘tail’ is stretched out like a comet, we’d expect that the patterns of the solar cycle would show up much later in the measured neutral atoms,” said Krimigis.

    3
    5
    4
    The heliosphere is the bubble-like region of space dominated by the Sun, which extends far beyond the orbit of Pluto. Plasma “blown” out from the Sun, known as the solar wind, creates and maintains this bubble against the outside pressure of the interstellar medium, the hydrogen and helium gas that permeates the Milky Way Galaxy. The solar wind flows outward from the Sun until encountering the termination shock, where motion slows abruptly. The Voyager spacecraft have actively explored the outer reaches of the heliosphere, passing through the shock and entering the heliosheath, a transitional region which is in turn bounded by the outermost edge of the heliosphere, called the heliopause. The overall shape of the heliosphere is controlled by the interstellar medium through which it is traveling, as well as the Sun, and is not perfectly spherical.[1] The limited data available and unexplored nature[2] of these structures have resulted in many theories.
    Wikipedia.

    But because patterns from solar activity show just as quickly in tail particles as those from the nose, that implies the tail is about the same distance from us as the nose. This means that long, comet-like tail that scientists envisioned may not exist at all — instead, the heliosphere may be nearly round and symmetrical.

    A rounded heliosphere could come from a combination of factors. Data from Voyager 1 show that the interstellar magnetic field beyond the heliosphere is stronger than scientists previously thought, meaning it could interact with the solar wind at the edges of the heliosphere and compact the heliosphere’s tail.

    The structure of the heliosphere plays a big role in how particles from interstellar space — called cosmic rays — reach the inner solar system, where Earth and the other planets are.

    “This data that Voyager 1 and 2, Cassini and IBEX provide to the scientific community is a windfall for studying the far reaches of the solar wind,” said Arik Posner, Voyager and IBEX program scientist at NASA Headquarters in Washington, D.C., who was not involved with this study.

    “As we continue to gather data from the edges of the heliosphere, this data will help us better understand the interstellar boundary that helps shield the Earth environment from harmful cosmic rays.”

    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

     
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