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  • richardmitnick 3:07 pm on January 14, 2017 Permalink | Reply
    Tags: , , , Caltech, , EurekaAlert, Keck Cosmic Web Imager   

    From Caltech via EurekaAlert: “New Caltech instrument poised to image the cosmic web” 

    Caltech Logo
    Caltech

    1

    EurekaAlert

    12-Jan-2017
    Whitney Clavin
    wclavin@caltech.edu
    626-395-1856

    Keck Cosmic Web Imager ships from Caltech to Keck Observatory

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    Hector Rodriguez, senior mechanical technician, works on the Keck Cosmic Web Imager in a clean room at Caltech. Caltech

    An instrument designed to image the vast web of gas that connects galaxies in the universe has been shipped from Los Angeles to Hawaii, where it will be integrated into the W. M. Keck Observatory.

    Keck Observatory, Mauna Kea, Hawaii, USA
    Keck Observatory, Mauna Kea, Hawaii, USA

    The instrument, called the Keck Cosmic Web Imager, or KCWI, was designed and built by a team at Caltech led by Professor of Physics Christopher Martin. It will be one of the best instruments in the world for taking spectral images of cosmic objects–detailed images where each pixel can be viewed in all wavelengths of visible light. Such high-resolution spectral information will enable astronomers to study the compositions, velocities, and masses of many objects, such as stars and galaxies, in ways that were not possible before.

    One of KCWI’s main goals, and a passion of Martin’s for the past 30 years, is to answer the question: What is the gas around galaxies doing?

    “For decades, astronomers have demonstrated that galaxies evolve. Now we’re trying to figure out how and why,” says Martin. “We know the gas around galaxies is ultimately fueling them, but it is so faint–we still haven’t been able to get a close look at it and understand how this process works.”

    Martin and his team study what is called the cosmic web–a vast network of streams of gas between galaxies. Recently, the scientists have found evidence supporting what is called the cold flow model, in which this gas funnels into the cores of galaxies, where it condenses and forms new stars.

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    The forming galaxy with binary quasars as it fits into the timeline of the Universe. We’re seeing it 10 billion years ago, during the epoch of galaxy formation. Credit: Caltech Academic Media Technologies

    Researchers had predicted that the gas filaments would first flow into a large ring-like structure around the galaxy before spiraling into it–exactly what Martin and his team found using the Palomar Cosmic Web Imager, a precursor to KCWI, at Caltech’s Palomar Observatory near San Diego.

    Caltech Palomar Cosmic Web Imager
    Caltech Palomar Cosmic Web Imager

    “We measured the kinematics, or motion, of the gas around a galaxy and found a very large rotating disk connected to a gas filament,” says Martin. “It was the smoking gun for the cold flow model.”

    With KCWI, the researchers will get a closer look at the gas filaments and ring-like structures around galaxies that range from 10 to 12 billion light-years away, an era when our universe was roughly 2 to 4 billion years old. Not only can KCWI take more detailed pictures than the Palomar Cosmic Web Imager, it has other advances such as better mirror coatings. The combination of these improvements with the fact that KCWI is being installed at one of the twin 10-meter Keck telescopes–the world’s largest observatory with some of the darkest known skies on Earth–means that KCWI will have an improved performance by more than an order of magnitude over the Palomar Cosmic Web Imager.

    KCWI will map the gas flowing from the intergalactic medium–the space between galaxies–into many young galaxies, revealing, for the first time, the dominant mode of galaxy formation in the early universe. The instrument will also search for supergalactic winds from galaxies that drive gas back into the intergalactic medium. How gas flows into and out of forming galaxies is the central open question in the formation of cosmic structures.

    “We designed KCWI to study very dim and diffuse objects, our main emphasis being on the wispy cosmic web and the interactions of galaxies with their surroundings,” says Mateusz (Matt) Matuszewski, the instrument scientist for the project.

    KCWI is also designed to be more a general-purpose instrument than the Palomar’s Cosmic Web Imager, which is mainly for studies of the cosmic web. It will study everything from gas jets around young stars to the winds of dead stars and supermassive black holes and more. “The instrument is really versatile,” says Matuszewski. “Observers can configure the optics to adjust the spatial and spectral scales and resolutions to suit their interests.”

    The nuts and bolts of KCWI

    Scientists and engineers have been busy assembling the highly complex elements of the KCWI instrument at Caltech since 2012. The instrument is about the size of an ice cream truck and weighs over 4,000 kilograms. The core feature of KCWI is its ability to capture spectral information about objects, such as galaxies, across a wide image. Typically, astronomers capture spectra using instruments called spectrographs, which have narrow slit-shaped windows. The spectrograph breaks apart light from the slit into each of the colors making up the target object, just like a prism that spreads light into a rainbow. But traditional spectrographs cannot be used to capture spectral information across an entire image.

    “Traditional spectrographs use multiple small slits to capture many stars or the cores of many galaxies,” says Martin. “Now, we want to look at features that are extended across the sky, such as stellar jets and galaxies, which have complex structures, velocities, and gas flows. If you can only look through a slit, you can only see a small part of what is going on. But we want to see the whole picture. That’s why we need an imaging spectrograph, a device that gives you an image for every single wavelength across a wide view.”

    To create a spectrograph that can image more extended objects like galaxies, KCWI uses what is called an integral field design, which basically divides an image up into 24 slits, and gathers all the spectral information at once.

    “If you’re looking at something big in the sky, it’s inefficient to just have one slit and step your way across that object, so an integral field spectrograph combines a number of slit-shaped mirrors together across a continuous field of view,” says Patrick Morrissey, the project scientist for KCWI who now works at JPL. “Imagine looking into a broken mirror–the reflected image is shifted around depending on the angles of the pieces. This is how the integral field spectrograph works. A series of mirrors works together to make a square-shaped stack of slits across an image appear as a single traditional vertical slit.”

    KCWI has the highest spectral resolution of any integral field spectrograph, which means it can better break apart the rainbow of light to see more colors, or wavelengths. The first phase of the instrument, now on its way to Keck, covers the blue side of the visible spectrum, spanning wavelength ranges from 3500 to 5600 Angstroms. A second phase, extending coverage to the red side of the spectrum, out to 10400 Angstroms, will be built next.

    KCWI to Climb Mauna Kea

    After KCWI arrives in Hawaii on January 18, engineers will guide it up to the top of Mauna Kea, where Keck is perched. A series of checkout and alignment tests is planned, and will be followed in a few months by the first observations through the Keck telescope.

    “There are train tracks around the telescope where the instruments are installed,” says Morrissey. “It’s like one of those old railroad roundhouses where the train would come in and they would spin it to an available space for storage. The telescope turns around, points to the instrument that the astronomer wants to use, and then they roll that instrument on. Soon KCWI will becomes part of the telescope.”

    KCWI is funded by the National Science Foundation, through the Association of Universities for Research in Astronomy (AURA) program, and by the Heising-Simons Foundation, the W.M. Keck Foundation, the Caltech Division of Physics, Mathematics and Astronomy, and the Caltech Optical Observatories.

    See the full article here .

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    Caltech campus
    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

     
  • richardmitnick 12:56 pm on January 12, 2017 Permalink | Reply
    Tags: , Caltech, IC 3639, Monster black holes, , , NGC 1448, , Type Ia supernova, Type II supernova   

    From Space Science Laboratory at UC Berkeley: “NuSTAR – Black Holes Hide in our Cosmic Backyard” 

    UC Berkeley

    UC Berkeley

    SSL UC Berkeley

    Space Science Laboratory

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    No image caption. No image credit.

    NASA/NuSTAR

    NuSTAR

    January 12, 2017
    Christopher Scholz

    Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. But they give themselves away when material they feed on emits high-energy X-rays that NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission can detect. That’s how NuSTAR recently identified two gas-enshrouded supermassive black holes, located at the centers of nearby galaxies.

    “These black holes are relatively close to the Milky Way, but they have remained hidden from us until now,” said Ady Annuar, a graduate student at Durham University in the United Kingdom, who presented the results at the American Astronomical Society meeting in Grapevine, Texas. “They’re like monsters hiding under your bed.”

    Both of these black holes are the central engines of what astronomers call “active galactic nuclei,” a class of extremely bright objects that includes quasars and blazars. Depending on how these galactic nuclei are oriented and what sort of material surrounds them, they appear very different when examined with telescopes.

    Active galactic nuclei are so bright because particles in the regions around the black hole get very hot and emit radiation across the full electromagnetic spectrum — from low-energy radio waves to high-energy X-rays. However, most active nuclei are believed to be surrounded by a doughnut-shaped region of thick gas and dust that obscures the central regions from certain lines of sight. Both of the active galactic nuclei that NuSTAR recently studied appear to be oriented such that astronomers view them edge-on. That means that instead of seeing the bright central regions, our telescopes primarily see the reflected X-rays from the doughnut-shaped obscuring material.

    “Just as we can’t see the sun on a cloudy day, we can’t directly see how bright these active galactic nuclei really are because of all of the gas and dust surrounding the central engine,” said Peter Boorman, a graduate student at the University of Southampton in the United Kingdom.

    Boorman led the study of an active galaxy called IC 3639, which is 170 million light years away.

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    IC 3639, a galaxy with an active galactic nucleus, is seen in this image combining data from the Hubble Space Telescope and the European Southern Observatory.

    This galaxy contains an example of a supermassive black hole hidden by gas and dust. Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA’s Chandra X-Ray Observatory and the Japanese-led Suzaku satellite.

    NASA/Chandra Telescope
    NASA/Chandra Telescope

    JAXA/Suzaku satellite
    JAXA/Suzaku satellite

    The findings from NuSTAR, which is more sensitive to higher energy X-rays than these observatories, confirm the nature of IC 3639 as an active galactic nucleus that is heavily obscured, and intrinsically much brighter than observed.

    Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA’s Chandra X-Ray Observatory and the Japan-led Suzaku satellite. NuSTAR also provided the first precise measurement of how much material is obscuring the central engine of IC 3639, allowing researchers to determine how luminous this hidden monster really is.

    More surprising is the spiral galaxy that Annuar focused on: NGC 1448.

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    NGC 1448 (also designated NGC 1457 and ESO 249-16) is a spiral galaxy located about 60 million light-years away in the constellation Horologium. It has a prominent disk of young and very bright stars surrounding its small, shining core. The galaxy is receding from us with 1168 kilometers per second.

    NGC 1448 has recently been a prolific factory of supernovae, the dramatic explosions that mark the death of stars: after a first one observed in this galaxy in 1983 (SN 1983S), two more have been discovered during the past decade.

    Visible as a red dot inside the disc, in the upper right part of the image, is the supernova observed in 2003 (Type II supernova SN 2003hn), whereas another one, detected in 2001 (Type Ia supernova SN 2001el), can be noticed as a tiny blue dot in the central part of the image, just below the galaxy’s core. If captured at the peak of the explosion, a supernova might be as bright as the whole galaxy that hosts it.

    A Type Ia supernova is a result from the violent explosion of a white dwarf star. This category of supernovae produces consistent peak luminosity. The stability of this luminosity allows these supernovae to be used as standard candles to measure the distance to their host galaxies because the visual magnitude of the supernovae depends primarily on the distance.

    A Type II supernova results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, and no more than 40–50 times the mass of the Sun for this type of explosion. It is distinguished from other types of supernova by the presence of hydrogen in its spectrum. Type II supernovae are mainly observed in the spiral arms of galaxies and in H II regions, but not in elliptical galaxies.

    This image was obtained using the 8.2-metre telescopes of ESO’s Very Large Telescope. It combines exposures taken between July 2002 and the end of November 2003.

    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level
    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    Credit: ESO

    The black hole in its center was only discovered in 2009, even though it is at the center of one of the nearest large galaxies to our Milky Way. By “near,” astronomers mean NGC 1448 is only 38 million light years away (one light year is about 6 trillion miles).

    Annuar’s study discovered that this galaxy also has a thick column of gas hiding the central black hole, which could be part of a doughnut-shaped region. X-ray emission from NGC 1448, as seen by NuSTAR and Chandra, suggests for the first time that, as with IC 3639, there must be a thick layer of gas and dust hiding the active black hole in this galaxy from our line of sight.

    Researchers also found that NGC 1448 has a large population of young (just 5 million year old) stars, suggesting that the galaxy produces new stars at the same time that its black hole feeds on gas and dust. Researchers used the European Southern Observatory New Technology Telescope to image NGC 1448 at optical wavelengths, and identified where exactly in the galaxy the black hole should be. A black hole’s location can be hard to pinpoint because the centers of galaxies are crowded with stars. Large optical and radio telescopes can help detect light from around black holes so that astronomers can find their location and piece together the story of their growth.

    “It is exciting to use the power of NuSTAR to get important, unique information on these beasts, even in our cosmic backyard where they can be studied in detail,” said Daniel Stern, NuSTAR project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California.

    NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

    See the full article here .

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  • richardmitnick 9:50 am on January 12, 2017 Permalink | Reply
    Tags: , Auroral Displays at Brown Dwarfs, , , Caltech   

    From astrobites: “Auroral Displays at Brown Dwarfs” 

    Astrobites bloc

    Astrobites

    Title: Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence
    Authors: G.Hallinan, S. P. Littlefair, G. Cotter, et al.
    First Author’s Institution: California Institute of Technology
    Caltech Logo
    Status: Published in Nature (2015), open access

    Auroras are the spectacular light shows visible in the polar regions at Earth and other planets. In 2015 they were detected for the first time outside of the solar system. Brown dwarfs are objects often described as “failed stars”, meaning they are insufficiently massive to ignite hydrogen fusion in their cores. Today’s paper reports on the remarkable discovery that a particular brown dwarf plays host to auroral displays far more powerful than those found anywhere in the solar system.

    Brown dwarfs

    Artist's concept of a Brown dwarf [not quite a] star. NASA/JPL-Caltech
    Artist’s concept of a Brown dwarf [not quite a] star. NASA/JPL-Caltech

    Brown dwarfs occupy the region between giant planets and the lowest mass stars. It is generally accepted that they form in a manner similar to stars, i.e. the gravitational collapse of interstellar gas, but never reaching a mass sufficient to sustain hydrogen fusion in the core. As such, brown dwarfs are extremely cool, faint objects, making their detection much more difficult than ordinary stars. However, they provide an excellent opportunity to for us to better understand the physics that differentiates the stellar and planetary domains. Since their discovery many surveys have been performed which have revealed, amongst other things, the existence of complex weather systems and strong global magnetic fields.

    Auroras

    Understanding the interaction of the magnetic field at a brown dwarf with its nearby space environment is a key scientific goal. At Earth, space scientists observe the aurora as a means of revealing the structure and dynamics of the magnetic field, and the plasma which interacts with it. Before turning to auroras at brown dwarfs we shall briefly review at what we know about auroras from our studies at Earth and other solar system planets.

    The vibrant displays that we see are a result of charged particles (i.e. electrons and ions) from the plasma population around the Earth raining down along magnetic field lines, and colliding with molecules in the atmosphere. These collisions excite the atmospheric constituents to a higher energy state, causing the emission of a photon as they return to their original state.

    Auroral emissions aren’t just confined to Earth; they are found at other magnetised planets in the solar system, with Jupiter being a particularly spectacular example.

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    JUNE 30, 2016: Astronomers are using NASA’s Hubble Space Telescope to study auroras — stunning light shows in a planet’s atmosphere — on the poles of the largest planet in the solar system, Jupiter. The auroras were photographed during a series of Hubble Space Telescope Imaging Spectrograph far-ultraviolet-light observations taking place as NASA’s Juno spacecraft approaches and enters into orbit around Jupiter. The aim of the program is to determine how Jupiter’s auroras respond to changing conditions in the solar wind, a stream of charged particles emitted from the sun. Auroras are formed when charged particles in the space surrounding the planet are accelerated to high energies along the planet’s magnetic field. When the particles hit the atmosphere near the magnetic poles, they cause it to glow like gases in a fluorescent light fixture. Jupiter’s magnetosphere is 20,000 times stronger than Earth’s. These observations will reveal how the solar system’s largest and most powerful magnetosphere behaves. The full-color disk of Jupiter in this image was separately photographed at a different time by Hubble’s Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project that annually captures global maps of the outer planets.
    Date 30 June 2016
    Source http://hubblesite.org/newscenter/archive/releases/2016/24
    Author NASA, ESA, and J. Nichols (University of Leicester)

    Neither are they confined only to the visible part of the spectrum; auroral emissions occur from radio frequencies through to UV and X-ray.

    Now we return to brown dwarfs. Since 2006 it has been known that a handful of brown dwarfs emit very regular and persistent radio bursts. These burst are pulsed at the rotation period of the dwarf, leading some researchers to suggest that they may be caused by auroras that are generated in a similar manner to Jupiter’s main auroral oval. The pulsing in this case may be due to the magnetic axis being tilted from the spin axis, so that as the dwarf rotates the auroral emission cones into our line of sight. This motivated the authors of today’s paper to target a particular brown dwarf, LSR J1835 + 3259, with simultaneous radio and optical observation, pursuing a possible relation between the two.

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    LSR J1835 + 3259. Image: http://images.zeit.de/ http://www.theweeklyobserver.com/ailed-star-shows-dazzling-display-of-northern-lights/5575/

    Radio observations were made using the Very Large Array (VLA) radio telescope, while simultaneously, optical measurements were made with the 5.1 m Hale telescope at the Palomar Observatory with follow-up observations from the 10 m Keck telescope.

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

    Caltech Palomar 200 inch Hale Telescope, at Mt Wilson, CA, USA
    Caltech Hale Telescope at Palomar interior
    Caltech Palomar 200 inch Hale Telescope, at Mt Wilson, CA, USA

    Keck Observatory, Mauna Kea, Hawaii, USA
    Keck Observatory Interior
    Keck Observatory, Mauna Kea, Hawaii, USA

    The results of the observations are shown in Figure 1, where the light curve from the optical measurements (Fig 1a) shows a clear periodicity of 2.84 h. Observations of the radio emission (Fig 1b) show the same periodicity, with a slight offset in phase causing it to lag slightly behind the optical emission. The authors attribute their findings to auroras which are driven by strong electric currents flowing in the magnetosphere of the dwarf.

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    Figure 1: (a) Optical measurements of Balmer line emission of LSR J1835 made using the Hale telescope. (b) Corresponding radio observations of the same object made using the VLA radio telescope. [Figure 1 from Hallinan et al. 2015]

    With this discovery many open questions are presented. What is the mechanism driving the auroras? It may be interaction with the interstellar medium, analogous to the process of the Earth’s magnetosphere interacting with the solar wind. Or it could be due to a continuously replenishing source of plasma mass outflow from within a closed magnetosphere, analogous to the mechanism producing Jupiter’s main auroral oval. Additionally, the source of the required plasma population is unknown, with the cool temperatures (∼2000 K) of brown dwarfs being unable to support significant ionisation of their atmospheres, and the lack of nearby stars restricting the possibility ionisation by stellar irradiation.

    Ultimately it is an exciting prospect that this discovery, along with the arrival of even more sensitive radio telescopes (e.g. the Square Kilometre Array), may pave the way towards detecting auroras at exoplanets.

    SKA Square Kilometer Array

    This which would add a novel technique to the exoplanet-detectors toolkit, and enable us to learn about the magnetic fields and plasma populations around those objects.

    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 9:34 pm on December 23, 2016 Permalink | Reply
    Tags: Aquaporin, Caltech, ,   

    From Caltech: “Visualizing Gene Expression with MRI” 

    Caltech Logo
    Caltech

    12/23/2016

    Lori Dajose
    (626) 395-1217
    ldajose@caltech.edu

    1
    An illustration of aquaporin’s effect on cells. Credit: M. Shapiro Laboratory/Caltech

    Genes tell cells what to do—for example, when to repair DNA mistakes or when to die—and can be turned on or off like a light switch. Knowing which genes are switched on, or expressed, is important for the treatment and monitoring of disease. Now, for the first time, Caltech scientists have developed a simple way to visualize gene expression in cells deep inside the body using a common imaging technology.

    Researchers in the laboratory of Mikhail Shapiro, assistant professor of chemical engineering and Heritage Medical Research Institute Investigator, have invented a new method to link magnetic resonance imaging (MRI) signals to gene expression in cells—including tumor cells—in living tissues. The technique, which eventually could be used in humans, would allow gene expression to be monitored non-invasively, requiring no surgical procedures such as biopsies.

    The work appears in the December 23 online edition of the journal Nature Communications.

    In MRI, hydrogen atoms in the body—atoms that are mostly contained in water molecules and fat—are excited using a magnetic field. The excited atoms, in turn, emit signals that can be used to create images of the brain, muscle, and other tissues, which can be distinguished based on the local physical and chemical environment of the water molecules. While this technique is widely used, it usually provides only anatomical snapshots of tissues or physiological functions such as blood flow rather than observations of the activity of specific cells.

    “We thought that if we could link signals from water molecules to the expression of genes of interest, we could change the way the cell looks under MRI,” says Arnab Mukherjee, a postdoctoral scholar in chemical engineering at Caltech and co-lead author on the paper.

    The group turned to a protein that naturally occurs in humans, called aquaporin. Aquaporin sits within the membrane that envelops cells and acts as a gatekeeper for water molecules, allowing them to move in and out of the cell. Shapiro’s team realized that increasing the number of aquaporins on a given cell made it stand out in MRI images acquired using a common clinical technique called diffusion-weighted imaging, which is sensitive to the movement of water molecules. They then linked aquaporin to genes of interest, making it what scientists call a reporter gene. This means that when a gene of interest is turned on, the cell will overexpress aquaporin, making the cell look darker under diffusion-weighted MRI.

    The researchers showed that this technique was successful in monitoring gene expression in a brain tumor in mice. After implanting the tumor, they gave the mice a drug to trigger the tumor cells to express the aquaporin reporter gene, which made the tumor look darker in MRI images.

    “Overexpression of aquaporin has no negative impact on cells because it is exclusive to water and simply allows the molecules to go back and forth across the cell membrane,” Shapiro says. Under normal physiological conditions the number of water molecules entering and exiting an aquaporin-expressing cell is the same, so that the total amount of water in each cell does not change. “Aquaporin is a very convenient way to genetically change the way that cells look under MRI.”

    Though the work was done in mice, it has the potential for clinical translation, according to Shapiro. Aquaporin is a naturally occurring gene and will not cause an immune reaction. Previously developed reporter genes for MRI have been much more limited in their capabilities, requiring the use of specific metals that are not always available in some tissues.

    “An effective reporter gene for MRI is a ‘holy grail’ in biomedical imaging because it would allow cellular function to be observed non-invasively,” says Shapiro. “Aquaporins are a new way to think about this problem. It is remarkable that simply allowing water molecules to more easily get into and out of cells in a tissue gives us the ability to remotely see those cells in the middle of the body.”

    The paper is titled Non-invasive imaging using reporter genes altering cellular water permeability. In addition to Shapiro and Mukherjee, other coauthors include Caltech graduate students Di Wu (MS ’16 and co-lead author) and Hunter Davis. The work was funded by the Dana Foundation, a Burroughs Wellcome Career Award at the Scientific Interface, the Heritage Medical Research Institute, and the National Institutes of Health.

    See the full article here .

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

     
  • richardmitnick 12:14 pm on December 16, 2016 Permalink | Reply
    Tags: , , Caltech, , RIK-210   

    From Caltech via phys.org: “Astronomers observe mysterious dimming of a young nearby star” 

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    Caltech

    phys.org

    phys.org

    December 16, 2016
    Tomasz Nowakowski

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    Flattened and median filtered K2 light curve of RIK-210. The data are phase-wrapped on the dip period of 5.6685 days. A grouping of shallow dips preceding the main dip is prominent for the first four rotation periods of the campaign, then largely disappears. Variability fit B was used to make this figure. Credit: David et al., 2016.

    Astronomers have spotted transient, transit-like dimming events of a young star named RIK-210 located some 472 light years away in the Upper Scorpius OB association. However, what puzzles the scientists is the mystery behind this dimming as it can not be caused by an eclipsing stellar or brown dwarf companion. They describe their search for plausible explanations in a paper published Dec. 12 on the arXiv pre-print server.

    RIK-210 is around five to 10 million years old, about half as massive as the sun and has a radius of approximately 1.24 solar radii. The star has been recently observed by NASA’s prolonged Kepler mission, known as K2, during its Campaign 2, lasting from Aug. 22 to Nov. 11, 2014. A team of researchers led by Trevor David of the California Institute of Technology (Caltech) has analyzed the data provided by K2.

    “We find transient, transit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology,” the scientists wrote in the paper.

    The team found that these dimming events occur approximately every 5.67 days, in phase with the stellar rotation, noting that they are deep (sometimes greater than 15 percent) and short in duration relative to the rotational period. Moreover, the morphology of the dimmings is variable throughout the whole observational campaign, while the starspot modulation pattern remains stable over this period of time.

    While such variable dimmings have been documented around mature stars and stellar remnants, it has not been previously observed around a young star lacking a protoplanetary disk, as in the case of RIK-210.

    In the search for possible explanations of the observed transient, transit-like dimming events, the researchers at first excluded the possibility that they can be caused by an eclipsing stellar or brown dwarf companion. This hypothesis was ruled out as it is inconsistent with radial velocity measurements as well as with archival and follow-up photometry data.

    The researchers emphasized that the dimmings cannot be due to a single spherical body because of the variable morphology of these events. They added that based on the observed depths and durations, it is also unlikely that the dimmings could be explained by features on the stellar surface.

    According to the team, the most plausible explanation of the nature of the obscuring material is that it could be a magnetospheric cloud. They assume that a cloud of plasma analogous to those observed in high-mass stars, or a dusty accretion column, could naturally explain the synchronicity between the rotation period and the dimming events.

    “Since the accretion timescale is … much shorter than the orbital period, this model might explain the variable depths and morphologies of dimming events,” the paper reads.

    Other explanations taken into account by the researchers are: an accretion flow from residual gas and dust, remnants of the late stages of planet formation, the product of a giant-impact type collision, an enshrouded protoplanet with an extended tail, or one or more eccentric bodies undergoing periodic tidal disruption upon each periastron passage.

    In order to finally confirm which of the proposed hypotheses is true, the team calls for continued photometric and spectroscopic monitoring.

    “Multi-band photometric monitoring can be used to test whether the dip depths are wavelength-dependent; solid-body transits are achromatic, while extinction by dust is less severe at redder wavelengths. Finally, spectroscopic monitoring while the star is known to be dimming can test whether there is enhanced absorption by a gaseous cloud transiting the star,” the scientists concluded.

    See the full article here .

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 6:50 pm on December 11, 2016 Permalink | Reply
    Tags: Caltech, , , The right way to simulate the Milky Way   

    From Science Node: “The right way to simulate the Milky Way” 

    Science Node bloc
    Science Node

    13 Sep, 2016 [Where oh where has this been?]
    Whitney Clavin

    Astronomers have created the most detailed computer simulation to date of our Milky Way galaxy’s formation, from its inception billions of years ago as a loose assemblage of matter to its present-day state as a massive, spiral disk of stars.

    The simulation solves a decades-old mystery surrounding the tiny galaxies that swarm around the outside of our much larger Milky Way. Previous simulations predicted that thousands of these satellite, or dwarf, galaxies should exist. However, only about 30 of the small galaxies have ever been observed. Astronomers have been tinkering with the simulations, trying to understand this ‘missing satellites’ problem to no avail.


    Access mp4 video here .
    Supercomputers and superstars. Caltech associate professor of theoretical astrophysics Phil Hopkins and Carnegie-Caltech research fellow Andrew Wetzel use XSEDE supercomputers to build the most detailed and realistic simulation of galaxy formation ever created. The results solve a decades-long mystery regarding dwarf galaxies around our Milky Way. Courtesy Caltech.

    Now, with the new simulation — which used resources from the Extreme Science and Engineering Discovery Environment (XSEDE) running in parallel for 700,000 central processing unit (CPU) hours — astronomers at the California Institute of Technology (Caltech) have created a galaxy that looks like the one we live in today, with the correct, smaller number of dwarf galaxies.

    “That was the aha moment, when I saw that the simulation can finally produce a population of dwarf galaxies like the ones we observe around the Milky Way,” says Andrew Wetzel, postdoctoral fellow at Caltech and Carnegie Observatories in Pasadena, and lead author of a paper about the new research, published August 20 in Astrophysical Journal Letters.

    One of the main updates to the new simulation relates to how supernovae, explosions of massive stars, affect their surrounding environments. In particular, the simulation incorporated detailed formulas that describe the dramatic effects that winds from these explosions can have on star-forming material and dwarf galaxies. These winds, which reach speeds up to thousands of kilometers per second, “can blow gas and stars out of a small galaxy,” says Wetzel.

    Indeed, the new simulation showed the winds can blow apart young dwarf galaxies, preventing them from reaching maturity. Previous simulations that were producing thousands of dwarf galaxies weren’t taking the full effects of supernovae into account.

    “We had thought before that perhaps our understanding of dark matter was incorrect in these simulations, but these new results show we don’t have to tinker with dark matter,” says Wetzel. “When we more precisely model supernovae, we get the right answer.”

    Astronomers simulate our galaxy to understand how the Milky Way, and our solar system within it, came to be. To do this, the researchers tell a computer what our universe was like in the early cosmos. They write complex codes for the basic laws of physics and describe the ingredients of the universe, including everyday matter like hydrogen gas as well as dark matter, which, while invisible, exerts gravitational tugs on other matter. The computers then go to work, playing out all the possible interactions between particles, gas, and stars over billions of years.

    “In a galaxy, you have 100 billion stars, all pulling on each other, not to mention other components we don’t see, like dark matter,” says Caltech’s Phil Hopkins, associate professor of theoretical astrophysics and principal scientist for the new research. “To simulate this, we give a supercomputer equations describing those interactions and then let it crank through those equations repeatedly and see what comes out at the end.”

    The researchers are not done simulating our Milky Way. They plan to use even more computing time, up to 20 million CPU hours, in their next rounds. This should lead to predictions about the very faintest and smallest of dwarf galaxies yet to be discovered. Not a lot of these faint galaxies are expected to exist, but the more advanced simulations should be able to predict how many are left to find.

    The study was funded by Caltech, a Sloan Research Fellowship, the US National Science Foundation (NSF), NASA, an Einstein Postdoctoral Fellowship, the Space Telescope Science Institute, UC San Diego, and the Simons Foundation.

    Other coauthors on the study are: Ji-Hoon Kim of Stanford University, Claude-André Faucher-Giguére of Northwestern University, Dušan Kereš of UC San Diego, and Eliot Quataert of UC Berkeley.

    See the full article here .

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    Science Node is an international weekly online publication that covers distributed computing and the research it enables.

    “We report on all aspects of distributed computing technology, such as grids and clouds. We also regularly feature articles on distributed computing-enabled research in a large variety of disciplines, including physics, biology, sociology, earth sciences, archaeology, medicine, disaster management, crime, and art. (Note that we do not cover stories that are purely about commercial technology.)

    In its current incarnation, Science Node is also an online destination where you can host a profile and blog, and find and disseminate announcements and information about events, deadlines, and jobs. In the near future it will also be a place where you can network with colleagues.

    You can read Science Node via our homepage, RSS, or email. For the complete iSGTW experience, sign up for an account or log in with OpenID and manage your email subscription from your account preferences. If you do not wish to access the website’s features, you can just subscribe to the weekly email.”

     
  • richardmitnick 3:18 pm on December 9, 2016 Permalink | Reply
    Tags: , Biofilms, , Caltech, ,   

    From Caltech: “Protein Disrupts Infectious Biofilms” 

    Caltech Logo

    Caltech

    12/08/2016

    Lori Dajose
    (626) 395-1217
    ldajose@caltech.edu

    Many infectious pathogens are difficult to treat because they develop into biofilms, layers of metabolically active but slowly growing bacteria embedded in a protective layer of slime, which are inherently more resistant to antibiotics. Now, a group of researchers at Caltech and the University of Oxford have made progress in the fight against biofilms. Led by Dianne Newman, the Gordon M. Binder/Amgen Professor of Biology and Geobiology, the group identified a protein that degrades and inhibits biofilms of Pseudomonas aeruginosa, the primary pathogen in cystic fibrosis (CF) infections.

    The work is described in a paper in the journal Science that will appear online December 8.

    1
    Crystal structure of the PodA protein complex with three molecules of 1-hydroxyphenazine, the reaction product, bound in the active sites.
    Credit: Kyle Costa/Caltech

    “Pseudomonas aeruginosa causes chronic infections that are difficult to treat, such as those that inhabit burn wounds, diabetic ulcers, and the lungs of individuals living with cystic fibrosis,” Newman says. “In part, the reason these infections are hard to treat is because P. aeruginosa enters a biofilm mode of growth in these contexts; biofilms tolerate conventional antibiotics much better than other modes of bacterial growth. Our research suggests a new approach to inhibiting P. aeruginosa biofilms.”

    The group targeted pyocyanin, a small molecule produced by P. aeruginosa that produces a blue pigment. Pyocyanin has been used in the clinical identification of this strain for over a century, but several years ago the Newman group demonstrated that the molecule also supports biofilm growth, raising the possibility that its degradation might offer a new route to inhibit biofilm development.

    To identify a factor that would selectively degrade pyocyanin, Kyle Costa, a postdoctoral scholar in biology and biological engineering, turned to a milligram of soil collected in the courtyard of the Beckman Institute on the Caltech campus. From the soil, he isolated another bacterium, Mycobacterium fortuitum, that produces a previously uncharacterized small protein called pyocyanin demethylase (PodA).

    Adding PodA to growing cultures of P. aeruginosa, the team discovered, inhibits biofilm development.

    “While there is precedent for the use of enzymes to treat bacterial infections, the novelty of this study lies in our observation that selectively degrading a small pigment that supports the biofilm lifestyle can inhibit biofilm expansion,” says Costa, the first author on the study. The work, Costa says, is relevant to anyone interested in manipulating microbial biofilms, which are common in natural, clinical, and industrial settings. “There are many more pigment-producing bacteria out there in a wide variety of contexts, and our results pave the way for future studies to explore whether the targeted manipulation of analogous molecules made by different bacteria will have similar effects on other microbial populations.”

    While it will take several years of experimentation to determine whether the laboratory findings can be translated to a clinical context, the work has promise for the utilization of proteins like PodA to treat antibiotic-resistant biofilm infections, the researchers say.

    “What is interesting about this result from an ecological perspective is that a potential new therapeutic approach comes from leveraging reactions catalyzed by soil bacteria,” says Newman. “These organisms likely co-evolved with the pathogen, and we may simply be harnessing strategies other microbes use to keep it in check in nature. The chemical dynamics between microorganisms are fascinating, and we have so much more to learn before we can best exploit them.”

    The paper is titled Pyocyanin degradation by a tautomerizing demethylase inhibits Pseudomonas aeruginosa biofilms. In addition to Costa and Newman, other co-authors include Caltech graduate student Nathaniel Glasser and Professor Stuart Conway of the University of Oxford. The work was funded by the National Institutes of Health’s National Institute of Allergy and Infectious Diseases, the National Science Foundation, the Howard Hughes Medical Institute, the Molecular Observatory at the Beckman Institute at Caltech, the Gordon and Betty Moore Foundation, and the Sanofi-Aventis Bioengineering Research Program at Caltech.

    See the full article here .

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 6:53 am on November 26, 2016 Permalink | Reply
    Tags: A distinct state of matter, , , Caltech, New Clues Emerge in 30-Year-Old Superconductor Mystery, Nonlinear optical rotational anisotropy, Pseudogap,   

    From Caltech: “New Clues Emerge in 30-Year-Old Superconductor Mystery” 

    Caltech Logo

    Caltech

    11/21/2016

    Whitney Clavin
    (626) 395-1856
    wclavin@caltech.edu

    1
    An artistic representation of the data showing the breaking of spatial inversion and rotational symmetries in the pseudogap region of superconducting materials—evidence that the pseudogap is a distinct phase of matter. Rings of light reflected from a superconductor reveal the broken symmetries. Credit: Hsieh Lab/Caltech

    One of the greatest mysteries of experimental physics is how so-called high-temperature superconducting materials work. Despite their name, high-temperature superconductors—materials that carry electrical current with no resistance—operate at chilly temperatures less than minus 135 degrees Celsius. They can be used to make superefficient power cables, medical MRIs, particle accelerators, and other devices. Cracking the mystery of how these materials work could lead to superconducting devices that operate at room temperatures—and could revolutionize electrical devices, including laptops and phones.

    In a new paper in the journal Nature Physics, researchers with the Institute for Quantum Information and Matter at Caltech have at last solved one piece of this enduring puzzle. They have confirmed that a transitional phase of matter called the pseudogap—one that occurs before these materials are cooled down to become superconducting—represents a distinct state of matter, with properties very different from those of the superconducting state itself.

    When matter transitions from one state, or phase, to another—say, water freezing into ice—there is a change in the ordering pattern of the materials’ particles. Physicists previously had detected hints of some type of ordering of electrons inside the pseudogap state. But exactly how they were ordering—and whether that ordering constituted a new state of matter—was unclear until now.

    “A peculiar property of all these high-temperature superconductors is that just before they enter the superconducting state, they invariably first enter the pseudogap state, whose origins are equally if not more mysterious than the superconducting state itself,” says David Hsieh, professor of physics at Caltech and principal investigator of the new research. “We have discovered that in the pseudogap state, electrons form a highly unusual pattern that breaks nearly all of the symmetries of space. This provides a very compelling clue to the actual origin of the pseudogap state and could lead to a new understanding of how high-temperature superconductors work.”

    The phenomenon of superconductivity was first discovered in 1911. When certain materials are chilled to super-cold temperatures, as low as a few degrees above absolute zero (a few degrees Kelvin), they carry electrical current with no resistance, so that no heat or energy is lost. In contrast, our laptops are not made of superconducting materials and therefore experience electrical resistance and heat up.

    Chilling materials to such extremely low temperatures requires liquid helium. However, because liquid helium is rare and expensive, physicists have been searching for materials that can function as superconductors at ever-higher temperatures. The so-called high-temperature superconductors, discovered in 1986, are now known to operate at temperatures up to 138 Kelvin (minus 135 degrees Celsius) and thus can be cooled with liquid nitrogen, which is more affordable than liquid helium. The question that has eluded physicists, however—despite three Nobel Prizes to date awarded in the field of superconductivity—is exactly how high-temperatures superconductors work.

    The dance of superconducting electrons

    Materials become superconducting when electrons overcome their natural repulsion and form pairs. This pairing can occur under extremely cold temperatures, allowing the electrons, and the electrical currents they carry, to move unencumbered. In conventional superconductors, electron pairing is caused by natural vibrations in the crystal lattice of the superconducting material, which act like glue to hold the pairs together.

    But in high-temperature superconductors, this form of “glue” is not strong enough to bind the electron pairs. Researchers think that the pseudogap, and how electrons order themselves in this phase, holds clues about what this glue may constitute for high-temperature superconductors. To study electron ordering in the pseudogap, Hsieh and his team have invented a new laser-based method called nonlinear optical rotational anisotropy. In the method, a laser is pointed at the superconducting material; in this case, crystals of ytttrium barium copper oxide (YBa2Cu3Oy). An analysis of the light reflected back at half the wavelength compared to that going in reveals any symmetry in the arrangement of the electrons in the crystals.

    Broken symmetries point to new phase

    Different phases of matter have distinct symmetries. For example, when water turns into ice, physicists say the symmetry has been “broken.”

    “In water,” Hsieh explains, “the H2O molecules are pretty randomly oriented. If you were swimming in an infinite pool of water, your surroundings look the same no matter where you are. In ice, on the other hand, the H2O molecules form a regular periodic network, so if you imagine yourself submerged in an infinite block of ice, your surroundings appear different depending on whether you are sitting on an H or O atom. Therefore, we say that the translational symmetry of space is broken in going from water to ice.”

    With the new tool, Hsieh’s team was able to show that the electrons cooled to the pseudogap phase broke a specific set of spatial symmetries called inversion and rotational symmetry. “As soon as the system entered the pseudogap region, either as a function of temperature or the amount of oxygen in the compound, there was a loss of inversion and rotational symmetries, clearly indicating a transition into a new phase of matter,” says Liuyan Zhao, a postdoctoral scholar in the Hsieh lab and lead author of the new study. “It is exciting that we are using a new technology to solve an old problem.”

    “The discovery of broken inversion and rotational symmetries in the pseudogap drastically narrows down the set of possibilities for how the electrons are self-organizing in this phase,” says Hsieh. “In some ways, this unusual phase may turn out to be the most interesting aspect of these superconducting materials.”

    The Nature Physics study, entitled A global-inversion-symmetry-broken phase inside the pseudogap region of YBa2Cu3Oy, was funded by the Army Research Office, the National Science Foundation, the Gordon and Betty Moore Foundation, the Canadian Institute for Advanced Research, and the Natural Sciences and Engineering Research Council. Other authors are C. A. Belvin of Wellesley College, Massachusetts; R. Liang, D.A. Bonn, and W.N. Hardy of the University of British Columbia, Vancouver; and N.P. Armitage of The Johns Hopkins University, Baltimore.

    See the full article here .

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 7:52 am on November 5, 2016 Permalink | Reply
    Tags: , Caltech, ,   

    From Caltech: “Realistic Solar Corona Loops Simulated in Lab” 

    Caltech Logo
    Caltech

    11/04/2016

    Robert Perkins
    (626) 395-1862
    rperkins@caltech.edu

    1
    Side-by-side: A real coronal loop (left) compared to one simulated in Paul Bellan’s lab (right).
    Credit: Courtesy of P. Bellan/Caltech

    Caltech applied physicists have experimentally simulated the sun’s magnetic fields to create a realistic coronal loop in a lab.

    Coronal loops are arches of plasma that erupt from the surface of the sun following along magnetic field lines. Because plasma is an ionized gas—that is, a gas of free-flowing electrons and ions—it is an excellent conductor of electricity. As such, solar corona loops are guided and shaped by the sun’s magnetic field.

    The earth’s magnetic field acts as a shield that protects humans from the strong X-rays and energized particles emitted by the eruptions, but communications satellites orbit outside this shield field and therefore remain vulnerable. In March 1989, a particularly large flare unleashed a blast of charged particles that temporarily knocked out one of the National Oceanic and Atmospheric Administration’s geostationary operational environmental satellites that monitor the earth’s weather; caused a sensor problem on the space shuttle Discovery; and tripped circuit breakers on Hydro-Québec’s power grid, which blacked out the province of Quebec in Ontario, Canada, for nine hours.

    “This potential for causing havoc—which only increases the more humanity relies on satellites for communications, weather forecasting, and keeping track of resources—makes understanding how these solar events work critically important,” says Paul Bellan, professor of applied physics in the Division of Engineering and Applied Science.

    Although simulated coronal loops have been created in labs before, this latest attempt incorporated a magnetic strapping field that binds the loop to the sun’s surface. Think of a strapping field like the metal hoops on the outside of a wooden barrel. While the slats of the barrel are continually under pressure pushing outward, the metal hoops sit perpendicularly to the slats and hold the barrel together.

    The strength of this strapping field diminishes with distance from the sun. This means that when close to the solar surface, the loops are clamped down tightly by the strapping field but then can break loose and blast away if they rise to a certain altitude where the strapping field is weaker. These eruptions are known as solar flares and coronal mass ejections (CMEs).

    CMEs are rope-like discharges of hot plasma that accelerate away from the sun’s surface at speeds of more than a million miles per hour. These eruptions are capable of releasing energy equivalent to 1 billion megatons of TNT, making them potentially the most powerful explosions in the solar system. (CMEs are not to be confused with solar flares, which often occur as part of the same event. Solar flares are bursts of light and energy, while CMEs are blasts of particles embedded in a magnetic field.)

    The simulated loops and strapping fields provide new insight into how energy is stored in the solar corona and then released suddenly. Bellan worked with Caltech graduate student Bao Ha (MS ’10, PhD ’16) to create the strapping field and coronal loop. The results of their experiments were published in the journal Geophysical Research Letters on September 17, 2016.

    Bellan and his colleagues have been working on laboratory-scale simulations of solar corona phenomena for two decades. In the lab, the team generates ropes of plasma in a 1.5-meter-long vacuum chamber.

    “Studying coronal mass ejections is challenging, since humans do not know how and when the sun will erupt. But laboratory experiments permit the control of eruption parameters and enable the systematic explorations of eruption dynamics,” says Ha, lead author of the GRL paper. “While experiments with the same eruption parameters are easily reproducible, the loop dynamics vary depending on the configuration of the strapping magnetic field.”

    Simulating a strapping field with strength that fades over the relatively short length of the vacuum chamber proved difficult, Bellan says. In order to make it work, Ha and Bellan had to engineer electromagnetic coils that produce the strapping field inside the chamber itself.

    After more than three years of design, fabrication, and testing, Bellan and Ha were able to create a strapping field that peaks in strength about 10 centimeters away from where the plasma loop forms, then dies off a short distance farther down the vacuum chamber.

    The arrangement allows Bellan and Ha to watch the plasma loop slowly grow in size, then reach a critical point and fire off to the far end of the chamber.

    Next, Bellan plans to measure the magnetic field inside the erupting loop and also study the waves that are emitted when plasmas break apart.

    Their paper, titled Laboratory demonstration of slow rise to fast acceleration of arched magnetic flux ropes, is available online at http://onlinelibrary.wiley.com/doi/10.1002/2016GL069744/full. The research was supported by the National Science Foundation, the Air Force Office of Scientific Research, and the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences.

    See the full article here .

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    Caltech campus
    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

     
  • richardmitnick 3:59 pm on October 19, 2016 Permalink | Reply
    Tags: Caltech, Curious Tilt of the Sun Traced to Undiscovered Planet,   

    From Caltech: “Curious Tilt of the Sun Traced to Undiscovered Planet” 

    Caltech Logo
    Caltech

    10/19/2016

    Robert Perkins
    (626) 395-1862
    rperkins@caltech.edu

    1
    This artistic rendering shows the distant view from Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side. Credit: Caltech/R. Hurt (IPAC).

    Planet Nine—the undiscovered planet at the edge of the Solar System that was predicted by the work of Caltech’s Konstantin Batygin and Mike Brown in January 2016—appears to be responsible for the unusual tilt of the sun, according to a new study.

    The large and distant planet may be adding a wobble to the solar system, giving the appearance that the sun is tilted slightly.

    “Because Planet Nine is so massive and has an orbit tilted compared to the other planets, the solar system has no choice but to slowly twist out of alignment,” says Elizabeth Bailey, a graduate student at Caltech and lead author of a study announcing the discovery.

    All of the planets orbit in a flat plane with respect to the sun, roughly within a couple degrees of each other. That plane, however, rotates at a six-degree tilt with respect to the sun—giving the appearance that the sun itself is cocked off at an angle. Until now, no one had found a compelling explanation to produce such an effect. “It’s such a deep-rooted mystery and so difficult to explain that people just don’t talk about it,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy.

    Brown and Batygin’s discovery of evidence that the sun is orbited by an as-yet-unseen planet—that is about 10 times the size of Earth with an orbit that is about 20 times farther from the sun on average than Neptune’s—changes the physics. Planet Nine, based on their calculations, appears to orbit at about 30 degrees off from the other planets’ orbital plane—in the process, influencing the orbit of a large population of objects in the Kuiper Belt, which is how Brown and Batygin came to suspect a planet existed there in the first place.

    “It continues to amaze us; every time we look carefully we continue to find that Planet Nine explains something about the solar system that had long been a mystery,” says Batygin, an assistant professor of planetary science.

    Their findings have been accepted for publication in an upcoming issue of the Astrophysical Journal, and will be presented on October 18 at the American Astronomical Society’s Division for Planetary Sciences annual meeting, held in Pasadena.

    The tilt of the solar system’s orbital plane has long befuddled astronomers because of the way the planets formed: as a spinning cloud slowly collapsing first into a disk and then into objects orbiting a central star.

    Planet Nine’s angular momentum is having an outsized impact on the solar system based on its location and size. A planet’s angular momentum equals the mass of an object multiplied by its distance from the sun, and corresponds with the force that the planet exerts on the overall system’s spin. Because the other planets in the solar system all exist along a flat plane, their angular momentum works to keep the whole disk spinning smoothly.

    Planet Nine’s unusual orbit, however, adds a multi-billion-year wobble to that system. Mathematically, given the hypothesized size and distance of Planet Nine, a six-degree tilt fits perfectly, Brown says.

    The next question, then, is how did Planet Nine achieve its unusual orbit? Though that remains to be determined, Batygin suggests that the planet may have been ejected from the neighborhood of the gas giants by Jupiter, or perhaps may have been influenced by the gravitational pull of other stellar bodies in the solar system’s extreme past.

    For now, Brown and Batygin continue to work with colleagues throughout the world to search the night sky for signs of Planet Nine along the path they predicted in January. That search, Brown says, may take three years or more.

    See the full article here .

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    Caltech campus
    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

     
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