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  • richardmitnick 7:06 am on February 1, 2018 Permalink | Reply
    Tags: , STORM-stochastic optical reconstruction microscopy, Super-resolution microscopy, UC Berkeley   

    From UC Berkeley: “Super-resolution microscopy reveals fine detail of cellular mesh” 

    UC Berkeley

    UC Berkeley

    January 30, 2018
    Robert Sanders
    rlsanders@berkeley.edu

    One of today’s sharpest imaging tools, super-resolution microscopy, produces sparkling images of what until now has been the blurry interior of cells, detailing not only the cell’s internal organs and skeleton, but also providing insights into cells’ amazing flexibility.

    1
    Super-resolution microscopy reveals the two-dimensional triangular protein meshwork underlying the membrane of the red blood cell. Ke Xu image.

    In the current issue of the journal Cell Reports, Ke Xu and his colleagues at UC Berkeley use the technique to provide a sharp view of the geodesic mesh that supports the outer membrane of a red blood cell, revealing why such cells are sturdy yet flexible enough to squeeze through narrow capillaries as they carry oxygen to our tissues.

    The discovery could eventually help uncover how the malaria parasite hijacks this mesh, called the sub-membrane cytoskeleton, when it invades and eventually destroys red blood cells.

    “People know that the parasite interacts with the cytoskeleton, but how it does it is unclear because there has been no good way to look at the structure,” said Xu, an assistant professor of chemistry. “Now that we have resolved what is really going on in a normal healthy cell, we can ask what changes under infection with parasites and how drugs affect the interaction.”

    Typical human cells have a two-dimensional skeleton that supports the outer membrane and a three-dimensional interior skeleton that supports all the organelles inside and serves as a transportation system throughout the cell.

    Red blood cells, however, have only the membrane supports and no internal scaffolding, so they’re basically a balloon filled with molecules of oxygen-carrying hemoglobin. Because of their simpler structure, red blood cells are ideal for studying the skeleton that supports the membrane in all cells.

    Electron microscope images earlier showed that the sub-membrane cytoskeleton in red blood cells is a triangular mesh of proteins, reminiscent of a geodesic dome. But measurements of the size of the triangular subunits were made by flattening out the domed membrane of a dead and dried-out cell, which distorts the structure.

    STORMing the cytoskeleton

    Xu was a postdoctoral fellow in the Harvard University lab of one of the inventors of super-resolution microscopy, Xiaowei Zhuang, and is an expert on the version called STORM (stochastic optical reconstruction microscopy). Super-resolution microscopy gives about 10 times better resolution than standard light microscopy and works well with wet and live cells.

    2
    Labeling one end of the spectrin molecule with a dye reveals where it connects with the actin protein at the vertices of the triangular mesh. Super-resolution microscopy revealed a 80-nanometer distance between vertices, as well as unsuspected gaps in the mesh – weak points that may allow the red blood cell to reshape itself without breaking.

    Using STORM, Xu, former Berkeley postdoc Leiting Pan and graduate student Rui Yan were able to image the full sub-membrane cytoskeleton of fresh red blood cells and discovered that the triangles of the mesh are about half the size of found in earlier measurements done with electron microscopy: each side is 80 nanometers long, instead of 190 nanometers.

    The distinction is critical: The building blocks of the mesh are a protein called spectrin, which can be stretched to a maximum of about 190 nanometers in length. If the mesh were made of stretched spectrin, it would be rigid, Xu said. But since its normal length is a relaxed 80 nanometers, it acts like a spring.
    “It is more like a spring in its relaxed state, where it has much flexibility under compression or stretching, so that gives red blood cells a lot of elasticity under different physiological conditions, such as squeezing through a narrow capillary,” Yan said.

    At the vertices of the mesh, where five to six spectrin proteins come together, is a different protein: actin. Actin is a standard part of the sub-membrane cytoskeleton and one of the main structural components of the cell.

    Tears in the mesh

    Interestingly, STORM revealed never-before-seen holes in the cytoskeletal mesh that may also be critical to its flexibility.

    “This is a defect in the network, but there might be a reason for it,” said Xu, who is also a Chan Zuckerberg Biohub Investigator. “The cell would want to change structure rapidly as it goes through the capillaries, and having those defects is helpful in reorganizing the shape without breaking the mesh. It can act as a weak point as they try to squeeze through things, they can start to bend around those points.”

    3
    Labeling of the spectrin molecule in the axon of a neuron, showing that they are stretched to their full length of 190 nanometers.

    Xu actually discovered the key structural role of spectrin. While still at Harvard, he used STORM to look at the skeletal structure of neurons, and discovered that actin proteins form precisely spaced rings along the entire length of the axon – which can be as much as a foot long – much like the ribs of a snake. They are separated by exactly 190 nanometers, and when he looked through textbooks for proteins with that length, he came across spectrin. He subsequently used STORM to confirm that in its stretched state, spectrin proteins are the spacers between the rings, keeping them precisely separated.

    “The ringed skeleton makes the axon a very stable but bendable structure,” Xu said, whereas the regular spacing may be key to its electrical conductivity.

    Super-resolution microscopy employs a trick to overcome the diffraction limit of light microscopy, which prevents conventional light microscopes from resolving things smaller than half the size of the wavelength of the light, which for visible light is about 300 nanometers.

    4
    STORM can provide clear images of the interior skeleton of a cell, such as this epithelial cell.

    STORM involves attaching a blinking light source to individual molecules and then isolating each light’s position independently of the others, building up a complete image much like the 1880s artists who developed pointillism, producing images from individual dots of paint.

    Typically chemists attach these flashing sources to all molecules of the same type in a cell, such as all actin molecules, but since only a small percentage of the sources blink on at any one time, it’s possible to pinpoint the exact location of each. Today’s best resolution is about 10 nanometers, Xu said, which is about the size of a single protein or molecule.

    The work was supported by the National Natural Science Foundation of China, a Pew Biomedical Scholars Award and a Packard Fellowship for Science and Engineering. Coauthor and postdoc Wan Li contributed to experimental design and data analysis.

    See the full article here .

    Please help promote STEM in your local schools.

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  • richardmitnick 2:20 pm on January 3, 2018 Permalink | Reply
    Tags: A study by UC Berkeley geochemists presents new evidence that high levels of oxygen were not critical to the origin of animals, , , , , UC Berkeley   

    From UC Berkeley: “Which came first: complex life or high atmospheric oxygen?” 

    UC Berkeley

    UC Berkeley

    January 3, 2018
    Robert Sanders
    rlsanders@berkeley.edu

    We and all other animals wouldn’t be here today if our planet didn’t have a lot of oxygen in its atmosphere and oceans. But how crucial were high oxygen levels to the transition from simple, single-celled life forms to the complexity we see today?

    A study by UC Berkeley geochemists presents new evidence that high levels of oxygen were not critical to the origin of animals.

    1
    By measuring the oxidation of iron in pillow basalts from undersea volcanic eruptions, UC Berkeley scientists have more precisely dated the oxygenation of the deep ocean, inferring from that when oxygen levels in the atmosphere rose to current high levels. Credit: National Science Foundation .

    The researchers found that the transition to a world with an oxygenated deep ocean occurred between 540 and 420 million years ago. They attribute this to an increase in atmospheric O2 to levels comparable to the 21 percent oxygen in the atmosphere today.

    This inferred rise comes hundreds of millions of years after the origination of animals, which occurred between 700 and 800 million years ago.

    “The oxygenation of the deep ocean and our interpretation of this as the result of a rise in atmospheric O2 was a pretty late event in the context of Earth history,” said Daniel Stolper, an assistant professor of earth and planetary science at UC Berkeley. “This is significant because it provides new evidence that the origination of early animals, which required O2 for their metabolisms, may have gone on in a world with an atmosphere that had relatively low oxygen levels compared to today.”

    He and postdoctoral fellow Brenhin Keller will report their findings in a paper posted online Jan. 3 in advance of publication in the journal Nature. Keller is also affiliated with the Berkeley Geochronology Center.

    The history of Earth’s oxygen

    Oxygen has played a key role in the history of Earth, not only because of its importance for organisms that breathe oxygen, but because of its tendency to react, often violently, with other compounds to, for example, make iron rust, plants burn and natural gas explode.

    Tracking the concentration of oxygen in the ocean and atmosphere over Earth’s 4.5-billion-year history, however, isn’t easy. For the first 2 billion years, most scientists believe very little oxygen was present in the atmosphere or ocean. But about 2.5-2.3 billion years ago, atmospheric oxygen levels first increased. The geologic effects of this are evident: rocks on land exposed to the atmosphere suddenly began turning red as the iron in them reacted with oxygen to form iron oxides similar to how iron metal rusts.

    Earth scientists have calculated that around this time, atmospheric oxygen levels first exceeded about a hundred thousandth of today’s level (0.001 percent), but remained too low to oxygenate the deep ocean, which stayed largely anoxic.

    By 400 million years ago, fossil charcoal deposits first appear, an indication that atmospheric O2 levels were high enough to support wildfires, which require about 50 to 70 percent of modern oxygen levels, and oxygenate the deep ocean. How atmospheric oxygen levels varied between 2,500 and 400 million years ago is less certain and remains a subject of debate.

    “Filling in the history of atmospheric oxygen levels from about 2.5 billion to 400 million years ago has been of great interest given O2’s central role in numerous geochemical and biological processes. For example, one explanation for why animals show up when they do is because that is about when oxygen levels first approached the high atmospheric concentrations seen today,” Stolper said. “This explanation requires that the two are causally linked such that the change to near-modern atmospheric O2 levels was an environmental driver for the evolution of our oxygen-requiring predecessors.”

    In contrast, some researchers think the two events are largely unrelated. Critical to helping to resolve this debate is pinpointing when atmospheric oxygen levels rose to near modern levels. But past estimates of when this oxygenation occurred range from 800 to 400 million years ago, straddling the period during which animals originated.

    When did oxygen levels change for a second time?

    Stolper and Keller hoped to pinpoint a key milestone in Earth’s history: when oxygen levels became high enough – about 10 to 50 percent of today’s level – to oxygenate the deep ocean. Their approach is based on looking at the oxidation state of iron in igneous rocks formed undersea (referred to as “submarine”) volcanic eruptions, which produce “pillows” and massive flows of basalt as the molten rock extrudes from ocean ridges. Critically, after eruption, seawater circulates through the rocks. Today, these circulating fluids contain oxygen and oxidize the iron in basalts. But in a world with deep-oceans devoid of O2, they expected little change in the oxidation state of iron in the basalts after eruption.


    Eruption of pillow basalts on the ocean floor.

    “Our idea was to study the history of the oxidation state of iron in these basalts and see if we could pinpoint when the iron began to show signs of oxidation and thus when the deep ocean first started to contain appreciable amounts of dissolved O2,” Stolper said.

    To do this, they compiled more than 1,000 published measurements of the oxidation state of iron from ancient submarine basalts. They found that the basaltic iron only becomes significantly oxidized relative to magmatic values between about 540 and 420 million years ago, hundreds of millions of years after the origination of animals. They attribute this change to the rise in atmospheric O2 levels to near modern levels. This finding is consistent with some but not all histories of atmospheric and oceanic O2 concentrations.

    “This work indicates that an increase in atmospheric O2 to levels sufficient to oxygenate the deep ocean and create a world similar to that seen today was not necessary for the emergence of animals,” Stolper said. “Additionally, the submarine basalt record provides a new, quantitative window into the geochemical state of the deep ocean hundreds of millions to billions of years ago.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

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    • stewarthoughblog 12:01 am on January 4, 2018 Permalink | Reply

      Interesting finding and conclusion. What appears to be lacking is why they do not consider it pertinent and critical to the model they are proposing that the essential barrier to cosmic radiation that ozone forms based on some minimum level of oxygen in the atmosphere. The survivability of advanced organisms is highly dependent on the ozone layer, so consideration of the timing of their appearance relative to increase of oxygen levels is significant, unlike Stolper’s incoherent proposition that increasing oxygen levels prompted evolutionary changes that produced advanced organisms.

      Like

  • richardmitnick 2:56 pm on December 23, 2017 Permalink | Reply
    Tags: ADMX Axion Dark Matter Experiment at the University of Washington, , , Cosmic Axion Spin-Precession Experiment (CASPEr), , International Linear Collider in Japan, Large Underground Xenon (LUX) dark matter experiment, LBNL LZ project at SURF Lead SD USA, MACHOs, SIMPs, UC Berkeley,   

    From UC Berkeley: “MACHOs are Dead. WIMPs are a No-Show. Say Hello to SIMPs” 

    UC Berkeley

    UC Berkeley

    December 4, 2017
    Robert Sanders
    rlsanders@berkeley.edu

    The intensive, worldwide search for dark matter, the missing mass in the universe, has so far failed to find an abundance of dark, massive stars or scads of strange new weakly interacting particles, but a new candidate is slowly gaining followers and observational support.

    1
    Fundamental structures of a pion (left) and a proposed SIMP (strongly interacting massive particle). Pions are composed of an up quark and a down antiquark, with a gluon (g) holding them together. A SIMP would be composed of a quark and an antiquark held together by an unknown type of gluon (G). (Kavli IPMU graphic)

    Called SIMPs – strongly interacting massive particles – they were proposed three years ago by UC Berkeley theoretical physicist Hitoshi Murayama, a professor of physics and director of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) in Japan, and former UC Berkeley postdoc Yonit Hochberg, now at Hebrew University in Israel.

    Murayama says that recent observations of a nearby galactic pile-up [Nature] could be evidence for the existence of SIMPs, and he anticipates that future particle physics experiments will discover one of them.

    Murayama discussed his latest theoretical ideas about SIMPs and how the colliding galaxies support the theory in an invited talk Dec. 4 at the 29th Texas Symposium on Relativistic Astrophysics in Cape Town, South Africa.

    Astronomers have calculated that dark matter, while invisible, makes up about 85 percent of the mass of the universe. The solidest evidence for its existence is the motion of stars inside galaxies: Without an unseen blob of dark matter, galaxies would fly apart. In some galaxies, the visible stars are so rare that dark matter makes up 99.9 percent of the mass of the galaxy.

    Theorists first thought that this invisible matter was just normal matter too dim to see: failed stars called brown dwarfs, burned-out stars or black holes. Yet so-called massive compact halo objects – MACHOs – eluded discovery, and earlier this year a survey of the Andromeda galaxy by the Subaru Telescope basically ruled out any significant undiscovered population of black holes.


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

    The researchers searched for black holes left over from the very early universe, so-called primordial black holes, by looking for sudden brightenings produced when they pass in front of background stars and act like a weak lens. They found exactly one – too few to contribute significantly to the mass of the galaxy.

    3
    This Hubble Space Telescope image of the galaxy cluster Abell 3827 shows the ongoing collision of four bright galaxies and one faint central galaxy, as well as foreground stars in our Milky Way galaxy and galaxies behind the cluster (Arc B and Lensed image A) that are distorted because of normal and dark matter within the cluster. SIMPs could explain why the dark matter, unseen but detectable because of the lensing, lags behind the normal matter in the collision.

    “That study pretty much eliminated the possibility of MACHOs; I would say it is pretty much gone,” Murayama said.

    WIMPs — weakly interacting massive particles — have fared no better, despite being the focus of researchers’ attention for several decades. They should be relatively large – about 100 times heavier than the proton – and interact so rarely with one another that they are termed “weakly” interacting. They were thought to interact more frequently with normal matter through gravity, helping to attract normal matter into clumps that grow into galaxies and eventually spawn stars.

    SIMPs interact with themselves, but not others.

    SIMPs, like WIMPs and MACHOs, theoretically would have been produced in large quantities early in the history of the universe and since have cooled to the average cosmic temperature. But unlike WIMPs, SIMPs are theorized to interact strongly with themselves via gravity but very weakly with normal matter. One possibility proposed by Murayama is that a SIMP is a new combination of quarks, which are the fundamental components of particles like the proton and neutron, called baryons. Whereas protons and neutrons are composed of three quarks, a SIMP would be more like a pion in containing only two: a quark and an antiquark.

    4
    Conventional WIMP theories predict that dark matter particles rarely interact. Murayama and Hochberg predict that dark matter SIMPs, comprised of a quark and an antiquark, would collide and interact, producing noticeable effects when the dark matter in galaxies collide. (Kavli IPMU graphic)

    The SIMP would be smaller than a WIMP, with a size or cross section like that of an atomic nucleus, which implies there are more of them than there would be WIMPs. Larger numbers would mean that, despite their weak interaction with normal matter – primarily by scattering off of it, as opposed to merging with or decaying into normal matter – they would still leave a fingerprint on normal matter, Murayama said.

    He sees such a fingerprint in four colliding galaxies within the Abell 3827 cluster, where, surprisingly, the dark matter appears to lag behind the visible matter. This could be explained, he said, by interactions between the dark matter in each galaxy that slows down the merger of dark matter but not that of normal matter, basically stars.

    “One way to understand why the dark matter is lagging behind the luminous matter is that the dark matter particles actually have finite size, they scatter against each other, so when they want to move toward the rest of the system they get pushed back,” Murayama said. “This would explain the observation. That is the kind of thing predicted by my theory of dark matter being a bound state of new kind of quarks.”

    SIMPs also overcome a major failing of WIMP theory: the ability to explain the distribution of dark matter in small galaxies.

    5
    Conventional WIMP theories predict a highly peaked distribution, or cusp, of dark matter in a small area in the center of every galaxy. SIMP theory predicts a spread of dark matter in the center, which is more typical of dwarf galaxies. (Kavli IPMU graphic based on NASA, STScI images)

    “There has been this longstanding puzzle: If you look at dwarf galaxies, which are very small with rather few stars, they are really dominated by dark matter. And if you go through numerical simulations of how dark matter clumps together, they always predict that there is a huge concentration towards the center. A cusp,” Murayama said. “But observations seem to suggest that concentration is flatter: a core instead of a cusp. The core/cusp problem has been considered one of the major issues with dark matter that doesn’t interact other than by gravity. But if dark matter has a finite size, like a SIMP, the particles can go ‘clink’ and disperse themselves, and that would actually flatten out the mass profile toward the center. That is another piece of ‘evidence’ for this kind of theoretical idea.”

    Ongoing searches for WIMPs and axions

    Ground-based experiments to look for SIMPs are being planned, mostly at accelerators like the Large Hadron Collider at CERN in Geneva, where physicists are always looking for unknown particles that fit new predictions.

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    Another experiment at the planned International Linear Collider in Japan could also be used to look for SIMPs.

    ILC schematic, being planned for the Kitakami highland, in the Iwate prefecture of northern Japan

    As Murayama and his colleagues refine the theory of SIMPs and look for ways to find them, the search for WIMPs continues. The Large Underground Xenon (LUX) dark matter experiment in an underground mine in South Dakota has set stringent limits on what a WIMP can look like, and an upgraded experiment called LZ will push those limits further. Daniel McKinsey, a UC Berkeley professor of physics, is one of the co-spokespersons for this experiment, working closely with Lawrence Berkeley National Laboratory, where Murayama is a faculty senior scientist.

    Lux Dark Matter 2 at SURF, Lead, SD, USA

    LBNL LZ project at SURF, Lead, SD, USA

    Physicists are also seeking other dark matter candidates that are not WIMPs. UC Berkeley faculty are involved in two experiments looking for a hypothetical particle called an axion, which may fit the requirements for dark matter. The Cosmic Axion Spin-Precession Experiment (CASPEr), led by Dmitry Budker, a professor emeritus of physics who is now at the University of Mainz in Germany, and theoretician Surjeet Rajendran, a UC Berkeley professor of physics, is planning to look for perturbations in nuclear spin caused by an axion field. Karl van Bibber, a professor of nuclear engineering, plays a key role in the (ADMX-HF), which seeks to detect axions inside a microwave cavity within a strong magnetic field as they convert to photons.

    ADMX Axion Dark Matter Experiment at the University of Washington

    “Of course we shouldn’t abandon looking for WIMPs,” Murayama said, “but the experimental limits are getting really, really important. Once you get to the level of measurement, where we will be in the near future, even neutrinos end up being the background to the experiment, which is unimaginable.”

    Neutrinos interact so rarely with normal matter that an estimated 100 trillion fly through our bodies every second without our noticing, something that makes them extremely difficult to detect.

    “The community consensus is kind of, we don’t know how far we need to go, but at least we need to get down to this level,” he added. “But because there are definitely no signs of WIMPs appearing, people are starting to think more broadly these days. Let’s stop and think about it again.”

    Murayama’s research is supported by the U.S. Department of Energy, National Science Foundation and Japanese Ministry of Education, Culture, Sports, Science and Technology. Murayama is also collaborating with Eric Kuflik of Hebrew University, Tomer Volansky of Tel Aviv University and Jay Wacker of Quora Inc. in Mountain View, California, and Stanford University.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

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  • richardmitnick 1:09 pm on December 9, 2017 Permalink | Reply
    Tags: , Atom interferometry, Blackbody radiation, Hot bodies are attractive, Optical tweezers, , UC Berkeley   

    From UC Berkeley: “Hot bodies are attractive” 

    UC Berkeley

    UC Berkeley

    December 8, 2017
    Robert Sanders
    rlsanders@berkeley.edu

    Our physical attraction to hot bodies is real, according to UC Berkeley physicists.

    To be clear, they’re not talking about sexual attraction to a “hot” human body.

    1
    The blackbody attraction between a hot tungsten cylinder and a cesium atom is 20 times stronger than the gravitational attraction between them. (Holger Müller graphic)

    But the researchers have shown that a glowing object actually attracts atoms, contrary to what most people – physicists included – would guess.

    The tiny effect is much like the effect a laser has on an atom in a device called optical tweezers, which are used to trap and study atoms, a discovery that led to the 1997 Nobel Prize in Physics shared by former UC Berkeley professor Steven Chu, now at Stanford, Claude Cohen-Tannoudji and William D. Phillips.

    Until three years ago, when a group of Austrian physicists predicted it, no one thought that regular light, or even just the heat given off by a warm object – the infrared glow you see when looking through night-vision goggles – could affect atoms in the same way.

    UC Berkeley physicists, who are expert at measuring minute forces using atom interferometry, designed an experiment to check it out. When they measured the force exerted by the so-called blackbody radiation from a warm tungsten cylinder on a cesium atom, the prediction was confirmed.

    The attraction is actually 20 times the gravitational attraction between the two objects, but since gravity is the weakest of all the forces, the effect on cesium atoms – or any atom, molecule or larger object – is usually too small to worry about.

    “It’s hard to find a scenario where this force would stand out,” said co-author Victoria Xu, a graduate student in the physics department at UC Berkeley. “It is not clear it makes a significant effect anywhere. Yet.”

    As gravity measurements become more precise, though, effects this small need to be taken into account. The next generation of experiments to detect gravitational waves from space may use lab-bench atom interferometers instead of the kilometer-long interferometers now in operation. Interferometers typically combine two light waves to detect tiny changes in the distance they’ve traveled; atom interferometers combine two matter waves to detect tiny changes in the gravitational field they’ve experienced.

    3
    Thermal images like this record blackbody radiation, essentially the infrared light given off as a body cools. (iStock image)

    For very precise inertial navigation using atom interferometers, this force would also have to be taken into account.

    “This blackbody attraction has an impact wherever forces are measured precisely, including precision measurements of fundamental constants, tests of general relativity, measurements of gravity and so on,” said senior author Holger Müller, an associate professor of physics. Xu, Müller and their UC Berkeley colleagues published their study in the December issue of the journal Nature Physics.

    Optical tweezers

    Optical tweezers work because light is a superposition of magnetic and electric fields – an electromagnetic wave. The electric field in a light beam makes charged particles move. In an atom or a small sphere, this can separate positive charges, like the nucleus, from negative charges, like the electrons. This creates a dipole, allowing the atom or sphere to act like a tiny bar magnet.
    The electric field in the light wave can then move this induced electric dipole around, just as you can use a bar magnet to shove a piece of iron around.

    Using more than one laser beam, scientists can levitate an atom or bead to conduct experiments.

    With weak, incoherent light, like blackbody radiation from a hot object, the effect is much weaker, but still there, Müller’s team found.

    4
    The shiny tungsten cylinder can be seen at top through a window into the vacuum chamber of the atom interferometer The cesium atoms are launched upwards through the circular opening below the cylinder. (Holger Müller photo)

    They measured the effect by placing a dilute gas of cold cesium atoms – cooled to three-millionths of a degree above absolute zero (300 nanoKelvin) – in a vacuum chamber and launching them upward with a quick pulse of laser light.

    Half are given an extra kick up towards an inch-long tungsten cylinder glowing at 185 degrees Celsius (365 degrees Fahrenheit), while the other half remain unkicked. When the two groups of cesium atoms fall and meet again, their matter waves interfere, allowing the researchers to measure the phase shift caused by the tungsten-cesium interaction, and thus calculate the attractive force of the blackbody radiation.

    “People think blackbody radiation is a classic concept in physics – it was a catalyst for starting the quantum mechanical revolution 100 years ago – but there are still cool things to learn about it,” Xu said.

    The research was funded by the David and Lucile Packard Foundation, National Science Foundation (037166), Defense Advanced Research Projects Agency (033504) and National Aeronautics and Space Administration (041060-002, 041542, 039088, 038706, and 036803). Other co-authors are Philipp Haslinger, Matt Jaffe and Osip Schwartz of UC Berkeley, Matthias Sonnleitner of the University of Glasgow, Monika Ritsch-Marte of the Medical University of Innsbruck in Austria and Helmut Ritsch of the University of Innsbruck.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

    UC Berkeley Seal

     
  • richardmitnick 11:54 am on August 31, 2017 Permalink | Reply
    Tags: Berkeley SETI Research Center, , , , UC Berkeley   

    From UC Berkeley: “Distant galaxy sends out 15 high-energy radio bursts” 

    UC Berkeley

    UC Berkeley

    August 30, 2017
    Robert Sanders
    rlsanders@berkeley.edu

    Breakthrough Listen, an initiative to find signs of intelligent life in the universe, has detected 15 brief but powerful radio pulses emanating from a mysterious and repeating source – FRB 121102 – far across the universe.

    Breakthrough Listen Project

    Fast radio bursts are brief, bright pulses of radio emission from distant but largely unknown sources, and FRB 121102 is the only one known to repeat: more than 150 high-energy bursts have been observed coming from the object, which was identified last year as a dwarf galaxy about 3 billion light years from Earth.

    2
    A sequence of 14 of the 15 detected bursts illustrate their dispersed spectrum and extreme variability. The streaks across the colored energy plot are the bursts appearing at different times and different energies because of dispersion caused by 3 billion years of travel through intergalactic space. In the top frequency spectrum, the dispersion has been removed to show the 300 microsecond pulse spike. Capturing this diverse set of bursts was made possible by the broad bandwidth that can be processed by the Breakthrough Listen backend at the Green Bank Telescope.



    GBO radio telescope, Green Bank, West Virginia, USA

    Possible explanations for the repeating bursts range from outbursts from rotating neutron stars with extremely strong magnetic fields – so-called magnetars – to a more speculative idea: They are directed energy sources, powerful laser bursts used by extraterrestrial civilizations to power spacecraft, akin to Breakthrough Starshot’s plan to use powerful laser pulses to propel nano-spacecraft to our solar system’s nearest star, Proxima Centauri.

    Breakthrough Starshot

    “Bursts from this source have never been seen at this high a frequency,” said Andrew Siemion, director of the Berkeley SETI Research Center and of the Breakthrough Listen program.

    As astronomers around the globe try to understand the mechanism generating fast radio bursts, they have repeatedly turned their radio telescopes on FRB 121102. Siemion and his team alerted the astronomical community to the high-frequency activity via an Astronomer’s Telegram on Monday evening, Aug. 28.

    “As well as confirming that the source is in a newly active state, the high resolution of the data obtained by the Listen instrument will allow measurement of the properties of these mysterious bursts at a higher precision than ever possible before,” said Breakthrough Listen postdoctoral researcher Vishal Gajjar, who discovered the increased activity.

    First detected with the Parkes Telescope in Australia, fast radio bursts have now been seen by several radio telescopes around the world.

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

    FRB 121102 was discovered on Nov. 2, 2012, (hence its name) and in 2015 it was the first fast radio burst seen to repeat, ruling out theories of bursts’ origins that involved the catastrophic destruction of the progenitor, at least in this instance.

    Regardless of FRB 121102’s ultimate source, when the recently detected pulses left their host galaxy, our solar system was less than 2 billion years old, noted Steve Croft, a Breakthrough Listen astronomer at UC Berkeley. Life on Earth consisted only of single-celled organisms; it would be another billion years before even the simplest multi-cellular life began to evolve.

    As part of Breakthrough Listen’s program to observe nearby stars and galaxies for signatures of extraterrestrial technology, the project science team at UC Berkeley added FRB 121102 to its list of targets. In the early hours of Saturday, Aug. 26, Gajjar observed that area of the sky using the Breakthrough Listen backend instrument at the Green Bank Telescope in West Virginia.

    The instrument accumulated 400 terabytes (a million million bytes) of data over a five-hour period, observing across the entire 4 to 8 GHz frequency band. This large dataset was searched for signatures of short pulses from the source over a broad range of frequencies, with a characteristic dispersion, or delay as a function of frequency, caused by the presence of gas in space between Earth and the source. The distinctive shape that the dispersion imposes on the initial pulse is an indicator of the amount of material between us and the source, and hence an indicator of the distance to the host galaxy.

    Analysis by Gajjar and the Breakthrough Listen team revealed 15 new pulses from FRB 121102. The observations show for the first time that fast radio bursts emit at higher frequencies than previously observed, with the brightest emission occurring at around 7 GHz.

    “The extraordinary capabilities of the backend receiver, which is able to record several gigahertz of bandwidth at a time, split into billions of individual channels, enable a new view of the frequency spectrum of FRBs, and should shed additional light on the processes giving rise to FRB emission.” Gajjar said.

    “Whether or not fast radio bursts turn out to be signatures of extraterrestrial technology, Breakthrough Listen is helping to push the frontiers of a new and rapidly growing area of our understanding of the universe around us,” Siemion said.

    See the full article here .
    Previously noted briefly here .

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  • richardmitnick 2:55 pm on August 5, 2017 Permalink | Reply
    Tags: , , , Climate policies study shows Inland Empire economic boon, , , UC Berkeley   

    From UC Berkeley: “Climate policies study shows Inland Empire economic boon” 

    UC Berkeley

    UC Berkeley

    August 3, 2017
    Jacqueline Sullivan

    1
    UC Berkeley researchers found that the proliferation of renewable energy plants — like the San Gorgonio Pass wind farm shown above — is responsible for over 90 percent of the direct benefit of California’s climate and clean energy policies in the Inland Empire. (iStock photo).

    According to the first comprehensive study of the economic effects of climate programs in California’s Inland Empire, Riverside and San Bernardino counties experienced a net benefit of $9.1 billion in direct economic activity and 41,000 jobs from 2010 through 2016.

    Researchers at UC Berkeley’s Center for Labor Research and Education and the Center for Law, Energy and the Environment at Berkeley Law report that many of these jobs were created by one-time construction investments associated with building renewable energy power plants. These investments, they say, helped rekindle the construction industry, which experienced major losses during the Great Recession.

    When accounting for the spillover effects, the researchers report in their study commissioned by nonpartisan, nonprofit group Next 10, that state climate policies resulted in a total of $14.2 billion in economic activity and more than 73,000 jobs for the region during the same seven years.

    Study focal points

    2
    Inland Empire residents are at especially high risk for pollution-related health conditions. This hazy view from a Rancho Cucamonga street attests to the region’s smog problem. (Photo by Mikeetc via Creative Commons).

    Because smog in San Bernardino and Riverside counties is consistently among the worst in the state, residents are at especially high risk of pollution-related health conditions.

    “California has many at-risk communities — communities that are vulnerable to climate change, but also vulnerable to the policy solutions designed to slow climate change,” said Betony Jones, lead author of the report and associate director of the Green Economy Program at UC Berkeley’s Center for Labor Research and Education.

    In the Inland Empire, per capita income is approximately $23,000, compared to the state average of $30,000, and 17.5 percent of the residents of Riverside and San Bernardino counties live below the poverty line, compared to 14.7 percent of all Californians.

    The Net Economic Impacts of California’s Major Climate Programs in the Inland Empire study comes out right after the state’s recent decision to extend California’s cap-and-trade program, and as other states and countries look to California as a model.

    Cap-and-trade

    After accounting for compliance spending and investment of cap-and-trade revenue, researchers found cap and trade had net economic impacts of $25.7 million in San Bernardino and Riverside counties in the first four years of the program, from 2013 to 2016.

    That includes $900,000 in increased tax revenue and net employment growth of 154 jobs through the Inland Empire economy. When funds that have been appropriated but have not yet been spent are included, projected net economic benefits reach nearly $123 million, with 945 jobs created and $5.5 million in tax revenue.

    Proliferation of renewables

    The researchers found that the proliferation of renewable energy plants is responsible for over 90 percent of the direct benefit of California’s climate and clean energy policies in the Inland Empire. As of October 2016, San Bernardino and Riverside Counties were home to more than 17 percent of the state’s renewable generation capacity, according the California Energy Commission.

    3
    Researchers found that altogether, renewables like the solar panels pictured above, contributed more than 60,000 net jobs to the regional economy over seven years. (iStock photo)

    “Even after accounting for construction that would have taken place in a business-as-usual scenario, new renewable power plants created the largest number of jobs in the region over the seven-year period, generating 29,000 high-skilled, high-quality construction jobs,” said Jones.

    The authors compared the jobs created in the generation of renewable electricity with those that would have been created by maintaining natural gas electricity generation. “While renewables create fewer direct jobs, the multiplier effects are greater in the Inland Empire economy,” Jones said. “Altogether, renewable generation contributed over 60,000 net jobs to the regional economy over seven years.”

    Rooftop solar, energy efficiency programs

    The report looks at the costs and benefits of the California Solar Initiative, the federal renewables Investment Tax Credit, and investor-owned utility energy efficiency programs, which provide direct incentives for solar installation and energy efficiency retrofits at homes, businesses and institutions. These programs provided about $1.1 billion in subsidies for distributed solar and $612 million for efficiency in the Inland Empire between 2010 and 2016.

    While researchers calculated benefits for these two programs separately, they identified the costs of these programs to electricity ratepayers together. When the benefits are weighed against these costs, the total net impact of both programs resulted in the creation of more than 12,000 jobs and $1.68 billion across the economy over the seven years studied.

    The report’s authors suggest that officials and/or policymakers:

    Develop a comprehensive program for transportation, the greatest challenge facing in California’s climate goals;
    Expand energy efficiency programs to reduce energy use in the existing building and housing stock while reducing energy costs and creating jobs and economic activity;
    Ensure that the Inland Empire receives appropriate statewide spending based on its economic and environmental needs;
    Develop transition programs for workers and communities affected by the decline of the Inland Empire’s greenhouse gas-emitting industries.

    “California continues to demonstrate leadership on climate and clean energy, and results like these show that California’s models can be exported,” said Ethan Elkind, climate director at the UC Berkeley Center for Law, Energy and the Environment.

    Noel Perry, founder of Next 10, said the report gives policymakers and stakeholders the concrete data needed to weigh policy options and investments in the Inland Empire and beyond.

    See the full article here .

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  • richardmitnick 4:23 pm on June 14, 2017 Permalink | Reply
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    From UC Berkeley: “New evidence that all stars are born in pairs” 

    UC Berkeley

    UC Berkeley

    June 13, 2017
    Robert Sanders
    rlsanders@berkeley.edu

    Did our sun have a twin when it was born 4.5 billion years ago?

    1
    Radio image of a very young binary star system, less than about 1 million years old, that formed within a dense core (oval outline) in the Perseus molecular cloud. All stars likely form as binaries within dense cores. (SCUBA-2 survey image by Sarah Sadavoy, CfA)

    Almost certainly yes — though not an identical twin. And so did every other sunlike star in the universe, according to a new analysis by a theoretical physicist from UC Berkeley and a radio astronomer from the Smithsonian Astrophysical Observatory at Harvard University.

    Many stars have companions, including our nearest neighbor, Alpha Centauri, a triplet system.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    Astronomers have long sought an explanation. Are binary and triplet star systems born that way? Did one star capture another? Do binary stars sometimes split up and become single stars?

    Astronomers have even searched for a companion to our sun, a star dubbed Nemesis because it was supposed to have kicked an asteroid into Earth’s orbit that collided with our planet and exterminated the dinosaurs. It has never been found.

    The new assertion is based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, and a mathematical model that can explain the Perseus observations only if all sunlike stars are born with a companion.

    “We are saying, yes, there probably was a Nemesis, a long time ago,” said co-author Steven Stahler, a UC Berkeley research astronomer.

    “We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years.”

    2
    A radio image of a triple star system forming within a dusty disk in the Perseus molecular cloud obtained by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. (Image: Bill Saxton, ALMA (ESO/NAOJ/NRAO), NRAO/AUI/NSF)

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

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

    In this study, “wide” means that the two stars are separated by more than 500 astronomical units, or AU, where one astronomical unit is the average distance between the sun and Earth (93 million miles). A wide binary companion to our sun would have been 17 times farther from the sun than its most distant planet today, Neptune.

    Based on this model, the sun’s sibling most likely escaped and mixed with all the other stars in our region of the Milky Way galaxy, never to be seen again.

    “The idea that many stars form with a companion has been suggested before, but the question is: how many?” said first author Sarah Sadavoy, a NASA Hubble fellow at the Smithsonian Astrophysical Observatory. “Based on our simple model, we say that nearly all stars form with a companion. The Perseus cloud is generally considered a typical low-mass star-forming region, but our model needs to be checked in other clouds.”

    The idea that all stars are born in a litter has implications beyond star formation, including the very origins of galaxies, Stahler said.

    Stahler and Sadavoy posted their findings in April on the arXiv server. Their paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.

    Stars birthed in ‘dense cores’

    Astronomers have speculated about the origins of binary and multiple star systems for hundreds of years, and in recent years have created computer simulations of collapsing masses of gas to understand how they condense under gravity into stars. They have also simulated the interaction of many young stars recently freed from their gas clouds. Several years ago, one such computer simulation by Pavel Kroupa of the University of Bonn led him to conclude that all stars are born as binaries.

    3
    This infrared image from the Hubble Space Telescope contains a bright, fan-shaped object (lower right quadrant) thought to be a binary star that emits light pulses as the two stars interact. The primitive binary system is located in the IC 348 region of the Perseus molecular cloud and was included in the study by the Berkeley/Harvard team. (Image: NASA, ESA and J. Muzerolle, STScI)

    NASA/ESA Hubble Telescope

    Yet direct evidence from observations has been scarce. As astronomers look at younger and younger stars, they find a greater proportion of binaries, but why is still a mystery.

    “The key here is that no one looked before in a systematic way at the relation of real young stars to the clouds that spawn them,” Stahler said. “Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution. We now believe that most stars, which are quite similar to our own sun, form as binaries. I think we have the strongest evidence to date for such an assertion.”

    According to Stahler, astronomers have known for several decades that stars are born inside egg-shaped cocoons called dense cores, which are sprinkled throughout immense clouds of cold, molecular hydrogen that are the nurseries for young stars. Through an optical telescope, these clouds look like holes in the starry sky, because the dust accompanying the gas blocks light from both the stars forming inside and the stars behind. The clouds can, however, be probed by radio telescopes, since the cold dust grains in them emit at these radio wavelengths, and radio waves are not blocked by the dust.

    The Perseus molecular cloud is one such stellar nursery, about 600 light-years from Earth and about 50 light-years long. Last year, a team of astronomers completed a survey that used the Very Large Array [see above], a collection of radio dishes in New Mexico, to look at star formation inside the cloud. Called VANDAM, it was the first complete survey of all young stars in a molecular cloud, that is, stars less than about 4 million years old, including both single and mulitple stars down to separations of about 15 astronomical units. This captured all multiple stars with a separation of more than about the radius of Uranus’ orbit — 19 AU — in our solar system.

    4
    A dark molecular cloud, Barnard 68, is filled with gas and dust that block the light from stars forming inside as well as stars and galaxies located behind it. These and other stellar nurseries, like the Perseus molecular cloud, can only be probed by radio waves. Credit: FORS Team, 8.2-meter VLT Antu, ESO

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

    ESO/FORS1

    Stahler heard about the survey after approaching Sadavoy, a member of the VANDAM team, and asking for her help in observing young stars inside dense cores. The VANDAM survey produced a census of all Class 0 stars – those less than about 500,000 years old – and Class I stars – those between about 500,000 and 1 million years old. Both types of stars are so young that they are not yet burning hydrogen to produce energy.

    Sadavoy took the results from VANDAM and combined them with additional observations that reveal the egg-shaped cocoons around the young stars. These additional observations come from the Gould Belt Survey with SCUBA-2 on the James Clerk Maxwell Telescope in Hawaii.


    East Asia Observatory James Clerk Maxwell telescope, Mauna Kea, Hawaii, USA

    By combining these two data sets, Sadavoy was able to produce a robust census of the binary and single-star populations in Perseus, turning up 55 young stars in 24 multiple-star systems, all but five of them binary, and 45 single-star systems.

    Using these data, Sadavoy and Stahler discovered that all of the widely separated binary systems — those with stars separated by more than 500 AU — were very young systems, containing two Class 0 stars. These systems also tended to be aligned with the long axis of the egg-shaped dense core. The slightly older Class I binary stars were closer together, many separated by about 200 AU, and showed no tendency to align along the egg’s axis.

    “This has not been seen before or tested, and is super interesting,” Sadavoy said. “We don’t yet know quite what it means, but it isn’t random and must say something about the way wide binaries form.”

    Egg-shaped cores collapse into two centers

    Stahler and Sadavoy mathematically modeled various scenarios to explain this distribution of stars, assuming typical formation, breakup and orbital shrinking times. They concluded that the only way to explain the observations is to assume that all stars of masses around that of the sun start off as wide Class 0 binaries in egg-shaped dense cores, after which some 60 percent split up over time. The rest shrink to form tight binaries.

    “As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis,” he said. “These centers of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars.”

    “Within our picture, single low-mass, sunlike stars are not primordial,” Stahler added. “They are the result of the breakup of binaries. ”

    Their theory implies that each dense core, which typically comprises a few solar masses, converts twice as much material into stars as was previously thought.

    Stahler said that he has been asking radio astronomers to compare dense cores with their embedded young stars for more than 20 years, in order to test theories of binary star formation. The new data and model are a start, he says, but more work needs to be done to understand the physics behind the rule.

    Such studies may come along soon, because the capabilities of a now-upgraded VLA and the ALMA telescope in Chile, plus the SCUBA-2 survey in Hawaii, “are finally giving us the data and statistics we need. This is going to change our understanding of dense cores and the embedded stars within them,” Sadavoy said.

    RELATED INFORMATION

    Embedded binaries and their dense cores (accepted in MNRAS)
    VANDAM website
    Gould Belt Survey website

    See the full article here .

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  • richardmitnick 8:08 am on May 11, 2017 Permalink | Reply
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    From UC Berkeley: “Waves of lava seen in Io’s largest volcanic crater” 

    UC Berkeley

    UC Berkeley

    May 10, 2017
    Robert Sanders
    rlsanders@berkeley.edu

    1
    On March 8, 2015, Jupiter’s moon Europa passed in front of Io, allowing detailed mapping of the bright volcanic crater called Loki Patera (upper left). (Katherine de Kleer image.)

    Taking advantage of a rare orbital alignment between two of Jupiter’s moons, Io and Europa, researchers have obtained an exceptionally detailed map of the largest lava lake on Io, the most volcanically active body in the solar system.

    On March 8, 2015, Europa passed in front of Io, gradually blocking out light from the volcanic moon. Because Europa’s surface is coated in water ice, it reflects very little sunlight at infrared wavelengths, allowing researchers to accurately isolate the heat emanating from volcanoes on Io’s surface.

    The infrared data showed that the surface temperature of Io’s massive molten lake steadily increased from one end to the other, suggesting that the lava had overturned in two waves that each swept from west to east at about a kilometer (3,300 feet) per day.

    Overturning lava is a popular explanation for the periodic brightening and dimming of the hot spot, called Loki Patera after the Norse god. (A patera is a bowl-shaped volcanic crater.) The most active volcanic site on Io, which itself is the most volcanically active body in the solar system, Loki Patera is about 200 kilometers (127 miles) across. The hot region of the patera has a surface area of 21,500 square kilometers, larger than Lake Ontario.

    Earthbound astronomers first noticed Io’s changing brightness in the 1970s, but only when the Voyager 1 and 2 spacecraft flew by in 1979 did it become clear that this was because of volcanic eruptions on the surface. Despite highly detailed images from NASA’s Galileo mission in the late 1990s and early 2000s, astronomers continue to debate whether the brightenings at Loki Patera – which occur every 400 to 600 days – are due to overturning lava in a massive lava lake, or periodic eruptions that spread lava flows over a large area.
    “If Loki Patera is a sea of lava, it encompasses an area more than a million times that of a typical lava lake on Earth,” said Katherine de Kleer, a UC Berkeley graduate student and the study’s lead author. “In this scenario, portions of cool crust sink, exposing the incandescent magma underneath and causing a brightening in the infrared.”


    A simulation of two resurfacing waves sweeping around Loki Patera at different rates and converging in the southeast corner. (Katherine de Kleer video)

    “This is the first useful map of the entire patera,” said co-author Ashley Davies, of the Jet Propulsion Laboratory in Pasadena, who has studied Io’s volcanoes for many years. “It shows not one but two resurfacing waves sweeping around the patera. This is much more complex than what was previously thought”.

    “This is a step forward in trying to understand volcanism on Io, which we have been observing for more than 15 years, and in particular the volcanic activity at Loki Patera,” said Imke de Pater, a UC Berkeley professor of astronomy.

    De Kleer is lead author of a paper reporting the new findings that will be published May 11 in the journal Nature.

    Binocular telescope turns two eyes on Io

    The images were obtained by the twin 8.4-meter (27.6-foot) mirrors of the Large Binocular Telescope Observatory in the mountains of southeast Arizona, linked together as an interferometer using advanced adaptive optics to remove atmospheric blurring.

    U Arizona Large Binocular Telescope, Mount Graham, Arizona, USA

    The facility is operated by an international consortium headquartered at the University of Arizona in Tucson.


    Animation of Europa sweeping across Loki Patera and obscuring different portions of its floor. The lower panels show the infrared intensity of the lava lake as a function of time as it is covered (ingress) and uncovered (egress) by Europa. The red curve is the best-fit map to the observations. (Katherine de Kleer video)

    “Two years earlier, the LBTO had provided the first ground-based images of two separate hot spots within Loki Patera, thanks to the unique resolution offered by the interferometric use of LBT, which is equivalent to what a 23-meter (75-foot) telescope would provide,” noted co-author and LBTO director Christian Veillet. “This time, however, the exquisite resolution was achieved thanks to the observation of Loki Patera at the time of an occultation by Europa.”

    Europa took about 10 seconds to completely cover Loki Patera. “There was so much infrared light available that we could slice the observations into one-eighth-second intervals during which the edge of Europa advanced only a few kilometers across Io’s surface,” said co-author Michael Skrutskie, of the University of Virginia, who led the development of the infrared camera used for this study. “Loki was covered from one direction but revealed from another, just the arrangement needed to make a real map of the distribution of warm surface within the patera.”

    These observations gave the astronomers a two-dimensional thermal map of Loki Patera with a resolution better than 10 kilometers (6.25 miles), 10 times better than normally possible with the LBT Interferometer at this wavelength (4.5 microns). The temperature map revealed a smooth temperature variation across the surface of the lake, from about 270 Kelvin at the western end, where the overturning appeared to have started, to 330 Kelvin at the southeastern end, where the overturned lava was freshest and hottest.
    Using information on the temperature and cooling rate of magma derived from studies of volcanoes on Earth, de Kleer was able to calculate how recently new magma had been exposed at the surface. The results – between 180 and 230 days before the observations at the western end and 75 days before at the eastern – agree with earlier data on the speed and timing of the overturn.

    Interestingly, the overturning started at different times on two sides of a cool island in the center of the lake that has been there ever since Voyager photographed it in 1979.

    2
    A heat map of Io’s lava lake Loki Patera, showing how the surface is cooler in the northwest (1 and 2) where the lava overturn began, and hottest in the southeast (3), where the hotter magma was more recently exposed. The entire lake surface overturned in about three months time. Katherine de Kleer graphic.

    “The velocity of overturn is also different on the two sides of the island, which may have something to do with the composition of the magma or the amount of dissolved gas in bubbles in the magma,” de Kleer said. “There must be differences in the magma supply to the two halves of the patera, and whatever is triggering the start of overturn manages to trigger both halves at nearly the same time but not exactly. These results give us a glimpse into the complex plumbing system under Loki Patera.”

    Lava lakes like Loki Patera overturn because the cooling surface crust slowly thickens until it becomes denser than the underlying magma and sinks, pulling nearby crust with it in a wave that propagates across the surface. According to de Pater, as the crust breaks apart, magma may spurt up as fire fountains, akin to what has been seen in lava lakes on Earth, but on a smaller scale.

    4
    From their infrared measurements, the team deduced the age of the lava at the surface of Loki Patera. The youngest is in the lower right, having overturned most recently, about 75 days before the observations. Katherine de Kleer graphic.De Kleer and de Pater are eager to observe other Io occultations to verify their findings, but they’ll have to wait until the next alignment in 2021. For now, de Kleer is happy that the interferometer linking the two telescopes, the adaptive optics on each and the unique occultation came together as planned that night two years ago.

    “We weren’t sure that such a complex observation was even going to work,” she said, “but we were all surprised and pleased that it did.”

    In addition to de Kleer, Skrutskie, Davies, Veillet and de Pater, co-authors of the paper are J. Leisenring, P. Hinz, E. Spalding and A. Vaz of the University of Arizona’s Steward Observatory, and Al Conrad of the Large Binocular Telescope Observatory, A. Resnick of Amherst College, V. Bailey of Stanford University, D. Defrère of the University of Liège, A. Skemer of UC Santa Cruz and C.E. Woodward of the University of Minnesota.

    See the full article here .

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  • richardmitnick 12:43 pm on May 3, 2017 Permalink | Reply
    Tags: , , SPACE SCIENCE LAB, UC Berkeley   

    From SSL at UC Berkeley: “Solar Array Cooling System Coming Together on Solar Probe Plus” 

    UC Berkeley

    UC Berkeley

    Space Science Labs UC Berkeley

    Space Science Lab

    2
    The Solar Array Cooling System on Solar Probe Plus has one critical job – to protect the NASA spacecraft’s solar arrays from incineration as it moves through the blazing atmosphere of the sun.

    Several key elements of that system are now on board the spacecraft, installed last week during ongoing integration and test operations at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. On April 5, engineers carefully attached the deck that holds the solar array cooling system components, solar array cooling system radiators and the truss structure assembly, or TSA. The TSA will support the spacecraft’s signature 8-foot-wide, 4.5-inch-thick carbon-carbon foam heat shield, as well components from the FIELDS experiment and Solar Wind Electrons, Alphas and Protons (SWEAP) suite that will make direct measurements of the charged particles and electrical fields in the solar environment.

    Solar Probe Plus is on track for launch during a 20-day window that opens July 31, 2018. Integration and testing will continue at APL through November; after that, the spacecraft will be moved to NASA Goddard Space Flight Center in Greenbelt, Maryland, for four months of final space-environmental testing, it is then shipped to Kennedy Space Center/Cape Canaveral Air Force Station, Florida, in March 2018 for final launch preparations. APL designed, is building, and will operate Solar Probe Plus for NASA.

    3
    Mission integration and test team members secure the deck holding the structure assembly and several other critical thermal-protection components atop NASA’s Solar Probe Plus spacecraft body on April 5, 2017, in the cleanroom at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. NASA/Johns Hopkins University Applied Physics Laboratory

    See the full article here .

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  • richardmitnick 8:43 am on February 16, 2017 Permalink | Reply
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    From UC Berkeley: “UC Berkeley, NASA looking for citizen scientists to help find Planet 9” 

    UC Berkeley

    UC Berkeley

    February 15, 2017
    Robert Sanders
    rlsanders@berkeley.edu

    1
    A previously cataloged brown dwarf named WISE 0855−0714 shows up as a moving
    orange dot (upper left) in this loop of WISE images spanning five years. By viewing
    movies like this, anyone can help discover more brown dwarfs or even a 9th planet. (NASA/WISE images)

    Elusive planets and dim failed stars may be lurking around the edges of our solar system, and astronomers from NASA and UC Berkeley want the public’s help to hunt them down.

    Through a new website called Backyard Worlds: Planet 9, anyone can now help search for objects far beyond the orbit of our farthest planet, Neptune, by viewing brief “flipbook” movies made from images captured by NASA’s Wide-field Infrared Survey Explorer (WISE) mission. A faint spot seen moving through background stars might be a new and distant planet orbiting the sun or a nearby brown dwarf.

    NASA/WISE Telescope
    NASA/WISE Telescope

    WISE’s infrared images cover the entire sky about six times over. This has allowed astronomers to search the images for faint, glowing objects that change position over time, which means they are relatively close to Earth. Objects that produce their own faint infrared glow would have to be large, Neptune-size planets or brown dwarfs, which are slightly smaller than stars.

    UC Berkeley postdoctoral researcher Aaron Meisner, a physicist who specializes in analyzing WISE images, has automated the search using computers, but he jumped at the idea by NASA astronomer Marc Kuchner to ask the public to eyeball the millions of WISE images. NASA and its collaborators, including UC Berkeley, are launching the planet and brown dwarf search Feb. 15.

    “Automated searches don’t work well in some regions of the sky, like the plane of the Milky Way galaxy, because there are too many stars, which confuses the search algorithm,” said Meisner, who last month published the results of an automated survey of 5 percent of the WISE data, which revealed no new objects. Online volunteers “using the powerful ability of the human brain to recognize motion” may be luckier, he said.

    “Backyard Worlds: Planet 9 has the potential to unlock once-in-a-century discoveries, and it’s exciting to think they could be spotted first by a citizen scientist,” he added.

    “There are just over four light-years between Neptune, the farthest known planet in our solar system, and Proxima Centauri, the nearest star, and much of this vast territory is unexplored,” said Kuchner, the lead researcher and an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    “Because there’s so little sunlight, even large objects in that region barely shine in visible light. But by looking in the infrared, WISE may have imaged objects we otherwise would have missed.”

    Planet 9

    People have long theorized about unknown planets far beyond Neptune and the dwarf planet Pluto, but until recently there was no evidence to support the idea. Last year, however, Caltech astronomers Mike Brown and Konstantin Batygin found indirect evidence for the existence of an as-yet-unseen ninth planet in the solar system’s outer reaches. This “Planet 9” would be similar in size to Neptune, but up to a thousand times farther from the sun than Earth, and would orbit the sun perhaps once every 15,000 years. It would be so faint as to have so far evaded discovery.


    Video courtesy of the American Museum of Natural History.

    At the moment, the existence of Planet 9 is still under debate. Meisner thinks it’s more likely that volunteers will find brown dwarfs in the solar neighborhood. While Planet 9 would look very blue in WISE time-lapse animations, brown dwarfs would look very red and move across the sky more slowly.

    WISE images have already turned up hundreds of previously unknown brown dwarfs, including the sun’s third- and fourth-closest known neighbors. He hopes that the Backyard Worlds search will turn up a new nearest neighbor to our sun.

    “We’ve pre-processed the WISE data we’re presenting to citizen scientists in such a way that even the faintest moving objects can be detected, giving us an advantage over all previous searches,” Meisner said. Moving objects flagged by participants will be prioritized by the science team for later follow-up observations by professional astronomers. Participants will share credit for their discoveries in any scientific publications that result from the project.

    2
    A very blue Neptune-like planet, dubbed Planet 9, may be lurking dozens of times further from the sun than Pluto, as depicted in this artist’s rendering. Citizen scientists who join the Backyard Worlds: Planet 9 project may be the first to spot it. (NASA image)

    WISE and NEOWISE

    The WISE telescope scanned the entire sky between 2010 and 2011, producing the most comprehensive survey at mid-infrared wavelengths currently available. With the completion of its primary mission, WISE was shut down in 2011, then reactivated in 2013 and given a new mission: assisting NASA’s efforts to identify potentially hazardous near-Earth objects, which are asteroids and comets in the vicinity of our planet. The mission was renamed the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE).

    The new website uses all of the WISE and NEOWISE data to search for unknown objects in and beyond our own solar system, including the putative Planet 9. If Planet 9 exists and is as bright as some predict, it could show up in WISE data.

    Meisner said WISE is uniquely suited for discovering extremely cold brown dwarfs, which can be invisible to the biggest ground-based telescopes despite being very close.

    “Brown dwarfs form like stars but evolve like planets, and the coldest ones are much like Jupiter,” said team member Jackie Faherty, an astronomer at the American Museum of Natural History in New York. “By using Backyard Worlds: Planet 9, the public can help us discover more of these strange rogue worlds.”

    Backyard Worlds: Planet 9 is a collaboration between NASA, UC Berkeley, the American Museum of Natural History in New York, Arizona State University, the Space Telescope Science Institute in Baltimore and Zooniverse, a collaboration of scientists, software developers and educators that collectively develops and manages citizen-science projects on the internet. Zooniverse will spread the word among its many citizen volunteers

    NASA’s Jet Propulsion Laboratory in Pasadena, California, manages and operates WISE, part of NASA’s Explorers Program.

    Meisner, who specializes in creating high-resolution maps of the universe, is also currently working on the Dark Energy Spectroscopic Instrument, a project at Lawrence Berkeley National laboratory that seeks to learn how mysterious dark energy affects the expansion of the universe.

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018
    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018

    Follow Backyard Worlds: Planet 9 on Facebook or Twitter, @backyardworlds.

    RELATED INFORMATION

    Backyard Worlds: Planet 9 Zooniverse Project
    Searching for Planet Nine with Coadded WISE and NEOWISE-Reactivation Images
    FindPlanetNine Blog [link did not work]

    See the full article here .

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