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  • richardmitnick 3:05 pm on January 12, 2018 Permalink | Reply
    Tags: , , , Caltech, Citizen Scientists Discover Five-Planet System, , Exoplanet Explorers   

    From Caltech: “Citizen Scientists Discover Five-Planet System” 

    Caltech Logo

    Caltech

    01/11/2018

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

    Caltech staff scientist Jessie Christiansen is a founder of a citizen-scientist project called Exoplanet Explorers.

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    Artist’s visualization of the K2-138 system, the first multi-planet system discovered by citizen scientists. The central star is slightly smaller and cooler than our sun. The five known planets are all between the size of Earth and Neptune; planet b may potentially be rocky, but planets c, d, e, and f likely contain large amounts of ice and gas. All five planets have orbital periods shorter than 13 days and are all incredibly hot, ranging from 800 to 1800 degrees Fahrenheit. Credit: NASA/JPL-Caltech/R. Hurt (IPAC).

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    Artist’s concept of a top-down view of the K2-138 system discovered by citizen scientists, showing the orbits and relative sizes of the five known planets. Orbital periods of the five planets, shown to scale, fall close to a series of 3:2 mean motion resonances. This indicates that the planets orbiting K2-138, which likely formed much farther away from the star, migrated inward slowly and smoothly. Credit: NASA/JPL-Caltech/R. Hurt (IPAC).

    In its search for exoplanets—planets outside of our solar system—NASA’s Kepler telescope trails behind Earth, measuring the brightness of stars that may potentially host planets. The instrument identifies potential planets around other stars by looking for dips in the brightness of the stars that occur when planets cross in front of, or transit, them. Typically, computer programs flag the stars with these brightness dips, then astronomers look at each one and decide whether or not they truly could host a planet candidate.

    Over the three years of the K2 mission, 287,309 stars have been observed, and tens of thousands more roll in every few months. So how do astronomers sift through all that data?

    Enter the Exoplanet Explorers citizen scientist project, developed by UC Santa Cruz astronomer Ian Crossfield and Caltech staff scientist Jessie Christiansen. Exoplanet Explorers is hosted on Zooniverse, an online platform for crowdsourcing research.

    “People anywhere can log on and learn what real signals from exoplanets look like, and then look through actual data collected from the Kepler telescope to vote on whether or not to classify a given signal as a transit, or just noise,” says Christiansen. “We have each potential transit signal looked at by a minimum of 10 people, and each needs a minimum of 90 percent of ‘yes’ votes to be considered for further characterization.”

    In early April, just two weeks after the initial prototype of Exoplanet Explorers was set up on Zooniverse, it was featured in a three-day event on the ABC Australia television series Stargazing Live. In the first 48 hours after the project was introduced, Exoplanet Explorers received over 2 million classifications from more than 10,000 users. Included in that search was a brand-new dataset from the K2 mission—the reincarnation of the primary Kepler mission, ended three years ago. K2 has a whole new field of view and crop of stars around which to search for planets. No professional astronomer had yet looked through this dataset, called C12.

    Back in California, Crossfield and Christiansen joined NASA astronomer Geert Barentsen, who was in Australia, in examining results as they came in. Using the depth of the transit curve and the periodicity with which it appears, they made estimates for how large the potential planet is and how close it orbits to its star. On the second night of the show, the researchers discussed the demographics of the planet candidates found so far—44 Jupiter-sized planets, 72 Neptune-sized, 44 Earth-sized, and 53 so-called Super Earth’s, which are larger than Earth but smaller than Neptune.

    “We wanted to find a new classification that would be exciting to announce on the final night, so we were originally combing through the planet candidates to find a planet in the habitable zone—the region around a star where liquid water could exist,” says Christiansen. “But those can take a while to validate, to make sure that it really is a real planet and not a false alarm. So, we decided to look for a multi-planet system because it’s very hard to get an accidental false signal of several planets.”

    After this decision, Barentsen left to get a cup of tea. By the time he returned, Christiansen had sorted the crowdsourced data to find a star with multiple transits and discovered a star with four planets orbiting it. Three of the four planets had 100 percent “yes” votes from over 10 people, and the remaining one had 92 percent “yes” votes. This is the first multi-planet system of exoplanets discovered entirely by crowdsourcing.

    After the discovery was announced on Stargazing Live, Christiansen and her colleagues continued to study and characterize the system, dubbed K2-138. They statistically validated the set of planet signals as being “extremely likely,” according to Christiansen, to be signals from true planets. They also found that the planets are orbiting in an interesting mathematical relationship called a resonance, in which each planet takes almost exactly 50 percent longer to orbit the star than the next planet further in. The researchers also found a fifth planet on the same chain of resonances, and hints of a sixth planet as well. A paper describing the system has been accepted for publication in The Astronomical Journal.

    This is the only system with a chain of unbroken resonances in this configuration, and may provide clues to theorists looking to unlock the mysteries of planet formation and migration.

    “The clockwork-like orbital architecture of this planetary system is keenly reminiscent of the Galilean satellites of Jupiter,” says Konstantin Batygin, assistant professor of planetary science and Van Nuys Page Scholar, who was not involved with the study. “Orbital commensurabilities among planets are fundamentally fragile, so the present-day configuration of the K2-138 planets clearly points to a rather gentle and laminar formation environment of these distant worlds.”

    “Some current theories suggest that planets form by a chaotic scattering of rock and gas and other material in the early stages of the planetary system’s life. However, these theories are unlikely to result in such a closely packed, orderly system as K2-138,” says Christiansen. “What’s exciting is that we found this unusual system with the help of the general public.”

    The paper is titled “The K2-138 system: A Near-Resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists [The Astronomical Journal].” In addition to Christiansen, Crossfield, and Barentsen; other coauthors include Chris Lintott, Campbell Allen, Adam McMaster, Grant Miller, Martin Veldthuis of the University of Oxford; Thomas Barclay of NASA Goddard and the University of Maryland; Brooke Simmons of UC San Diego; Caltech postdoctoral scholar Erik Petigura; Joshua Schlieder of NASA Goddard; Courtney Dressing of UC Berkeley; Andrew Vanderburg of Harvard; Sarah Allen and Zach Wolfenbarger of the Adler Planetarium; Brian Cox of the University of Manchester; Julia Zemiro of the Australian Broadcasting Corporation; Caltech Professor of Astronomy Andrew Howard; John Livingston of the University of Tokyo; Evan Sinukoff of the Australian Broadcasting Corporation and the University of Hawai’i at Manoa; Timothy Catron of Arizona State University; Andrew Grey, Joshua Kusch, Ivan Terentev, and Martin Vales of Zooniverse as part of the University of Oxford; and Martti Kristiansen of the Technical University of Denmark. Funding was provided by the NASA Science Mission Directorate, Google, the Alfred P. Sloan Foundation, NASA, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    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 3:45 pm on January 8, 2018 Permalink | Reply
    Tags: , , Caltech, New Technology Will Create Brain Wiring Diagrams, The TRACT method   

    From Caltech: “New Technology Will Create Brain Wiring Diagrams” 

    Caltech Logo

    Caltech

    01/08/2018
    Lori Dajose
    (626) 395-1217
    ldajose@caltech.edu

    Technique allows for maps of the neural connections of entire insect brains, which was previously not possible with other methods.

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    The TRACT method allows for the identification of neurons connected by synapses in a brain circuit. This image shows the olfactory receptor neurons (red) activating the production of a green protein in their synaptically-connected downstream partners. Credit: Courtesy of the Lois Laboratory.

    The human brain is composed of billions of neurons wired together in intricate webs and communicating through electrical pulses and chemical signals. Although neuroscientists have made progress in understanding the brain’s many functions—such as regulating sleep, storing memories, and making decisions—visualizing the entire “wiring diagram” of neural connections throughout a brain is not possible using currently available methods. But now, using Drosophila fruit flies, Caltech researchers have developed a method to easily see neural connections and the flow of communications in real time within living flies. The work is a step forward toward creating a map of the entire fly brain’s many connections, which could help scientists understand the neural circuits within human brains as well.

    A paper describing the work appears online in the December 12 issue of eLife. The research was done in the laboratory of Caltech research professor Carlos Lois.

    “If an electrical engineer wants to understand how a computer works, the first thing that he or she would want to figure out is how the different components are wired to each other,” says Lois. “Similarly, we must know how neurons are wired together in order to understand how brains work.”

    When two neurons connect, they link together with a structure called a synapse, a space through which one neuron can send and receive electrical and chemical signals to or from another neuron. Even if multiple neurons are very close together, they need synapses to truly communicate.

    The Lois laboratory has developed a method for tracing the flow of information across synapses, called TRACT (Transneuronal Control of Transcription). Using genetically engineered Drosophila fruit flies, TRACT allows researchers to observe which neurons are “talking” and which neurons are “listening” by prompting the connected neurons to produce glowing proteins.

    With TRACT, when a neuron “talks”—or transmits a chemical or electrical signal across a synapse—it will also produce and send along a fluorescent protein that lights up both the talking neuron and its synapses with a particular color. Any neurons “listening” to the signal receive this protein, which binds to a so-called receptor molecule—genetically built-in by the researchers—on the receiving neuron’s surface. The binding of the signal protein activates the receptor and triggers the neuron it’s attached to in order to produce its own, differently colored fluorescent protein. In this way, communication between neurons becomes visible. Using a type of microscope that can peer through a thin window installed on the fly’s head, the researchers can observe the colorful glow of neural connections in real time as the fly grows, moves, and experiences changes in its environment.

    Many neurological and psychiatric conditions, such as autism and schizophrenia, are thought to be caused by altered connections between neurons. Using TRACT, scientists can monitor the neuronal connections in the brains of hundreds of flies each day, allowing them to make comparisons at different stages of development, between the sexes, and in flies that have genetic mutations. Thus, TRACT could be used to determine how different diseases perturb the connections within brain circuits. Additionally, because neural synapses change over time, TRACT allows the monitoring of synapse formation and destruction from day to day. Being able to see how and when neurons form or break synapses will be critical to understanding how the circuits in the brain assemble as the animal grows, and how they fall apart with age or disease.

    TRACT can be localized to focus in on the wiring of any particular neural circuit of interest, such as those that control movement, hunger, or vision. Lois and his group tested their method by examining neurons within the well-understood olfactory circuit, the neurons responsible for the sense of smell. Their results confirmed existing data regarding this particular circuit’s wiring diagram. In addition, they examined the circadian circuit, which is responsible for the waking and sleeping cycle, where they detected new possible synaptic connections.

    TRACT, however, can do more than produce wiring diagrams. The transgenic flies can be genetically engineered so that the technique prompts receiving neurons to produce proteins that have a function, rather than colorful proteins that simply trace connections.

    “We could use functional proteins to ask, ‘What happens in the fly if I silence all the neurons that receive input from this one neuron?'” says Lois. “Or, conversely, ‘What happens if I make the neurons that are connected to this neuron hyperactive?’ Our technique not only allows us to create a wiring diagram of the brain, but also to genetically modify the function of neurons in a brain circuit.”

    Previous methods for examining neural connections were time consuming and labor intensive, involving thousands of thin slices of a brain reconstructed into a three-dimensional structure. A laboratory using these techniques could only yield a diagram for a single, small piece of fruit-fly brain per year. Additionally, these approaches could not be performed on living animals, making it impossible to see how neurons communicated in real time.

    Because the TRACT method is completely genetically encoded, it is ideal for use in laboratory animals such as Drosophila and zebrafish; ultimately, Lois hopes to implement the technique in mice to enable the neural tracing of a mammalian brain. “TRACT is a new tool that will allow us to create wiring diagrams of brains and determine the function of connected neurons,” he says. “This information will provide important clues towards understanding the complex workings of the human brain and its diseases.”

    The paper is titled “Tracing neuronal circuits in transgenic animals by transneuronal control of transcription (TRACT).” Other Caltech coauthors include graduate students Ting- Hao Huang and Antuca Callejas; AMGEN undergraduate visiting scholar Peter Niesman; Khorana undergraduate visiting scholar Deepshika Arasu; research technicians Aubrie De La Cruz and Daniel Lee; and Elizabeth Hong (BS ’02), the Clare Boothe Luce Assistant Professor of Neuroscience. Funding was provided by BRAIN award UO1 MH109147 from the National Institutes of Health.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    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 11:59 am on January 7, 2018 Permalink | Reply
    Tags: , Caltech, Nanoscale silicon posts can reflect light differently depending on the angle of incoming light, , , Two Holograms in One Surface   

    From Caltech: “Two Holograms in One Surface” 

    Caltech Logo

    Caltech

    12/11/2017

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

    1
    (Artist’s rendering) In a proof-of-concept, Faraon’s team encoded two holograms (of the Caltech logo and the LMI logo) on a single silicon oxide and aluminum surface. Credit: Andrei Faraon/Caltech

    2
    Nanoposts of varying shapes can act as pixels in two different holograms.
    Credit: Andrei Faraon/Caltech

    Nanoscale silicon posts can reflect light differently depending on the angle of incoming light.

    A team at Caltech has figured out a way to encode more than one holographic image in a single surface without any loss of resolution. The engineering feat overturns a long-held assumption that a single surface could only project a single image regardless of the angle of illumination.

    The technology hinges on the ability of a carefully engineered surface to reflect light differently depending on the angle at which incoming light strikes that surface.

    Holograms are three-dimensional images encoded in two-dimensional surfaces. When the surface is illuminated with a laser, the image seems to pop off the surface and becomes visible. Traditionally, the angle at which laser light strikes the surface has been irrelevant—the same image will be visible regardless. That means that no matter how you illuminate the surface, you will only create one hologram.

    Led by Andrei Faraon, assistant professor of applied physics and materials science in the Division of Engineering and Applied Science, the team developed silicon oxide and aluminum surfaces studded with tens of millions of tiny silicon posts, each just hundreds of nanometers tall. (For scale, a strand of human hair is 100,000 nanometers wide.) Each nanopost reflects light differently due to variations in its shape and size, and based on the angle of incoming light.

    That last property allows each post to act as a pixel in more than one image: for example, acting as a black pixel if incoming light strikes the surface at 0 degrees and a white pixel if incoming light strikes the surface at 30 degrees.

    “Each post can do double duty. This is how we’re able to have more than one image encoded in the same surface with no loss of resolution,” says Faraon (BS ’04), senior author of a paper on the new material published by Physical Review X on December 7.

    “Previous attempts to encode two images on a single surface meant arranging pixels for one image side by side with pixels for another image. This is the first time that we’re aware of that all of the pixels on a surface have been available for each image,” he says.

    As a proof of concept, Faraon and Caltech graduate student Seyedeh Mahsa Kamali (MS ’17) designed and built a surface that when illuminated with a laser straight on (thus, at 0 degrees) projects a hologram of the Caltech logo but when illuminated from an angle of 30 degrees projects a hologram of the logo of the Department of Energy-funded Light-Material Interactions in Energy Conversion Energy Frontier Research Center, of which Faraon is a principal investigator.

    The process was labor intensive. “We created a library of nanoposts with information about how each shape reflects light at different angles. Based on that, we assembled the two images simultaneously, pixel by pixel,” says Kamali, the first author of the Physical Review X paper.

    Theoretically, it would even be possible to encode three or more images on a single surface—though there will be fundamental and practical limits at a certain point. For example, Kamali says that a single degree of difference in the angle of incident light probably cannot be enough to create a new high-quality image. “We are still exploring just how far this technology can go,” she says.

    Practical applications for the technology include improvements to virtual-reality and augmented-reality headsets. “We’re still a long way from seeing this on the market, but it is an important demonstration of what is possible,” Faraon says.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    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.”

    Caltech campus

     
  • richardmitnick 4:00 pm on December 20, 2017 Permalink | Reply
    Tags: , Caltech, , , Update on Neutron Star Smash-Up: Jet Hits a Roadblock   

    From Caltech: “Update on Neutron Star Smash-Up: Jet Hits a Roadblock” 

    Caltech Logo

    Caltech

    12/20/2017

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

    1
    On August 17, 2017, observatories around the world witnessed the collision of two neutron stars. At first, many scientists thought a narrow high-speed jet, directed away from our line of sight, or off-axis, was produced (diagram at left). But observations made at radio wavelengths now indicate the jet hit surrounding material, producing a slower-moving, wide-angle outflow, dubbed a cocoon (pink structure at right). Credit: NRAO/AUI/NSF/D. Berry

    Radio observations are illuminating what happened during recent gravitational-wave event.

    Millions of years ago, a pair of extremely dense stars, called neutron stars, collided in a violent smash-up that shook space and time. On August 17, 2017, both gravitational waves—ripples in space and time—and light waves emitted during that neutron star merger finally reached Earth. The gravitational waves came first and were detected by the twin detectors of the National Science Foundation (NSF)-funded Laser Interferometry Gravitational-wave Observatory (LIGO), aided by the European Virgo observatory.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    The light waves were observed seconds, days, and months later by dozens of telescopes on the ground and in space.

    Now, scientists from Caltech and several other institutions are reporting that light with radio wavelengths continues to brighten more than 100 days after the August 17 event. These radio observations indicate that a jet, launched from the two neutron stars as they collided, is slamming into surrounding material and creating a slower-moving, billowy cocoon.

    “We think the jet is dumping its energy into the cocoon,” says Gregg Hallinan, an assistant professor of astronomy at Caltech. “At first, people thought the material from the collision was coming out in a jet like a firehose, but we are finding that that the flow of material is slower and wider, expanding outward like a bubble.”

    The findings, made with the Karl G. Jansky Very Large Array in New Mexico, the Australia Telescope Compact Array, and the Giant Metrewave Radio Telescope in India, are reported in a new paper in the December 20 online issue of the journal Nature. The lead author is Kunal Mooley (PhD ’15), formerly of the University of Oxford and now a Jansky Fellow at Caltech.

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    CSIRO ATCA at the Paul Wild Observatory, about 25 km west of the town of Narrabri in rural NSW about 500 km north-west of Sydney, AU

    GMRT Radio Telescope, located near Pune, India

    The new data argue against a popular theory describing the aftermath of the neutron star merger—a theory that proposes the event created a fast-moving and beam-like jet thought to be associated with extreme blasts of energy called gamma-ray bursts, and in particular with short gamma-ray bursts, or sGRBs. Scientists think that sGRBs, which pop up every few weeks in our skies, arise from the merger of a pair of neutron stars or the merger of a neutron star with a black hole (an event that has yet to be detected by LIGO). An sGRB is seen when the jet points exactly in the direction of Earth.


    A hydrodynamical simulation shows a cocoon breaking out of the neutron star merger. This model explains the gamma-ray, X-ray, ultraviolet, optical, infrared, and radio data gathered by the GROWTH team from 18 telescopes around the world. Credit: Ehud Nakar (Tel Aviv), Ore Gottlieb (Tel Aviv), Leo Singer (NASA), Mansi Kasliwal (Caltech), and the GROWTH collaboration.

    On August 17, NASA’s Fermi Gamma-ray Space Telescope and the European INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) missions detected gamma rays just seconds after the neutron stars merged.

    NASA/Fermi LAT


    NASA/Fermi Telescope

    ESA/Integral

    The gamma rays were much weaker than what is expected for sGRBS, so the researchers reasoned that a fast and narrowly focused jet was produced but must have been pointed slightly askew from the direction of Earth, or off-axis.

    The radio emission—originally detected 16 days after the August 17 event and still measurable and increasing in strength as of December 2—tells a different story. If the jet had been fast and beam-like, the radio light would have weakened with time as the jet lost energy. The fact that the brightness of the radio light is increasing instead suggests the presence of a cocoon that is choking the jet. The reason for this is complex, but it has to do with the fact that the slower-moving, wider-angle material of the cocoon gives off more radio light than the faster-moving, sharply focused jet material.

    “It’s like the jet was fogged out,” says Mooley. “The jet may be off-axis, but it is not a simple pointed beam or as fast as some people thought. It may be blocked off by material thrown off during the merger, giving rise to a cocoon and emitting light in many different directions.”

    This means that the August 17 event was not a typical sGRB as originally proposed.

    “Standard sGRBs are 10,000 times brighter than we saw for this event,” says Hallinan. “Many people thought this was because the gamma-ray emission was off-axis and thus much weaker. But it turns out that the gamma rays are coming from the cocoon rather than the jet. It is possible that the jet managed to eventually break out through the cocoon, but we haven’t seen any evidence for this yet. It is more likely that it got trapped and snuffed out by the cocoon.”

    The possibility that a cocoon was involved in the August 17 event was originally proposed in a study led by Caltech’s Mansi Kasliwal (MS ’07, PhD ’11), assistant professor of astronomy, and colleagues. She and her team from the NSF-funded Global Relay of Observatories Watching Transients Happen (GROWTH) project observed the event at multiple wavelengths using many different telescopes.

    “The cocoon model explains puzzling features we have observed in the neutron star merger,” says Kasliwal. “It fits observations across the electromagnetic spectrum, from the early blue light we witnessed to the radio waves and X-rays that turned on later. The cocoon model had predicted that the radio emission would continue to increase in brightness, and that’s exactly what we see.”

    The researchers say that future observations with LIGO, Virgo, and other telescopes will help further clarify the origins and mechanisms of these extreme events. The observatories should be able to detect additional neutron star mergers—and perhaps eventually, mergers of neutron stars and black holes.

    Work at Caltech on this study was funded by the NSF, the Sloan Research Foundation, and Research Corporation for Science Advancement. Other Caltech authors are Kishalay De, a graduate student, and Shri Kulkarni, George Ellery Hale Professor of Astronomy and Planetary Science.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    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.”

    Caltech campus

     
  • richardmitnick 4:06 pm on December 4, 2017 Permalink | Reply
    Tags: A New Spin to Solving Mystery of Stellar Companions, Are these planetary-mass companions actually planets or are they instead small "failed" stars called brown dwarfs?, , , , Caltech, , , , These new spin measurements suggest that if these bodies are massive planets located far away from their stars they have properties that are very similar to those of the smallest brown dwarfs   

    From Keck: “A New Spin to Solving Mystery of Stellar Companions” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    December 4, 2017
    Mari-Ela Chock, Keck Observatory
    (808) 554-0567
    mchock@keck.hawaii.edu

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

    1
    Credit: Gauza, B. et al 2015, MNRAS, 452, 1677-1683
    Image of the planetary-mass companion VHS 1256-1257 b (bottom right) and its host star (center).

    2
    Credit: Ireland, M. J. et al 2011, ApJ, 726, 113
    Image of the planetary-mass companion GSC 6214-210 b (bottom) and its host star (top).

    3
    Credit: Kraus, A. L. et al. 2014, ApJ, 781, 20
    Image of the planetary-mass companion ROXs 42B b (right, labeled ‘b’) and its host star (left, labeled ‘A’).

    Researchers Measure the Spin Rates of Bodies Thought to be Either Planets or Tiny “Failed” Stars.

    Taking a picture of an exoplanet—a planet in a solar system beyond our sun—is no easy task. The light of a planet’s parent star far outshines the light from the planet itself, making the planet difficult to see. While taking a picture of a small rocky planet like Earth is still not feasible, researchers have made strides by snapping images of about 20 giant planet-like bodies. These objects, known as planetary-mass companions, are more massive than Jupiter, orbit far from the glare of their stars, and are young enough to still glow with heat from their formation—all traits that make them easier to photograph.

    But one big question remains: Are these planetary-mass companions actually planets, or are they instead small “failed” stars called brown dwarfs? Brown dwarfs form like stars do—out of collapsing clouds of gas—but they lack the mass to ignite and shine with starlight. They can be found floating on the their own in space, or they can be found orbiting with other brown dwarfs or stars. The smallest brown dwarfs are similar in size to Jupiter and would look just like a planet when orbiting a star.

    Using the W. M. Keck Observatory on Maunakea, Hawaii, researchers at Caltech have taken a new approach to the mystery: they have measured the spin rates of three of the photographed planetary-mass companions and compared them to spin rates for small brown dwarfs. The results offer a new set of clues that hint at how the companions may have formed.

    “These companions with their high masses and wide separations could have formed either as planets or brown dwarfs,” says graduate student Marta Bryan (MS ’14), lead author of a new study describing the findings in the journal Nature Astronomy . “In this study, we wanted to shed light on their origins.”

    “These new spin measurements suggest that if these bodies are massive planets located far away from their stars, they have properties that are very similar to those of the smallest brown dwarfs,” says Heather Knutson, professor of planetary science at Caltech and a co-author of the paper.

    The astronomers measured the spin rate, or the length of a day, of three planetary-mass companions known as ROXs 42B b, GSC 6214-210 b, and VHS 1256-1257 b. They used an instrument at Keck Observatory called the Near Infrared Spectrograph (NIRSpec) to dissect the light coming from the companions.

    4
    Keck NIRSpec schematic

    As the objects spin on their axes, light from the side that is turning toward us shifts to shorter, bluer wavelengths, while light from the receding side shifts to longer, redder wavelengths. The degree of this shifting indicates the speed of a rotating body. The results showed that the three companions’ spin rates ranged between six to 14 kilometers per second, similar to rotation rates of our solar system’s gas giant planets Saturn and Jupiter.

    For the study, the researchers also included the two planetary-mass companions for which spin rates had already been measured. One, β Pictoris b, has a rotation rate of 25 kilometers per second—the fastest rotation rate of any planetary-mass body measured so far.

    The researchers compared the spin rates for the five companions to those measured previously for small free-floating brown dwarfs. The ranges of rotation rates for the two populations were indistinguishable. In other words, the companions are whirling about their own axes at about the same speeds as their free-floating brown-dwarf counterparts.

    The results suggest two possibilities. One is that the planetary-mass companions are actually brown dwarfs. The second possibility is that the companions looked at in this study are planets that formed, just as planets do, out of disks of material swirling around their stars, but for reasons not yet understood, the objects ended up with spin rates similar to those of brown dwarfs. Some researchers think that both newly forming planets and brown dwarfs are encircled by miniature gas disks that might be helping to slow their spin rates. In other words, similar physical processes may leave planets and brown dwarfs with similar spin rates.

    “It’s a question of nature versus nurture,” says Knutson. “Were the planetary companions born like brown dwarfs, or did they just end up behaving like them with similar spins?”

    The team also says that the companions are spinning more slowly than expected. Growing planets tend to be spun up by the material they pull in from a surrounding gas disk, in the same way that spinning ice skaters increase their speed, or angular momentum, when they pull their arms in. The relatively slow rotation rates observed for these objects indicate that they were able to effectively put the brakes on this spin-up process, perhaps by transferring some of this angular momentum back to encircling gas disks. The researchers are planning future studies of spin rates to further investigate the matter.

    “Spin rates of planetary-mass bodies outside our solar system have not been fully explored,” says Bryan. “We are just now beginning to use this as a tool for understanding formation histories of planetary-mass objects.”

    See the full article here .

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    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometer and world-leading laser guide star adaptive optics systems. Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.


    Keck UCal

     
  • richardmitnick 3:37 pm on November 14, 2017 Permalink | Reply
    Tags: , , , Caltech, , Samuel Oschin Telescope at Palomar Observatory, Zwicky Transient Facility Opens Its Eyes to the Volatile Cosmos   

    From Caltech: “Zwicky Transient Facility Opens Its Eyes to the Volatile Cosmos” 

    Caltech Logo

    Caltech

    11/14/2017

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

    1
    ZTF took this “first-light” image on Nov. 1, 2017, after being installed at the 48-inch Samuel Oschin Telescope at Palomar Observatory. The full-resolution version is more than 24,000 pixels by 24,000 pixels. Each ZTF image covers a sky area equal to 247 full moons. The Orion nebula is at lower right. Computers searching these images for transient, or variable, events are trained to automatically recognize and ignore non-astronomical sources, such as the vertical “blooming” lines seen here.
    Credit: Caltech Optical Observatories

    Caltech Palomar Samuel Oschin 48 inch Telescope Interior with Edwin Hubble

    Caltech Palomar Intermediate Palomar Transient Factory telescope at the Samuel Oschin Telescope at Palomar Observatory,located in San Diego County, California, United States

    2
    Fritz Zwicky at the 18-inch Schmidt telescope at Palomar Observatory in the 1930s.
    Credit: Edison R. Hoge Photograph Collection/Caltech Archives

    Zwicky Transit Facility schematic

    A new robotic camera with the ability to capture hundreds of thousands of stars and galaxies in a single shot has taken its first image of the sky, an event astronomers refer to as “first light.” The recently installed camera is part of a new automated sky-survey project called the Zwicky Transient Facility (ZTF), based at Caltech’s Palomar Observatory located in the mountains near San Diego. Every night, ZTF will scan a large portion of the Northern sky, discovering objects that erupt or vary in brightness, including exploding stars (also known as supernovas), stars being munched on by black holes, and asteroids and comets.

    “There’s a lot of activity happening in our night skies,” says Shrinivas (“Shri”) Kulkarni, the principal investigator of ZTF and the George Ellery Hale Professor of Astronomy and Planetary Science at Caltech. “In fact, every second, somewhere in the universe, there’s a supernova that’s exploding. Of course, we can’t see them all, but with ZTF we will see up to tens of thousands of explosive transients every year over the three-year lifetime of the project.”

    From 2009 to 2017, ZTF’s predecessor, the Palomar Transient Factory, caught the blinking, flaring, and other real-time changes of transient objects in the sky. The project took advantage of the fact that Palomar has three telescopes—the 48-inch Samuel Oschin Telescope, the 60-inch telescope and the 200-inch Hale Telescope—all under the management of Caltech. During the Palomar Transient Factory’s surveys, the automated Samuel Oschin Telescope acted as the discovery engine, with the automated 60-inch following up on any targets found and gleaning information about their identities. From there, astronomers would use the larger 200-inch Hale Telescope—or the W. M. Keck Observatory, which is co-managed by Caltech—to study in detail the various cosmic characters that enliven our night skies.

    “Going from one telescope to the next allowed us to perform a sort of triage and pick out the most interesting objects for further study; it was a vertically integrated observatory,” says Kulkarni. “The reason we called it the Palomar Transient Factory is because it did astronomy on an industrial scale.”


    Credit: Caltech

    The Zwicky Transient Facility is the powerful sequel to the Palomar Transient Factory. The name Zwicky refers to the first astrophysicist at Caltech, Fritz Zwicky, who arrived at the university in 1925 and who would go on to discover 120 supernovas over his lifetime. ZTF’s new state-of-the-art survey camera, recently installed at the Samuel Oschin Telescope, can see 47 square degrees of sky at a time, or the equivalent sky area of 247 full moons. That’s seven times more sky than its predecessor could see in a single image. What’s more, ZTF’s upgraded electronics and telescope-drive systems enable the camera to take 2.5 times as many exposures each night. ZTF will scan the entire sky over three nights and the visible plane of the galaxy twice every night.

    By scanning the sky so much faster, astronomers will discover not only a greater number of transient objects but also will be able to pick up the more fleeting events, those that appear and fade quickly.

    “ZTF will be faster than its predecessor because each image probes a wider swath of sky out to greater distances,” says Richard Dekany, the project manager for ZTF at Caltech. “Each image the camera takes is more than 24,000 by 24,000 pixels.”

    The images are so huge that they are hard to display on computer screens at full resolution. Roger Smith, the team’s technical lead at Caltech, has calculated that it would take 72 ultra-high-definition monitors to display one of ZTF’s images at full resolution. “I’d like to build that so we can really see the glory of ZTF’s full resolution,” says Smith, who has been working on the project along with Dekany, Kulkarni, and many others since it received funding from the National Science Foundation (NSF) in 2014.

    About half of ZTF is funded by the NSF; the rest comes from its partners, including the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland at College Park, the University of Washington, the Deutsches Elektronen-Synchrotron, Humboldt University, Los Alamos National Laboratory, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratory.

    ZTF images will be adjusted, cleaned, and calibrated at Caltech’s astronomy and data center known as IPAC. IPAC software will search the flood of data generated by ZTF for light sources, in particular those that change or move. These data will be made public to the entire astronomy community.

    “The data archive will grow by 4 terabytes of data each night,” says George Helou, the executive director of IPAC and a co-investigator on the NSF grant. “This is a unique project promising new types of discoveries.”

    Other NSF co-investigators include Caltech’s Tom Prince, the Ira S. Bowen Professor of Physics, and Bryan Penprase, dean of faculty at Soka University of America. ZTF’s project scientist is Matthew Graham of Caltech.

    Smith says that designing and building ZTF to capture such large images was particularly challenging given that the camera itself has to fit into a relatively small 70-year-old telescope tube. “The camera obstructs the light passing through the telescope toward the primary mirror, so we had to keep its size down while also maximizing the amount of sky it can observe,” he says.

    ZTF’s new first-light image is a taste of what’s to come. It showcases the large scale of the images and highlights the turbulent star-forming nebula known as Orion.

    Astronomers are excited for the unexpected findings to come. One of the Palomar Transient Factory’s biggest discoveries came in 2011 when it caught a supernova, named SN 2011fe, just hours after it had exploded. ZTF will further expand our knowledge of young supernovas along with a host of other cosmic objects, including planets around young stars, exotic binary star systems, and near-Earth asteroids.

    “ZTF will survey the dynamic universe unlike ever before,” says Mansi Kasliwal, assistant professor of astronomy at Caltech and a member of the ZTF team. “With its immense survey speed, ZTF can look at moving objects in the solar system, such as near-Earth asteroids, as well as cataclysmic eruptions of stars flickering in our own Milky Way galaxy. ZTF will find supernova explosions in faraway galaxies and even find electromagnetic counterparts to gravitational-wave sources detected by LIGO. It’s going to give us a treasure trove of discoveries.” Kasliwal notes that the gravitational-wave counterparts, once identified using ZTF, can be studied in detail using the Global Relay of Observatories Watching Transients Happen (GROWTH) project, led by Kasliwal.

    In the future, even larger surveys will build on ZTF’s rapid scans of the sky; these surveys include the upcoming Large Synoptic Survey Telescope (LSST), scheduled to be operational in 2023.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    “ZTF will be 10 times faster than the Palomar Transient Factory, while the upcoming LSST will be 10 times faster than ZTF,” says Kulkarni. “ZTF is a step toward the future.”

    ZTF’s science survey phase is scheduled to begin in February of 2018. The project will be completed by the end of 2020.

    See the full article here .

    Please help promote STEM in your local schools.

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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 11:50 am on November 1, 2017 Permalink | Reply
    Tags: Caltech, Excited states, Neural nets, , Quantum annealer,   

    From Caltech: “Physics Boosts Artificial Intelligence Methods” 

    Caltech Logo

    Caltech

    10/18/2017
    Contact
    Whitney Clavin
    (626) 395-1856
    wclavin@caltech.edu

    Written by Mark H. Kim

    1
    Higgs “di-photon” event candidate from Large Hadron Collider data collisions overlaid with a schematic of a wafer of quantum processors.
    Credit: LHC Image: CERN/CMS Experiment; Composite: M. Spiropulu (Caltech)

    Researchers from Caltech and the University of Southern California (USC) report the first application of quantum computing to a physics problem. By employing quantum-compatible machine learning techniques, they developed a method of extracting a rare Higgs boson signal from copious noise data. Higgs is the particle that was predicted to imbue elementary particles with mass and was discovered at the Large Hadron Collider in 2012. The new quantum machine learning method is found to perform well even with small datasets, unlike the standard counterparts.

    Despite the central role of physics in quantum computing, until now, no problem of interest for physics researchers has been resolved by quantum computing techniques. In this new work, the researchers successfully extracted meaningful information about Higgs particles by programming a quantum annealer—a type of quantum computer capable of only running optimization tasks—to sort through particle-measurement data littered with errors. Caltech’s Maria Spiropulu, the Shang-Yi Ch’en Professor of Physics, conceived the project and collaborated with Daniel Lidar, pioneer of the quantum machine learning methodology and Viterbi Professor of Engineering at USC who is also a Distinguished Moore Scholar in Caltech’s divisions of Physics, Mathematics and Astronomy and Engineering and Applied Science.

    The quantum program seeks patterns within a dataset to tell meaningful data from junk. It is expected to be useful for problems beyond high-energy physics. The details of the program as well as comparisons to existing techniques are detailed in a paper published on October 19 in the journal Nature.

    A popular computing technique for classifying data is the neural network method, known for its efficiency in extracting obscure patterns within a dataset. The patterns identified by neural networks are difficult to interpret, as the classification process does not reveal how they were discovered. Techniques that lead to better interpretability are often more error prone and less efficient.

    “Some people in high-energy physics are getting ahead of themselves about neural nets, but neural nets aren’t easily interpretable to a physicist,” says USC’s physics graduate student Joshua Job, co-author of the paper and guest student at Caltech. The new quantum program is “a simple machine learning model that achieves a result comparable to more complicated models without losing robustness or interpretability,” says Job.

    With prior techniques, the accuracy of classification depends strongly on the size and quality of a training set, which is a manually sorted portion of the dataset. This is problematic for high-energy physics research, which revolves around rare events buried in large amount of noise data. “The Large Hadron Collider generates a huge number of events, and the particle physicists have to look at small packets of data to figure out which are interesting,” says Job. The new quantum program “is simpler, takes very little training data, and could even be faster. We obtained that by including the excited states,” says Spiropulu.

    Excited states of a quantum system have excess energy that contributes to errors in the output. “Surprisingly, it was actually advantageous to use the excited states, the suboptimal solutions,” says Lidar.

    “Why exactly that’s the case, we can only speculate. But one reason might be that the real problem we have to solve is not precisely representable on the quantum annealer. Because of that, suboptimal solutions might be closer to the truth,” says Lidar.

    Modeling the problem in a way that a quantum annealer can understand proved to be a substantial challenge that was successfully tackled by Spiropulu’s former graduate student at Caltech, Alex Mott (PhD ’15), who is now at DeepMind. “Programming quantum computers is fundamentally different from programming classical computers. It’s like coding bits directly. The entire problem has to be encoded at once, and then it runs just once as programmed,” says Mott.

    Despite the improvements, the researchers do not assert that quantum annealers are superior. The ones currently available are simply “not big enough to even encode physics problems difficult enough to demonstrate any advantage,” says Spiropulu.

    “It’s because we’re comparing a thousand qubits—quantum bits of information—to a billion transistors,” says Jean-Roch Vlimant, a postdoctoral scholar in high energy physics at Caltech. “The complexity of simulated annealing will explode at some point, and we hope that quantum annealing will also offer speedup,” says Vlimant.

    The researchers are actively seeking further applications of the new quantum-annealing classification technique. “We were able to demonstrate a very similar result in a completely different application domain by applying the same methodology to a problem in computational biology,” says Lidar. “There is another project on particle-tracking improvements using such methods, and we’re looking for new ways to examine charged particles,” says Vlimant.

    “The result of this work is a physics-based approach to machine learning that could benefit a broad spectrum of science and other applications,” says Spiropulu. “There is a lot of exciting work and discoveries to be made in this emergent cross-disciplinary arena of science and technology, she concludes.

    This project was supported by the United States Department of Energy, Office of High Energy Physics, Research Technology, Computational HEP; and Fermi National Accelerator Laboratory as well as the National Science Foundation. The work was also supported by the AT&T Foundry Innovation Centers through INQNET (INtelligent Quantum NEtworks and Technologies), a program for accelerating quantum technologies.

    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 5:20 am on October 25, 2017 Permalink | Reply
    Tags: , , , Caltech, , , , ,   

    Science Magazine: NASA weighs trimming WFIRST to hold down costs 

    ScienceMag
    Science Magazine

    1
    The proposed Wide Field Infrared Survey Telescope. NASA

    Oct. 23, 2017
    Daniel Clery

    NASA will have to scale back its next big orbiting observatory to avoid busting its budget and affecting other missions, an independent panel says. The Wide Field Infrared Survey Telescope (WFIRST) is due for launch in the mid-2020s. But 1 year after NASA gave the greenlight its projected cost is $3.6 billion, roughly 12% overbudget.

    “I believe reductions in scope and complexity are needed,” Thomas Zurbuchen, head of NASA’s Science Mission Directorate in Washington, D.C., wrote in a memo that NASA released last Thursday.

    Designed to investigate the nature of dark energy and study exoplanets, WFIRST was chosen by the astronomy community as its top space-based mission priority in the 2010 decadal survey entitled New Worlds, New Horizons in Astronomy and Astrophysics. But the start of the project was initially delayed by the huge overspend on its predecessor, the James Webb Space Telescope, which will be launched in 2019.

    NASA/ESA/CSA Webb Telescope annotated

    Then last year, a midterm review of the 2010 decadal survey warned that WFIRST could go the same way and advised NASA to form a panel of independent experts to review the project.

    NASA assembled that panel in April this year and it recently submitted its conclusions. The agency has not released its report, as it is due to be discussed by the Committee for Astronomy and Astrophysics of the National Academies of Sciences, Engineering, and Medicine this week, but it did release a memo from Zurbuchen to Christopher Scolese, director of the Goddard Space Flight Center in Greenbelt, Maryland, which is leading the project.

    In it, Zurbuchen directs the lab “to study modifying the current WFIRST design … to reduce cost and complexity sufficient to have a cost estimate consistent with the $3.2 billion cost target [set last year].” Though the panel heaped praise on the WFIRST team for the work done so far, according to Zurbuchen’s memo, it faulted NASA managers for creating several challenges that have made the project “more complicated than originally anticipated.”

    Paul Hertz, head of NASA’s astrophysics division, told ScienceInsider that one major demand was enlarging the spacecraft to accommodate a 2.4-meter mirror that the National Reconnaissance Office donated in 2012. Another was adding an instrument called a coronagraph.

    WFIRST, which will have the sensitivity of the Hubble Space Telescope but with 100 times its field of view, was originally designed to survey the sky for signs of cosmic acceleration caused by dark energy. But when exoplanet researchers realized it would also benefit their field they lobbied for the inclusion of a coronagraph. This device acts as a mask inside the telescope to block out the glaring brightness of a star and reveal any dim planets around it.

    NASA also decided to split the ground segment for the mission between the Space Telescope Science Institute in Baltimore, Maryland, and the California Institute of Technology in Pasadena.

    And in an act of future-proofing, NASA wanted WFIRST to carry equipment making it compatible with a starshade, a proposed spacecraft that can be stationed at a distance to block out starlight and reveal exoplanets (more effectively than a coronagraph). “All these things added complexity,” Hertz says.

    1
    Starshade. NASA

    Zurbuchen’s memo to Scolese directs the lab to retain the basic elements of the mission—the 2.4-meter mirror, widefield camera, and coronagraph—but to seek cost-saving “reductions.” Hertz says this will require reducing the capabilities of instruments but ensuring they remain “above the science floor laid down by the decadal survey.” The coronagraph will be recategorized as a “technology demonstration instrument,” removing the burden of achieving a scientific target. The change will also save money, Hertz explains.

    Hertz says exoplanet researchers shouldn’t worry about the proposed changes. “We know we’ll get good science out of the coronagraph. We’ll be able to see debris disks, zodiacal dust, and exoplanets in wide orbits,” he says. Astronomers wanting to see Earth twins in the habitable zone may be disappointed, however.

    Zurbuchen also asked project managers to save money in the ground segment and by letting industry build some components or subsystems. The WFIRST team will need to submit a revised design by February 2018, before vendors are chosen, to begin building the hardware.

    If costs continue to escalate, Zurbuchen says in his memo, NASA may need to abandon the 2.4-meter mirror and revert to the original, cheaper design using a 1.5-meter one. “That is plan B,” says Hertz, “but we very much like the 2.4-meter mirror.”

    See the full article here .

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  • richardmitnick 9:34 pm on October 16, 2017 Permalink | Reply
    Tags: , , , Caltech, , GROWTH, Mansi Kasliwal (PhD '11),   

    From Caltech: Women in STEM – “Star Sleuth: Mansi Kasliwal (PhD ’11)” 

    Caltech Logo

    Caltech

    Fall 2017, Features
    A Caltech astronomer combs the night sky for clues about the fates of stars.

    1
    Mansi Kasliwal. Photo: Mario de Lopez

    Mansi Kasliwal, an assistant professor of astronomy at Caltech, searches the night sky for astronomical transients—the flashes of light that appear when a star becomes a million to a billion times as bright as our sun and then quickly fades away. As principal investigator of GROWTH (Global Relay of Observatories Watching Transients Happen), she heads up a worldwide network of collaborators who are trying to capture the details of these transient events to find out more about how they evolved.

    Kasliwal grew up in Indore, India, and came to the United States to study at the age of 15. She earned her BS at Cornell University and then came to Caltech to complete her doctoral work in astronomy. After a postdoctoral fellowship at Pasadena’s Carnegie Observatories, she joined the Caltech faculty in 2015.

    We talked with Kasliwal about her fascination with the night sky, why she doesn’t mind 3 a.m. phone calls, and the dream she hopes will take her to the South Pole.

    Caltech Magazine: What is the main focus of your research?

    Mansi Kasliwal: It’s basically about discovering and understanding transients—the energetic flashes of light that cause the fireworks that adorn the night sky—and what they can tell us about the elements and where they are synthesized, the fates of stars, and what happens in the final stages of their lives.

    There are two main themes to my research: One has to do with optical transients, or transients that can be seen with optical telescopes—that’s where GROWTH comes in—and the other is around infrared transients and exploring the dynamic infrared sky.

    CM: Let’s start with GROWTH.

    MK: I’ve done optical astronomy for my entire career here. GROWTH builds off of that. GROWTH is primarily looking at optical transients from a host of different observatories to build a more complete picture of the physical processes of their evolution. We have a network of 18 observatories in the Northern Hemisphere. As Earth rotates and daylight creeps in at one of our locations, we switch observations to one of our facilities westward that is still enjoying nighttime.

    CM: How do you communicate with one another when one of the observatories sees an intriguing transient in the night sky?

    MK: Some alerts are fully robotic, i.e., my computer calls me. Some alerts are from my collaborators on the other side of the globe. The best part about GROWTH is that even if a phone call is at 3 a.m., everyone’s sleepy voices are actually quite excited.

    CM: A new system of telescopes is coming online at Caltech’s Palomar Observatory in Southern California called the Zwicky Transient Facility (ZTF). What makes it better than the Palomar Transient Factory that was there before?

    Caltech Palomar Observatory, located in San Diego County, California, US, at 1,712 m (5,617 ft)

    MK: ZTF is an order of magnitude faster in survey speed, so we can either search more sky or we can search the sky faster or we can go deeper. This will help us find many more rare, fast, and young transients. ZTF is a fantastic new discovery engine providing targets for the GROWTH network.

    CM: I know GROWTH is looking for baby supernovas, among other things. Why is that important?

    MK: Supernovas shine for months. But what happens in the first 24 hours after explosion, when the supernova is in its infancy, is critical. The initial flash of light immediately interacts with the surrounding material and tells us what that pristine material was before the supernova exploded. Then, there’s a 10,000-kilometers-per-second blast wave that sweeps it all up. When we study the ultraviolet light and the spectroscopic signatures with the GROWTH network, within the first 24 hours, we can get a glimpse into what type of star exploded.

    CM: You’re also searching for what you call the “cosmic mines,” the heavy elements in the periodic table, which come from extreme gravitational events. Tell me how you work with Advanced LIGO [the Laser Interferometer Gravitational-wave Observatory] on this?


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    MK: As soon as the LIGO researchers think they have detected a gravitational wave, they tell me roughly which part of the sky it’s in, and we drop everything we’re doing and go and search this large area of the sky for any flashes of light that could be physically associated with that signal.

    What we’re hoping for is at least one neutron star in the merger that LIGO saw. If a neutron star smashes into a black hole or into another neutron star, then there will be light. A neutron star can feed the formation of these very heavy elements, like gold, platinum, and uranium. When these elements decay radioactively, that gives you photons.

    2
    In 2002, a star called V838 Mon became the brightest star in the Milky Way. This image, taken with the Hubble Space Telescope, reveals the so called light echo—the flash of light reflected from layers of dust surrounding the star. Photo: NASA, ESA

    So when we get notification of a new gravitational-wave signal, we search the sky for flashes and rack our brains about which ones are completely unrelated, which ones are in the foreground, which ones are in the background, and which one—just one, if any, out of all of them—is the real thing. It is a very complicated process of sifting through a large volume of data in a very short timescale, because we only have 24 hours before the flash, if there is one, fades away.

    So far, every time we’ve done this, it turned out to be two black holes that were merging, and we found nothing because black holes are very black. They generally don’t produce the electromagnetic light we are looking for. But it’s all good preparation for when LIGO finds something with one or two neutron stars.

    This work with LIGO ties together my two loves in my professional life, the optical and the infrared, because the signal that is expected from such a violent merger—one that should produce all these sparkling, heavy elements—has two components. One is a fast-fading optical blue component, which is what the GROWTH network is designed to pick up, and the other is a more slowly evolving infrared component. Unfortunately, no one has a wide-field infrared telescope yet.

    CM: So exploring the infrared night sky is the new area you’re developing now?

    MK: Yes, this is the new project that I’m doing, which is something that just didn’t even exist as a field a few years ago because the infrared is a very hard waveband to probe. The night sky is very bright, and detectors are very expensive. There are a lot of practical reasons astronomers have shied away from exploring the dynamic infrared night sky.

    But just in the last few years, we’ve made some progress. I’m doing a project called SPIRITS. This is the SPitzer InfraRed Intensive Transients Survey. It’s a large program of the Spitzer Space Telescope.

    NASA/Spitzer Infrared Telescope

    3
    An artist’s impression of a white dwarf “stealing” matter from a companion star. Photo: David A. Hardy

    We are looking at 200 galaxies over and over again to see if there are any new flashes of light in the infrared wave-bands. The cool thing here—quite literally cool—is that the search found a class of transients that were so cold they were completely missed in optical and other wave-bands. We think that some of these could be the result of the mergers of two stars, or they could be the birth of massive star binaries in which you have a shock that gets driven out. That shock excites the surrounding medium in the infrared wavebands and lights it up. We don’t know what those transients are, so we just gave them a name. The project was SPIRITS, so we call them SPRITEs.

    Now I’m taking this to the next level. At Palomar Observatory, I’m putting together a 25-square-degree infrared camera that will be able to cover the entire night sky in one night. I hope to commission it in November. If that goes well, and I’m able to prove the technology there, then I want to go to the cold and dark South Pole to do a really nice systematic search of the night sky for infrared transients.

    CM: What is it like being back at Caltech as a professor when you were here as a doctoral student just a few years ago?

    MK: Caltech is certainly a dream job for me, and it was sort of like coming back home. Caltech has the kind of students that I know are all awesome. The grad students at Caltech were my friends, and I’ve seen what they can do. So I knew that, being a faculty member, I would have the privilege of working with students who are not only brilliant but also have an amazing attitude.

    CM: Are you down at Palomar Observatory frequently?

    MK: Yes, and I’m always excited about working with Caltech’s Palomar and Keck observatories.


    Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft) above sea level

    I know the telescopes well, what to do with them. Also, I’ve known the engineers and the staff there for many years, and I’ve had a really great relationship with them. It’s really fun to work with the staff. They’re very dedicated. They revel in the joy of discovery.

    CM: You’ve been in the U.S. now for longer than you lived in India. Do you get back there regularly?

    MK: My parents live in India, so we go back once a year. Also, I have two GROWTH co-investigators in India. In fact, one is a Caltech alum who is now a faculty member at the prestigious Indian Institute of Technology in Mumbai. His students come here for internships; I send students to him for internships. This is wonderful in terms of the collaboration.
    Bringing astronomy at the cutting edge to India, with this privileged access and opportunity I have here at Caltech, to share that with my colleagues in India … it’s really fun.

    CM: And last, but certainly not least, you also have a young child.

    MK: I have a two-year-old son. His name is Vyom. That means “the universe” in Sanskrit. I have a little baby universe who is the joy of my life.

    See the full article here .

    Please help promote STEM in your local schools.

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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 12:35 pm on September 11, 2017 Permalink | Reply
    Tags: Caltech, First On-chip Nanoscale Optical Quantum Memory Developed, ,   

    From Caltech: “First On-chip Nanoscale Optical Quantum Memory Developed” 

    Caltech Logo

    Caltech

    09/11/2017

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

    1
    Artist’s representation of Faraon’s quantum memory device. Credit: Ella Maru Studio

    Smallest-yet optical quantum memory device is a storage medium for optical quantum networks with the potential to be scaled up for commercial use.

    For the first time, an international team led by engineers at Caltech has developed a computer chip with nanoscale optical quantum memory.

    Quantum memory stores information in a similar fashion to the way traditional computer memory does, but on individual quantum particles—in this case, photons of light. This allows it to take advantage of the peculiar features of quantum mechanics (such as superposition, in which a quantum element can exist in two distinct states simultaneously) to store data more efficiently and securely.

    “Such a device is an essential component for the future development of optical quantum networks that could be used to transmit quantum information,” says Andrei Faraon (BS ’04), assistant professor of applied physics and materials science in the Division of Engineering and Applied Science at Caltech, and the corresponding author of a paper describing the new chip.

    The study appeared online ahead of publication by Science magazine on August 31.

    “This technology not only leads to extreme miniaturization of quantum memory devices, it also enables better control of the interactions between individual photons and atoms,” says Tian Zhong, lead author of the study and a Caltech postdoctoral scholar. Zhong is also an acting assistant professor of molecular engineering at the University of Chicago, where he will set up a laboratory to develop quantum photonic technologies in March 2018.

    The use of individual photons to store and transmit data has long been a goal of engineers and physicists because of their potential to carry information reliably and securely. Because photons lack charge and mass, they can be transmitted across a fiber optic network with minimal interactions with other particles.

    The new quantum memory chip is analogous to a traditional memory chip in a computer. Both store information in a binary code. With traditional memory, information is stored by flipping billions of tiny electronic switches either on or off, representing either a 1 or a 0. That 1 or 0 is known as a bit. By contrast, quantum memory stores information via the quantum properties of individual elementary particles (in this case, a light particle). A fundamental characteristic of those quantum properties—which include polarization and orbital angular momentum—is that they can exist in multiple states at the same time. This means that a quantum bit (known as a qubit) can represent a 1 and a 0 at the same time.

    To store photons, Faraon’s team created memory modules using optical cavities made from crystals doped with rare-earth ions. Each memory module is like a miniature racetrack, measuring just 700 nanometers wide by 15 microns long—on the scale of a red blood cell. Each module was cooled to about 0.5 Kelvin—just above Absolute Zero (0 Kelvin, or -273.15 Celsius)—and then a heavily filtered laser pumped single photons into the modules. Each photon was absorbed efficiently by the rare-earth ions with the help of the cavity.

    The photons were released 75 nanoseconds later, and checked to see whether they had faithfully retained the information recorded on them. Ninety-seven percent of the time, they had, Faraon says.

    Next, the team plans to extend the time that the memory can store information, as well as its efficiency. To create a viable quantum network that sends information over hundreds of kilometers, the memory will need to accurately store data for at least one millisecond. The team also plans to work on ways to integrate the quantum memory into more complex circuits, taking the first steps toward deploying this technology in quantum networks.

    The study is titled “Nanophotonic rare-earth quantum memory with optically controlled retrieval.” Other Caltech coauthors include postdoctoral researcher John G. Bartholomew; graduate students Jonathan M. Kindem (MS ’17), Jake Rochman, and Ioana Craiciu (MS ’17); and former graduate student Evan Miyazono (MS ’15, PhD ’17). Additional authors are from the University of Verona in Italy; the University of Parma in Italy; the National Institute of Standards and Technology in Colorado; and the Jet Propulsion Laboratory, which is managed for NASA by Caltech. This research was funded by the National Science Foundation, the Air Force Office of Scientific Research, and the Defense Advanced Research Projects Agency.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.”

    Caltech campus

     
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