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  • richardmitnick 2:22 pm on January 17, 2017 Permalink | Reply
    Tags: , Basic Research, , Habitable zones, SF State,   

    From SF State: “SF State astronomer searches for signs of life on Wolf 1061 exoplanet” 

    SFSU bloc

    San Fransisco State University

    January 13, 2017
    Jamie Oppenheim

    1
    An artist’s rendering of an exoplanet is shown. An exoplanet is a planet that exists outside Earth’s solar system. Illustration credit: NASA/Ames/JPL-Caltech

    SF State astronomer Stephen Kane searches for signs of life in one of the extrasolar systems closest to Earth.

    Is there anybody out there? The question of whether Earthlings are alone in the universe has puzzled everyone from biologists and physicists to philosophers and filmmakers. It’s also the driving force behind San Francisco State University astronomer Stephen Kane’s research into exoplanets — planets that exist outside Earth’s solar system.

    As one of the world’s leading “planet hunters,” Kane focuses on finding “habitable zones,” areas where water could exist in a liquid state on a planet’s surface if there’s sufficient atmospheric pressure. Kane and his team, including former undergraduate student Miranda Waters, examined the habitable zone on a planetary system 14 light years away. Their findings will appear in the next issue of Astrophysical Journal in a paper titled Characterization of the Wolf 1061 Planetary System.

    “The Wolf 1061 system is important because it is so close and that gives other opportunities to do follow-up studies to see if it does indeed have life,” Kane said.

    But it’s not just Wolf 1061’s proximity to Earth that made it an attractive subject for Kane and his team. One of the three known planets in the system, a rocky planet called Wolf 1061c, is entirely within the habitable zone. With assistance from collaborators at Tennessee State University and in Geneva, Switzerland, they were able to measure the star around which the planet orbits to gain a clearer picture of whether life could exist there.

    When scientists search for planets that could sustain life, they are basically looking for a planet with nearly identical properties to Earth, Kane said. Like Earth, the planet would have to exist in a sweet spot often referred to as the “Goldilocks zone” where conditions are just right for life. Simply put, the planet can’t be too close or too far from its parent star. A planet that’s too close would be too hot. If it’s too far, it may be too cold and any water would freeze, which is what happens on Mars, Kane added.

    Conversely, when planets warm, a “runaway greenhouse effect” can occur where heat gets trapped in the atmosphere. Scientists believe this is what happened on Earth’s twin, Venus. Scientists believe Venus once had oceans, but because of its proximity to the sun the planet became so hot that all the water evaporated, according to NASA. Since water vapor is extremely effective in trapping in heat, it made the surface of the planet even hotter. The surface temperature on Venus now reaches a scalding 880 degrees Fahrenheit.

    Since Wolf 1061c is close to the inner edge of the habitable zone, meaning closer to the star, it could be that the planet has an atmosphere that’s more similar to Venus. “It’s close enough to the star where it’s looking suspiciously like a runaway greenhouse,” Kane said.

    Kane and his team also observed that unlike Earth, which experiences climatic changes such as an ice age because of slow variations in its orbit around the sun, Wolf 1061c’s orbit changes at a much faster rate, which could mean the climate there could be quite chaotic. “It could cause the frequency of the planet freezing over or heating up to be quite severe,” Kane said.

    These findings all beg the question: Is life possible on Wolf 1061c? One possibility is that the short time scales over which Wolf 1061c’s orbit changes could be enough that it could actually cool the planet off, Kane said. But fully understanding what’s happening on the planet’s surface will take more research.

    In the coming years, there will be a launch of new telescopes like the James Webb Space Telescope, the successor to the Hubble Space Telescope, Kane said, and it will be able to detect atmospheric components of the exoplanets and show what’s happening on the surface.

    See the full article here .

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    SFSU Campus

    San Francisco State University (commonly referred to as San Francisco State, SF State and SFSU) is a public comprehensive university located in San Francisco, California, United States. As part of the 23-campus California State University system, the university offers 118 different Bachelor’s degrees, 94 Master’s degrees, 5 Doctoral degrees including two Doctor of Education, a Doctor of Physical Therapy, a Ph.D in Education and Doctor of Physical Therapy Science, along with 26 teaching credentials among six academic colleges.

     
  • richardmitnick 1:56 pm on January 17, 2017 Permalink | Reply
    Tags: , Basic Research, , The value of basic research   

    From Symmetry: “The value of basic research” 

    Symmetry Mag
    Symmetry

    01/17/17
    Leah Crane

    How can we measure the worth of scientific knowledge? Economic analysts give it a shot.

    Before building any large piece of infrastructure, potential investors or representatives from funding agencies or governments have to decide whether it’s worth it. Teams of economists perform a cost-benefit analysis to help them determine how a project will affect a region and whether it makes sense to back and build it.

    Superconducting Super Sollider map, in the vicinity of Waxahachie, Texas.
    Superconducting Super Collider map, in the vicinity of Waxahachie, Texas, cancelled by Congress in 1993 because there was “no immediate economic gain,” literally ceding the future of HEP to Europe at CERN.

    But when it comes to building infrastructure for basic science, the process gets a little more complicated. It’s not so easy to pin an exact value on the benefits of something like the Large Hadron Collider.

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    “The main goal is priceless and therefore has no price attached,” says Stefano Forte, a professor of theoretical physics at the University of Milan and part of a team that developed a new method of economic analysis for fundamental science. “We give no value to discovering the Higgs boson in the past or supersymmetry or extra dimensions in the future, because we wouldn’t be able to say what the value of the discovery of extra dimensions is.”

    Forte’s team was co-led by two economists, academic Massimo Florio, also of the University of Milan, and private business consultant Silvia Vignetti. They answered a 2012 call by the European Investment Bank’s University Sponsorship Program, which provides grants to university research centers, for assistance with this issue. The bank funded their research into a new way to evaluate proposed investments in science.

    Before anyone can start evaluating any sort of impact, they have to define what they’re measuring. Generally, economic impact analyses are highly local, measuring exclusively money flowing in and out of a particular area.

    Because of the complicated nature of financing any project, the biggest difficulty for economists performing an analysis is usually coming up with an appropriate counterfactual: If the project isn’t built, what will happen? [Obviously mot done y or Congress in 1993.] As Forte asks, “If you hadn’t spent the money there, where else would you have spent it, and are you sure that by spending it there rather than somewhere else you actually gain something?”

    Based on detailed information about where a scientific collaboration intends to spend their money, economists can take the first step in painting a picture of how that funding will affect the region. The next step is accounting for the secondary spending that this brings.

    Companies are paid to do construction work for a scientific project, “and then it sort of cascades throughout the region,” says Jason Horwitz of Anderson Economic Group, which regularly performs economic analyses for universities and physics collaborations. “As they hire more people, the employees themselves are probably going to local grocery stores, going to local restaurants, they might go to a movie now and then—there’s just more local spending.”

    These first parts of the analysis account only for the tangible, concrete-and-steel process of building and maintaining an experiment, though.

    “If you build a bridge, the main benefit is from people who use the build—transportation of goods over the bridge and whatnot,” Forte says. But the benefit of constructing a telescope array or a huge laser interferometer is knowledge-formation, “which is measured in papers and publications, references and so on,” he says.

    One way researchers like Horwitz and Forte have begun to assign value to such projects is by measuring the effect of the project on the people who run it. Like attending university, working on a scientific collaboration gives you an education—and an education changes your earning capabilities.

    “Fundamental research has a huge added value in terms of human capital formation, even if you work there for two years and then you go and work in a company on Wall Street,” Forte says. Using the same methods used by universities, they found doing research at the LHC would raise students’ earning potential by about 11 percent over a 40-year career.

    This method of measuring the value of scientific projects still has limitations. In it, the immeasurable, grander purpose of a fundamental science experiment is still assigned no value at all. When it comes down to it, Forte says, if all we cared about were a big construction project, technology spinoffs and the earning potential of students, we wouldn’t have fundamental physics research.

    “The actual purpose of this is not a big construction project,” Horwitz says. “It’s to do this great research which obviously has other benefits of its own, and we really don’t capture any of that.” Instead, his group appends qualitative explanations of the knowledge to be gained to their economic reports.

    Forte explains, “The fact that this kind of enterprise exists is comparable and evaluated in the same way as, say, the value of the panda not being extinct. If the panda is extinct, there is no one who’s actually going to lose money or make money—but many taxpayers would be willing to pay money for the panda not to be extinct.”

    Forte and his colleagues found a 90 percent chance of the LHC’s benefits exceeding its costs (by 2.9 billion euros, they estimate). But even in the 10 percent chance that its economics aren’t quite so Earth-shaking, its discoveries could change the way we understand our universe.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:41 pm on January 17, 2017 Permalink | Reply
    Tags: , Basic Research, , Gaia: The Stars in Motion   

    From astrobites: “Gaia: The Stars in Motion” 

    Astrobites bloc

    Astrobites

    Jan 17, 2017
    Philipp Plewa

    Title: First Gaia Local Group Dynamics: Magellanic Clouds Proper Motion And Rotation
    Authors: R. P. van der Marel & J. Sahlmann
    First Author’s Institution: Space Telescope Science Institute
    1
    Status: Published in The Astrophysical Journal Letters, open access

    Although the night sky seems unchanging, it is in constant motion. Stars are not stationary objects but move through space, just like the Sun is moving along an orbit around the center of the Milky Way. A consequence is that all of today’s well-known constellations will eventually become unrecognizable (after a few hundred thousand years).

    2
    Figure 1 The proper motion of a star is its apparent (angular) motion on the sky, which reflects the transverse component of its true motion (Figure from the RAVE collaboration).

    The apparent motions of individual stars on the sky are called proper motions (Fig. 1) and the study of such motions is part of a field called astrometry. A revolutionary satellite dedicated to precision astrometry, Hipparcos, was launched in 1989 and provided a comprehensive catalog of the motions of stars in the backyard of the Solar System, which grew to include 2.5 million stars. Its modern successor, Gaia, was launched in 2013 and will reveal the motions of about a billion stars in total.

    ESA/GAIA satellite
    ESA/GAIA satellite

    The authors of today’s paper focus on using Gaia to study the Large Magellanic Cloud (LMC).

    Large Magellanic Cloud. Adrian Pingstone  December 2003
    Large Magellanic Cloud. Adrian Pingstone December 2003

    The LMC is the most massive satellite galaxy orbiting the Milky Way, and a prominent feature in the southern night sky. In the latest Tycho-Gaia catalog, there are 29 stars that have been identified as likely members of the LMC. The typical proper motion of these bright young stars is about 1.8 mas (or 2 millionths of a degree) per year, which corresponds to an actual velocity of around 430 kilometers per second at the distance of the LMC (approximately 50.1 kpc, or 6 times the distance to the Galactic Center). The measurement precision of 0.15 mas/yr is extraordinary, considering that 0.1 mas on the sky is roughly the apparent size of a frisbee on the Moon.

    3
    Figure 2 The observed velocity pattern of stars in the Large Magellanic Cloud (yellow arrows) reveals a rotating disk structure. The bottom left inset shows the average velocity that has been subtracted, while the bottom right inset shows the typical measurement uncertainty. (Figure 1 in the paper.)

    he observed velocity pattern of the stars can be separated into a linear average motion and a clockwise peculiar motion (Fig. 2), which is evidence for a rotating disk structure. This rather large proper motion of the LMC and its internal rotation have already been found by previous studies (e.g. van der Marel & Kallivayalil 2014). It is testing the reproducibility of these results that is the authors’ main goal, as well as exploring the capabilities of Gaia. The authors have also performed essentially the same analysis on a completely independent data set obtained with yet another satellite, the Hubble Space Telescope. It is reassuring that the results indeed turn out consistent, which means that the underlying approaches are sound and that there are no lingering systematic uncertainties.

    The rotation curve inferred from the proper motion data also matches the line-of-sight (“radial”) velocities of other stars in the LMC. Taken together, these data sets can be used to estimate the distance to the LMC, based purely on observations of the stellar dynamics. Photometric methods, based on measuring the luminosities of stars (e.g. Freedman et al. 2001), yield more precise estimates (at least for now), but again two independent approaches lead to the same consistent result.

    Astrometry and the study of stellar motions in the LMC, the Milky Way and other stellar systems is critical in understanding their structure and history (see Lucia’s post on “The Fate of the Milky Way”). After the initial data release of the Gaia mission, this paper was one of the first to be submitted. And even though this data set is still limited, it immediately led to some new and exciting insights. All things considered, the wealth of high-quality data yet to be released certainly has the potential to revolutionize this field once again, starting in (fingers crossed) late 2017. Feel free continue reading Ben’s post on Gaia’s potential for finding exoplanets.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    What do we do?

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

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

     
  • richardmitnick 1:03 pm on January 17, 2017 Permalink | Reply
    Tags: , , Basic Research,   

    From ALMA: “ALMA Starts Observing the Sun” This is a Blast 

    ALMA Array

    ALMA

    17 January 2017
    Nicolás Lira T.
    Press Coordinator
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 24 67 65 19
    Cell: +56 9 94 45 77 26
    Email: nicolas.lira@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Masaaki Hiramatsu

    Education and Public Outreach Officer, NAOJ Chile
    Observatory
Tokyo, Japan

    Tel: +81 422 34 3630

    E-mail: hiramatsu.masaaki@nao.ac.jp

    1
    This image of the entire Sun was taken at a wavelength of 617.3 nm. Light at this wavelength originates from the visible solar surface, the photosphere. A cooler, darker sunspot is clearly visible in the disk, and — as a visual comparison — a depiction from ALMA at a wavelength of 1.25 millimeters is shown. Credit: ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AUI/NSF) | Full-disc solar image: Filtergram taken in Fe I 617.3 nm spectral line with the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). Credit: NASA

    NASA/SDO
    NASA/SDO

    New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal stunning details of our Sun, including the dark, contorted center of an evolving sunspot nearly twice as large as the diameter of the Earth. These images are part of the testing and verification campaign to make ALMA’s solar observing capabilities available to the international astronomical community.

    Though designed principally to observe remarkably faint objects throughout the Universe — such as distant galaxies and planet-forming disks around young stars – ALMA is also capable of studying objects in our own Solar System, including planets, comets, and now our own Sun.

    2
    This ALMA image of an enormous sunspot was taken on 18 December 2015 with the Band 6 receiver at a wavelength of 1.25 millimeters. Sunspots are transient features that occur in regions where the Sun’s magnetic field is extremely concentrated and powerful. They are lower in temperature than their surrounding regions, which is why they appear relatively dark in visible light. The ALMA image is essentially a map of temperature differences in a layer of the Sun’s atmosphere known as the chromosphere, which lies just above the visible surface of the Sun (the photosphere). The chromosphere is considerably hotter than the photosphere. Understanding the heating and dynamics of the chromosphere are key areas of research that will be addressed by ALMA. Observations at shorter wavelengths probe deeper into the solar chromosphere than longer wavelengths. Hence, Band 6 observations map a layer of the chromosphere that is closer to the visible surface of the Sun than Band 3 observations. Credit: ALMA (ESO/NAOJ/NRAO)

    During a 30-month period beginning in 2014, an international team of astronomers harnessed ALMA’s single-antenna and array capabilities to detect and image the millimeter-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, the visible surface of the Sun.

    4
    ALMA image of an enormous sunspot taken on 18 December 2015 with the Band 3 receiver at a wavelength of 3 millimeters. Sunspots are transient features that occur in regions where the Sun’s magnetic field is extremely concentrated and powerful. They are lower in temperature than their surrounding regions, which is why they appear relatively dark in visible light. The ALMA images are essentially maps of temperature differences in a layer of the Sun’s atmosphere known as the chromosphere, which lies just above the visible surface of the Sun (the photosphere). The chromosphere is considerably hotter than the photosphere. Understanding the heating and dynamics of the chromosphere are key areas of research that will be addressed by ALMA. Observations at shorter wavelengths probe deeper into the solar chromosphere than longer wavelengths. Hence, Band 6 observations map a layer of the chromosphere that is closer to the visible surface of the Sun than Band 3 observations. Credit: ALMA (ESO/NAOJ/NRAO)

    These new images demonstrate ALMA’s ability to study solar activity at longer wavelengths than observed with typical solar telescopes on Earth, and are an important expansion of the range of observations that can be used to probe the physics of our nearest star.

    5
    This full map of the Sun at a wavelength of 1.25 mm was taken with a single ALMA antenna using a so-called “fast-scanning” technique. The accuracy and speed of observing with a single ALMA antenna makes it possible to produce a low-resolution map of the entire solar disk in just a few minutes. Such images can be used in their own right for scientific purposes, showing the distribution of temperatures in the chromosphere, the region of the solar atmosphere that lies just above the visible surface of the Sun. Credit: ALMA (ESO/NAOJ/NRAO)

    “We’re accustomed to seeing how our Sun appears in visible light, but that can only tell us so much about the dynamic surface and energetic atmosphere of our nearest star,” said Tim Bastian, an astronomer with the National Radio Astronomy Observatory in Charlottesville, Virginia in the USA. “To fully understand the Sun, we need to study it across the entire electromagnetic spectrum, including the millimeter and submillimeter portion that ALMA can observe.”

    Since our Sun is many billions of times brighter than the faint objects ALMA typically observes, the solar commissioning team had to developed special procedures to enable ALMA to safely image the Sun without damaging its sensitive electronics.

    The result of this work is a series of images that demonstrates ALMA’s unique vision and ability to study our Sun on multiple scales.

    The ALMA Solar Development Team includes Shin’ichiro Asayama, East Asia ALMA Support Center, Tokyo, Japan; Miroslav Barta, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Tim Bastian, National Radio Astronomy Observatory, USA; Roman Brajsa, Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia; Bin Chen, New Jersey Institute of Technology, USA; Bart De Pontieu, LMSAL, USA; Gregory Fleishman, New Jersey Institute of Technology, USA; Dale Gary, New Jersey Institute of Technology, USA; Antonio Hales, Joint ALMA Observatory, Chile; Akihiko Hirota, Joint ALMA Observatory, Chile; Hugh Hudson, School of Physics and Astronomy, University of Glasgow, UK; Richard Hills, Cavendish Laboratory, Cambridge, UK; Kazumasa Iwai, National Institute of Information and Communications Technology, Japan; Sujin Kim, Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea; Neil Philips, Joint ALMA Observatory, Chile; Tsuyoshi Sawada, Joint ALMA Observatory, Chile; Masumi Shimojo, NAOJ, Tokyo, Japan; Giorgio Siringo, Joint ALMA Observatory, Chile; Ivica Skokic, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Sven Wedemeyer, Institute of Theoretical Astrophysics, University of Oslo, Norway; Stephen White, AFRL, USA; Pavel Yagoubov, ESO, Garching, Germany; and Yihua Yan, NAO, Chinese Academy of Sciences, Beijing, China.

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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

    NRAO Small

    ESO 50

    NAOJ

     
  • richardmitnick 12:25 pm on January 17, 2017 Permalink | Reply
    Tags: , , , Basic Research, , Orion Nebula Hubble and VLT, So what does a molecular cloud produce anyway?   

    From astrobites: “So what does a molecular cloud produce, anyway?” 

    Astrobites bloc

    Astrobites

    Title: The bimodal initial mass function in the Orion Nebula Cloud
    Authors: H. Drass, M. Haas, R. Chini, A. Bayo, M. Hackstein, V. Hoffmeister, N. Godoy, N. Vogt
    First Author’s Institutions: Ruhr-Universität Bochum & Pontifica Universidad Católica de Chile
    1
    2
    Status: Published in MNRAS [open access]

    Introduction

    Collapsing regions of molecular clouds produce objects with a range of masses, from teeny planets to stars that are a hundred times the mass of the Sun. The ‘initial mass function’ plots the relative number of bodies as a function of mass. What does the initial mass function look like? And how much does it depend on the local environment? The distribution is determined by the poorly-constrained processes of star formation, which involve physics of the evolution of structure, chemistry, and star formation rates of galaxies, as well as the formation and evolution of stellar and exoplanetary systems. If we can determine the initial mass function exactly, we can help make some headway in these disparate fields.

    There are two alternative theories for how the initial mass function may be formed: the parent core masses in collapsing molecular clouds map directly to the initial mass function, or gravitational interactions affect accretion onto protostars and fling members out of multiple-object systems. It is difficult to tell which effect is most important because, well, it is difficult to measure the initial mass function precisely. Low-mass objects are very dim, and some fade away into complete invisibility as they cool. High-mass stars are easy to detect, but they burn faster and quickly blow away their atmospheres or explode as supernovae.

    The paper

    In this paper, Drass et al. strategically chose to survey the Orion Nebular Cloud (Fig. 1), which is only 1,350 light-years (414 parsecs) away and has produced stars that have not yet been churned around in the Milky Way like the siblings of our own Sun. It is very young, perhaps a couple million years old– so low-mass objects are still glowing with the heat of formation and the first generation of high-mass stars is still present.

    1
    Fig. 1: The Orion Nebula Cloud, with the footprints of different surveys. Drass et al.’s footprint is in black. The circled region is the nebula M43, which Drass et al. removed from their analysis because it may have an initial mass function distinct from the cloud as a whole. (Adapted from Drass et al., Fig. 1; HST images were taken with ACS B, V, H-alpha, I, and Z filters.)

    Orion Nebula M. Robberto NASA ESA Space Telescope Science Institute Hubble
    Orion Nebula M. Robberto NASA ESA Space Telescope Science Institute Hubble

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Orion Nebula VLT
    Orion Nebula VLT

    The authors used the Very Large Telescope in the Atacama Desert in Chile with 1.25, 1.65, and 2.15 micron filters, in which small-mass objects are relatively bright.
    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level
    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    This filter combination also allows each star to be placed on a color-magnitude diagram, which, in combination with models, determines stellar masses or temperatures.

    Drass et al. removed contaminants and overlaid their color-magnitude diagrams with lines called ‘isochrones‘, which indicate model locations of stars of different masses. These were used to convert the colors of the detected stars to actual masses. Voilà– the end result is an initial mass function.

    Conclusion

    Surprisingly, the mass function corresponding to an age of 2-5 million years has two distinct peaks (Fig. 2)! If the Orion Nebula is indeed that old (some think it might actually be younger) and if the isochrones are accurate (isochrones are debatable at the lowest masses), then the Orion Nebular Cloud seems to be preferentially producing objects at around 0.25 and 0.025 solar masses. These correspond to low-mass stars and brown dwarfs. There are also, the authors note, some free-floating planets below the brown dwarf range.

    Drass et al. suggest that this mass function is evidence against a pure one-to-one mapping of the core mass and initial mass functions. Dynamical interactions may indeed have played a role by whipping low-mass objects out of interacting systems and littering the Orion Nebula with orphaned, low-mass objects. It is not possible to definitively prove this with current models, but the authors suggest the answer “has to be searched for along that direction.”

    2
    Fig. 2: Here is the final initial (eh? ) mass function of the Orion Nebula (black line). Different data points were generated using different filter combinations and give a sense of the uncertainty. Green corresponds to the mass function of another region in Orion with very high extinction, where background contaminants are masked by the intervening gas. Red shows the component of the green that is just due to brown dwarfs, and dashed lines show model initial mass functions from the literature. The similarity between the green and the black suggest that contaminants have been adequately accounted for, and that the bimodal nature of the initial mass function is real. (Drass et al., Fig. 12.)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    What do we do?

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

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

     
  • richardmitnick 3:45 pm on January 16, 2017 Permalink | Reply
    Tags: Basic Research, , , ,   

    From SURF: “Neutrinos: Spies of the sun” 

    SURF logo
    Sanford Underground levels

    Sanford Underground Research facility

    November 21, 2016 [Just caught up with this.]
    Constance Walter

    1
    Hydrogen plasma glows at the ion source of the LUNA accelerator. The plasma is needed to extract and accelerate protons. Credit: LUNA experiment

    As a young man, Frank Strieder was fascinated with astrophysics, reading every book he could find and taking high-level courses in math and physics while in high school in Germany. One day in particular stands out.

    “My teacher said, ‘Ah, but neutrinos have never been measured from the sun.’ I said, ‘No, no, no. There’s an experiment by Ray Davis somewhere in the United States at an underground gold mine.’ And the teacher said, ‘No, that is not the case,’” said Strieder, a professor of physics at the South Dakota School of Mines and Technology (SD Mines).

    “Now, almost 30 years later, I’m at that same place doing my own experiment in the same environment,” said Strieder, who is also the principal investigator for CASPAR (Compact Accelerator System for Performing Astrophysical Research) at Sanford Lab.

    For nearly three decades, Davis counted solar neutrinos on the 4850 Level of the former Homestake Mine. But there was a problem. Davis consistently counted only one-third the number of neutrinos predicted by theorists, creating what came to be called the “solar neutrino problem.”

    Initially, the scientific community thought the experiment must be wrong, but Davis insisted he was right. He was vindicated when two underground experiments in Canada and Japan showed that neutrinos oscillate, or change among three types, as they travel through space at nearly the speed of light. In 2002, Davis earned a share of the Nobel Prize in Physics.

    But even before the Nobel, Davis’s work inspired experiments around the world, including the Laboratory for Underground Nuclear Astrophysics (LUNA) at Gran Sasso National Laboratory in Italy.

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO
    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO

    The first underground accelerator for astrophysics, LUNA has been looking at stellar nuclear burning in the sun for 25 years.

    “Ray Davis used neutrinos as spies of the sun, to try to prove what was happening in the sun,” said Matthias Junker, a scientist with the LUNA collaboration. “As we have fixed our idea of what is a neutrino, we can use it to probe what is going on inside the sun.”

    Strieder worked with Junker on the LUNA experiment for 22 years before moving to CASPAR two years ago.

    CASPAR's accelerator is expected to be operational by 2015
    CASPAR’s accelerator is expected to be operational by 2015

    Although both experiments are studying stellar burning and evolutionary phases in stars, their work is different. CASPAR is interested in understanding the production of elements heavier than iron, while LUNA concentrates on the production of elements up to magnesium, aluminum and others in that area.

    “This nuclear burning produces all the isotopes that make up life,” Junker said. “Where does carbon come from? Oxygen? Nitrogen? Lead? Gold? It’s all produced within stars. If you have a better understanding of the stars, you can use them to probe the universe.”

    LUNA and CASPAR are the only experiments doing this type of research, Junker said. “Of course, there is competition but there is also sharing knowledge and experience.”

    And it all started with neutrinos and the pioneering work done by Ray Davis.

    On a recent visit to Sanford Lab, Junker said, “For me, this moment is extremely thrilling. This is the root of neutrino research.”

    See the full article here .

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    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.
    LUX/Dark matter experiment at SURFLUX/Dark matter experiment at SURF

    In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

    Fermilab LBNE
    LBNE

     
  • richardmitnick 2:34 pm on January 16, 2017 Permalink | Reply
    Tags: , , Basic Research, brightest galaxies shine a ghostly green in surprising new find, , Earliest,   

    From Ethan Siegel: “Earliest, brightest galaxies shine a ghostly green in surprising new find” 

    From Ethan Siegel
    1.16.17

    Only a few galaxies exhibit this green glow in the nearby Universe. At early times, it’s practically all of the brightest ones.

    1
    Some rare galaxies exhibit a green glow thanks to the presence of doubly ionized oxygen. This requires UV light from stellar temperatures of 50,000 K and above. Image credit: NASA, ESA, and W. Keel (University of Alabama, Tuscaloosa), of NGC 5972.

    “The discovery that young galaxies are so unexpectedly bright–if you look for this distinctive green light–will dramatically change and improve the way that we study Galaxy formation throughout the history of the Universe.”
    -Matthew Malkan

    Here in the nearby Universe, 13.8 billion years since the Big Bang, galaxies come in great varieties.

    2
    A great variety of galaxies in color, morphology, age and inherent stellar populations can be seen in this deep-field image. Image credit: NASA, ESA, R. Windhorst, S. Cohen, M. Mechtley, and M. Rutkowski (Arizona State University, Tempe), R. O’Connell (University of Virginia), P. McCarthy (Carnegie Observatories), N. Hathi (University of California, Riverside), R. Ryan (University of California, Davis), H. Yan (Ohio State University), and A. Koekemoer (Space Telescope Science Institute).

    Spirals, ellipticals, rings and irregulars, they glow blue, white or red, depending on their stellar populations.

    3
    Galaxies undergoing massive bursts of star formation expel large quantities of matter at great speeds. They also glow red covering the whole galaxy, thanks to hydrogen emissions. Image credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA), of the Cigar Galaxy, Messier 82.

    The most violent star-forming galaxies and nebulae are so hot they turn red, as ultraviolet radiation ionizes neutral hydrogen.

    4
    The great Orion Nebula is a fantastic example of an emission nebula, as evidenced by its red hues and its characteristic emission at 656.3 nanometers. Image credit: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team.

    5
    This image from ESO’s Very Large Telescope shows the glowing green planetary nebula IC 1295 surrounding a dim and dying star located about 3300 light-years away. Image credit: ESO / FORS instrument.

    But there’s another, green line that happens only when oxygen gets doubly ionized at the hottest temperatures of all: 50,000 K and above.

    6
    Modern ‘green pea’ galaxies have their doubly-ionized oxygen emission offset from the main galaxy; in the Subaru Deep Field, the galaxies themselves exhibit the strong emission. Image credit: NASA, ESA, and Z. Levay (STScI), with science by NASA, ESA, and W. Keel (University of Alabama, Tuscaloosa).

    Only planetary nebulae, with super-hot young white dwarfs, and the ultra-rare “green pea” galaxies exhibit these features.

    7
    The Subaru Deep Field, containing thousands of distant galaxies exhibiting these oxygen lines. Image credit: Subaru telescope, National Astronomical Observatory of Japan (NAOJ); Image processing: R. Jay GaBany.

    But by looking at the most active star-forming galaxies in the Subaru Deep Field (above), Matthew Malkan and Daniel Cohen found, that all galaxies from 11 billion years ago or more emit this green signature.

    8
    The strong green emission line (highest point) as shown in a sample of over 1,000 galaxies, spectrally stacked from the Subaru Deep Field. The other point “above” the curves is from hydrogen; the strong green oxygen line indicates incredibly intense radiation. Image credit: Malkan and Cohen (2017).

    The unexpected brightness and hotness of these galaxies hints that the stars in the ultra-distant Universe are somehow hotter than the hottest stars today.

    9
    The merging star clusters at the heart of the Tarantula Nebula, which contains the hottest stars in the local group, are still below 50,000 K. Perhaps lower metallicities, higher masses, or even a top-heavy initial mass function among stars in the early Universe are responsible for the increased, high temperatures. Image credit: NASA, ESA, and E. Sabbi (ESA/STScI); Acknowledgment: R. O’Connell (University of Virginia) and the Wide Field Camera 3 Science Oversight Committee.

    10
    The reionization and star-formation history of our Universe. The study hints that green, oxygen-rich galaxies may have been responsible for reionization. Image credit: NASA / S.G. Djorgovski & Digital Media Center / Caltech.

    JWST, launching 2018, will find out for sure.

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 1:56 pm on January 16, 2017 Permalink | Reply
    Tags: , Basic Research, FO Aquarii, , Sarah L. Krizmanich Telescope   

    From Notre Dame: “Notre Dame astrophysicists discover dimming of binary star’ 

    Notre Dame bloc

    Notre Dame University

    January 16, 2017
    Brian Wallheimer

    A team of University of Notre Dame astrophysicists led by Peter Garnavich, professor of physics, has observed the unexplained fading of an interacting binary star, one of the first discoveries using the University’s Sarah L. Krizmanich Telescope.

    Notre Dame Rooftop Sarah L Krizmanich  Telescope
    Notre Dame Rooftop Sarah L Krizmanich  Telescope Interior
    Notre Dame Rooftop Sarah L Krizmanich Telescope

    The binary star, FO Aquarii, located in the Milky Way galaxy and Aquarius constellation about 500 light-years from Earth, consists of a white dwarf and a companion star donating gas to the compact dwarf, a type of binary system known as an intermediate polar. The system is bright enough to be observed with small telescopes. Garnavich and his team started studying FO Aquarii, known as “king of the intermediate polars,” a few years ago when NASA’s Kepler Telescope was pointed toward it for three months. The star rotates every 20 minutes, and Garnavich wanted to investigate whether the period was changing.

    “I asked Erin Aadland, an REU student, to precisely measure the spin rate of a white dwarf. Does it speed up or slow down?” he said. “We can do that by looking at the interval between flashes from the star just like we use the ticks in a clock to tell time. The star turned out to have other plans for the summer.”

    Intermediate polars are interesting binary systems because the low-density star drops gas toward the compact dwarf, which catches the matter using its strong magnetic field and funnels it to the surface, a process called accretion. The gas emits X-rays and optical light as it falls, and we see regular light variations as the stars orbit and spin. Graduate student Mark Kennedy studied the light variations in detail during the three months the Kepler Space Telescope was pointing at FO Aquarii in 2014. Kennedy is a Naughton Fellow from University College, Cork, in Ireland who spent a year and a half working at Notre Dame on interacting binary stars. “Kepler observed FO Aquarii every minute for three months, and Mark’s analysis of the data made us think we knew all we could know about this star,” Garnavich said.

    Once Kepler was pointed in a new direction, Garnavich and his group used the Krizmanich Telescope to continue the study.

    “Just after the star came around the sun last year, we started looking at it through the Krizmanich Telescope, and we were shocked to see it was seven times fainter than it had ever been before,” said Colin Littlefield, a member of the Garnavich lab. “The dimming is a sign that the donating star stopped sending matter to the compact dwarf, and it’s unclear why. Although the star is becoming brighter again, the recovery to normal brightness has been slow, taking over six months to get back to where it was when Kepler observed.”

    “Normally, the light that we’d see would come from the accretion energy, and it got a lot weaker when the gas flow stopped. We are now following the recovery over months,” Garnavich said.

    One theory is that a star spot, a cool region on the companion, rotated into just the right position to disrupt the flow of hydrogen from the donating star. But that doesn’t explain why the star hasn’t then recovered as quickly as it dimmed.

    Garnavich and his team also found that the light variations of FO Aquarii became very complex during its low state. The low gas transfer rate had meant the dominant, 20-minute signal had faded and allowed other periods to show up. Instead of a steady 20 minutes between flashes, sometimes there was an 11-minute signal and at other times a 21-minute pulse.

    “We had never seen anything like this before,” Garnavich said. “For two hours, it would flash quickly and then the next two hours it would pulse more slowly.”

    The Sarah L. Krizmanich Telescope, installed on the roof of the Jordan Hall of Science in 2013, features a 0.8-meter (32-inch diameter) mirror. It provides undergraduate and graduate students cutting-edge technology for research and is used to test new instrumentation developed in the Department of Physics at Notre Dame.

    The Notre Dame team that studied FO Aquarii included Littlefield, Aadland and Kennedy. The team’s findings have been published in the Astrophysical Journal. Institutions that contributed to the work include The Ohio State University, University Cote d’Azur (France), University de Liege (Belgium) and the American Association of Variable Star Observers (AAVSO)

    See the full article here .

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    Notre Dame Campus

    The University of Notre Dame du Lac (or simply Notre Dame /ˌnoʊtərˈdeɪm/ NOH-tər-DAYM) is a Catholic research university located near South Bend, Indiana, in the United States. In French, Notre Dame du Lac means “Our Lady of the Lake” and refers to the university’s patron saint, the Virgin Mary.

    The school was founded by Father Edward Sorin, CSC, who was also its first president. Today, many Holy Cross priests continue to work for the university, including as its president. It was established as an all-male institution on November 26, 1842, on land donated by the Bishop of Vincennes. The university first enrolled women undergraduates in 1972. As of 2013 about 48 percent of the student body was female.[6] Notre Dame’s Catholic character is reflected in its explicit commitment to the Catholic faith, numerous ministries funded by the school, and the architecture around campus. The university is consistently ranked one of the top universities in the United States and as a major global university.

    The university today is organized into five colleges and one professional school, and its graduate program has 15 master’s and 26 doctoral degree programs.[7][8] Over 80% of the university’s 8,000 undergraduates live on campus in one of 29 single-sex residence halls, each of which fields teams for more than a dozen intramural sports, and the university counts approximately 120,000 alumni.[9]

    The university is globally recognized for its Notre Dame School of Architecture, a faculty that teaches (pre-modernist) traditional and classical architecture and urban planning (e.g. following the principles of New Urbanism and New Classical Architecture).[10] It also awards the renowned annual Driehaus Architecture Prize.

     
  • richardmitnick 12:06 pm on January 16, 2017 Permalink | Reply
    Tags: ASKAP finally hits the big-data highway, , Basic Research, , , , , , WALLABY - Widefield ASKAP L-band Legacy All-sky Blind surveY   

    From The Conversation for SKA: “The Australian Square Kilometre Array Pathfinder finally hits the big-data highway” 

    Conversation
    The Conversation

    SKA Square Kilometer Array

    SKA

    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia
    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia

    January 15, 2017
    Douglas Bock
    Director of Astronomy and Space Science, CSIRO

    Antony Schinckel
    ASKAP Director, CSIRO

    You know how long it takes to pack the car to go on holidays. But there’s a moment when you’re all in, everyone has their seatbelt on, you pull out of the drive and you’re off.

    Our ASKAP (Australian Square Kilometre Array Pathfinder) telescope has just pulled out of the drive, so to speak, at its base in Western Australia at the Murchison Radio-astronomy Observatory (MRO), about 315km northeast of Geraldton.

    ASKAP is made of 36 identical 12-metre wide dish antennas that all work together, 12 of which are currently in operation. Thirty ASKAP antennas have now been fitted with specialised phased array feeds, the rest will be installed later in 2017.

    Until now, we’d been taking data mainly to test how ASKAP performs. Having shown the telescope’s technical excellence it’s now off on its big trip, starting to make observations for the big science projects it’ll be doing for the next five years.

    And it’s taking lots of data. Its antennas are now churning out 5.2 terabytes of data per second (about 15 per cent of the internet’s current data rate).

    Once out of the telescope, the data is going through a new, almost automatic data-processing system we’ve developed.

    It’s like a bread-making machine: put in the data, make some choices, press the button and leave it overnight. In the morning you have a nice batch of freshly made images from the telescope.

    Go the WALLABIES

    The first project we’ve been taking data for is one of ASKAP’s largest surveys, WALLABY (Widefield ASKAP L-band Legacy All-sky Blind surveY).

    On board the survey are a happy band of 100-plus scientists – affectionately known as the WALLABIES – from many countries, led by one of our astronomers, Bärbel Koribalski, and Lister Staveley-Smith of the International Centre for Radio Astronomy Research (ICRAR), University of Western Australia.

    They’re aiming to detect and measure neutral hydrogen gas in galaxies over three-quarters of the sky. To see the farthest of these galaxies they’ll be looking three billion years back into the universe’s past, with a redshift of 0.26.

    2
    Neutral hydrogen gas in one of the galaxies, IC 5201 in the southern constellation of Grus (The Crane), imaged in early observations for the WALLABY project. Matthew Whiting, Karen Lee-Waddell and Bärbel Koribalski (all CSIRO); WALLABY team, Author provided

    Neutral hydrogen – just lonely individual hydrogen atoms floating around – is the basic form of matter in the universe. Galaxies are made up of stars but also dark matter, dust and gas – mostly hydrogen. Some of the hydrogen turns into stars.

    Although the universe has been busy making stars for most of its 13.7-billion-year life, there’s still a fair bit of neutral hydrogen around. In the nearby (low-redshift) universe, most of it hangs out in galaxies. So mapping the neutral hydrogen is a useful way to map the galaxies, which isn’t always easy to do with just starlight.

    But as well as mapping where the galaxies are, we want to know how they live their lives, get on with their neighbours, grow and change over time.

    When galaxies live together in big groups and clusters they steal gas from each other, a processes called accretion and stripping. Seeing how the hydrogen gas is disturbed or missing tells us what the galaxies have been up to.

    We can also use the hydrogen signal to work out a lot of a galaxy’s individual characteristics, such as its distance, how much gas it contains, its total mass, and how much dark matter it contains.

    This information is often used in combination with characteristics we learn from studying the light of the galaxy’s stars.

    Oh what big eyes you have ASKAP

    ASKAP sees large pieces of sky with a field of view of 30 square degrees. The WALLABY team will observe 1,200 of these fields. Each field contains about 500 galaxies detectable in neutral hydrogen, giving a total of 600,000 galaxies.

    3
    One of the first fields targeted by WALLABY, the NGC 7232 galaxy group. Ian Heywood (CSIRO); WALLABY team, Author provided

    This image (above) of the NGC 7232 galaxy group was made with just two nights’ worth of data.

    ASKAP has now made 150 hours of observations of this field, which has been found to contain 2,300 radio sources (the white dots), almost all of them galaxies.

    It has also observed a second field, one containing the Fornax cluster of galaxies, and started on two more fields over the Christmas and New Year period.

    Even more will be dug up by targeted searches. Simply detecting all the WALLABY galaxies will take more than two years, and interpreting the data even longer. ASKAP’s data will live in a huge archive that astronomers will sift through over many years with the help of supercomputers at the Pawsey Centre in Perth, Western Australia.

    ASKAP has nine other big survey projects planned, so this is just the beginning of the journey. It’s really a very exciting time for ASKAP and the more than 350 international scientists who’ll be working with it.

    Who knows where this Big Trip will take them, and what they’ll find along the way?

    See the full article here .

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    The Conversation US launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 11:32 am on January 16, 2017 Permalink | Reply
    Tags: A slice of Sagittarius, , Basic Research, NASA/ESA Hubble ACS   

    From Hubble: “A slice of Sagittarius” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    1
    Credit: NASA/ESA Hubble

    16 January 2017
    No writer credit found

    This stunning image, captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), shows part of the sky in the constellation of Sagittarius (The Archer).

    NASA/ESA Hubble ACS

    The region is rendered in exquisite detail — deep red and bright blue stars are scattered across the frame, set against a background of thousands of more distant stars and galaxies. Two features are particularly striking: the colours of the stars, and the dramatic crosses that burst from the centres of the brightest bodies.

    While some of the colours in this frame have been enhanced and tweaked during the process of creating the image from the observational data, different stars do indeed glow in different colours. Stars differ in colour according to their surface temperature: very hot stars are blue or white, while cooler stars are redder. They may be cooler because they are smaller, or because they are very old and have entered the red giant phase, when an old star expands and cools dramatically as its core collapses.
    The crosses are nothing to do with the stars themselves, and, because Hubble orbits above Earth’s atmosphere, nor are they due to any kind of atmospheric disturbance. They are actually known as diffraction spikes, and are caused by the structure of the telescope itself. Like all big modern telescopes, Hubble uses mirrors to capture light and form images. Its secondary mirror is supported by struts, called telescope spiders, arranged in a cross formation, and they diffract the incoming light. Diffraction is the slight bending of light as it passes near the edge of an object. Every cross in this image is due to a single set of struts within Hubble itself! Whilst the spikes are technically an inaccuracy, many astrophotographers choose to emphasise and celebrate them as a beautiful feature of their images.

    See the full article here .

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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    AURA Icon

    NASA image

     
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