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  • richardmitnick 6:38 pm on April 29, 2016 Permalink | Reply
    Tags: , , , Oxygen Abundance in Giant Stars   

    From CfA: “Oxygen in Stars” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    April 29, 2016

    1
    An optical image of the brightest globular cluster, Omega Centauri, a group of over ten million stars older than the Sun. Astronomers have developed a new computational method to determine the abundance of oxygen in these and similar stars, and in particular in giant stars. The code finds values that are more self-consistent than previous estimates. Joaquin Polleri & Ezequiel Etcheverry, Observatorio Panameño en San Pedro de Atacama

    Oxygen is the third most abundant element in the universe, after hydrogen and helium. It is an important constituent of the clouds of gas and dust in space, especially when combined in molecules with other atoms like carbon, and it is from this interstellar material that new stars and planets develop. Oxygen is, of course, also essential for life as we know it, and all known life forms require liquid water and its oxygen content. Oxygen in molecular form, especially as water, was supposed to be relatively abundant, but over the past decade considerable attention has been paid to observations suggesting that at least in molecular form oxygen is scarcer than expected, a deficit that has not yet been entirely resolved.

    Atomic oxygen by contrast, seen most prominently in the light of stars, was thought to be in good agreement with expectations. The neutral oxygen atom produces strong lines that are frequently used to calculate its abundance. Models fit the line strengths by taking into account the radiation field, the star’s hot gas motions, and the internal structure of the star (for example, the way the temperature and pressure change with radius). It turns out, however, that varying assumptions in these calculations can result in oxygen abundance predictions that differ significantly, and in the case of giant stars, which are larger and cooler and often have hot outer chromospheres, those abundance results can disagree with one another by as much as a factor of 15. This discrepancy has often been discounted by scientists arguing that some of the proposed stellar models are themselves unrealistic.

    CfA astronomers Andrea Dupree, Eugene Avrett, and Bob Kurucz have tacked this fundamental problem with Avrett’s PANDORA code for stellar atmospheres. In particular, they include the effects of a hot outer atmosphere in giant stars, something that was typically ignored. Moreover, they do not tie the excitation of oxygen atoms (and the corresponding line strengths) to the local temperature. That constraint, imposed by most previous methods in order to simplify the calculations, does not take more complex situations (like the hot atmosphere) adequately into account. The astronomers find that their new computations can resolve several outstanding issues. The lines themselves are actually as much as three times stronger than previously thought, reducing the implied oxygen abundances, and thereby also affecting details of the stellar interior models, especially for giants seen in globular clusters of stars. Similar improvements are seen in the results for stars known to be lacking other heavier elements, and even some normal, Sun-like stars. The possible implications extend to estimating more accurately the amount of oxygen present in a solar nebula when exoplanets form.

    Science paper:
    Chromospheric Models and the Oxygen Abundance in Giant Stars, A. K. Dupree, E. H. Avrett, and R. L. Kurucz, ApJ 821, L7, 2016

    See the full article here .

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    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 6:27 pm on April 29, 2016 Permalink | Reply
    Tags: , , Planet habitability   

    From Eos: “Becoming Habitable in the Habitable Zone” 

    Eos news bloc

    Eos

    4.29.16
    Sarah Stanley

    1
    An artist’s rendition of Kepler-186f, an Earth-size planet in the habitable zone of a distant solar system. Little is known about its composition, but if it turns out to be rocky like Earth, it may be subject to climate-mantle-core interactions that determine whether it can actually sustain life. Credit: NASA Ames/SETI Institute/JPL-Caltech

    Day to day, plate tectonics may seem to have little to do with Earth’s habitability. However, over time, interactions between our planet’s climate, mantle, and core have created a suitable home for complex life.

    Techtonic plates, USGS, 1996
    The tectonic plates of the world were mapped in 1996, USGS.

    In a new review paper*, Foley and Driscoll suggest that similar processes could set other rocky planets on very different trajectories, ultimately determining whether they could support life as we know it.

    Cooler climates promote plate tectonics by keeping plate boundaries from fusing and by weakening the crust and outer mantle. In turn, plate tectonics help keep the climate temperate through carbon cycling. On Earth, cold slabs of rock subduct and sink deep into the mantle, drawing heat from the core. Long-term core cooling helps maintain Earth’s magnetic field, which keeps the solar wind from stripping away the atmosphere.

    The authors hypothesize that the climate-mantle-core connection determines whether a young, rocky planet will develop plate tectonics, a temperate climate, and a magnetic field—all of which are thought to be necessary for life. Initial atmospheric composition, timing of the onset of plate tectonics, and other factors can affect how climate-mantle-core dynamics unfold. This means that two similar planets might follow wildly different paths, even if they both reside in a solar system’s habitable zone (where liquid water can exist on the surface).

    The authors also suggest that interactions between the climate, mantle, and core might explain why Earth and Venus are so different, despite their similar sizes and composition: Venus’s hot climate prevents plate tectonics, stifling a sustained magnetic field.

    Scientists don’t yet know enough Venusian history to confirm the authors’ hypothesis. Much more research is also needed to clarify connections between climate, mantle, and core for rocky planets in general, but a better understanding of these dynamics could help predict the likelihood of finding an Earth-like exoplanet. (Geochemistry, Geophysics, Geosystems, doi:10.1002/2015GC006210, 2016).

    *Science paper:
    Whole planet coupling between climate, mantle, and core: Implications for rocky planet evolution

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 3:40 pm on April 29, 2016 Permalink | Reply
    Tags: , , Speed of Gravity,   

    From Ethan Siegel: “Why Does Gravity Move At The Speed Of Light?” 

    Starts with a Bang

    4.28.16
    Ethan Siegel

    1
    Image credit: European Gravitational Observatory, Lionel BRET/EUROLIOS.

    If you looked out at the Sun across the 93 million miles of space that separate our world from our nearest star, the light you’re seeing isn’t from the Sun as it is right now, but rather as it was some 8 minutes and 20 seconds ago. This is because as fast as light is — moving at the speed of light — it isn’t instantaneous: at 299,792.458 kilometers per second (186,282 miles per second), it requires that length of time to travel from the Sun’s photosphere to our planet. But gravitation doesn’t necessarily need to be the same way; it’s possible, as Newton’s theory predicted, that the gravitational force would be an instantaneous phenomenon, felt by all objects with mass in the Universe across the vast cosmic distances all at once.

    2
    Image credit: NASA/JPL-Caltech, for the Cassini mission.

    But is that right? If the Sun were to simply wink out of existence, would the Earth immediately fly off in a straight line, or would it continue orbiting the Sun’s location for another 8 minutes and 20 seconds? If you ask General Relativity, the answer is much closer to the latter, because it isn’t mass that determines gravitation, but rather the curvature of space, which is determined by the sum of all the matter and energy in it. If you were to take the Sun away, space would go from being curved to being flat, but that transformation isn’t instantaneous. Because spacetime is a fabric, that transition would have to occur in some sort of “snapping” motion, which would send very large ripples — i.e., gravitational waves — through the Universe, propagating outward like ripples in a pond.

    3
    Image credit: Sergiu Bacioiu from Romania, under c.c.-2.0 generic.

    The speed of those ripples is determined the same way the speed of anything is determined in relativity: by their energy and their mass. Since gravitational waves are massless yet have a finite energy, they must move at the speed of light! Which means, if you think about it, that the Earth isn’t directly attracted to the Sun’s location in space, but rather to where the Sun was located a little over 8 minutes ago.

    4
    Image credit: David Champion, Max Planck Institute for Radio Astronomy.

    If that were the only difference between Einstein’s theory of gravity and Newton’s, we would have been able to instantly conclude that Einstein’s theory was wrong. The orbits of the planets were so well studied and so precisely recorded for so long (since the late 1500s!) that if gravity simply attracted the planets to the Sun’s prior location at the speed of light, the planets’ predicted locations would mismatch severely with where they actually were. It’s a stroke of brilliance to realize that Newton’s laws require an instantaneous speed of gravity to such precision that if that were the only constraint, the speed of gravity must have been more than 20 billion times faster than the speed of light!

    But in General Relativity, there’s another piece to the puzzle that matters a great deal: the orbiting planet’s velocity as it moves around the Sun. The Earth, for example, since it’s also moving, kind of “rides” over the ripples traveling through space, coming down in a different spot from where it was lifted up. It looks like we have two effects going on: each object’s velocity affects how it experiences gravity, and so do the changes that occur in gravitational fields.

    5
    Image credit: LIGO/T. Pyle, of a model of distorted space in the Solar System.

    What’s amazing is that the changes in the gravitational field felt by a finite speed of gravity and the effects of velocity-dependent interactions cancel almost exactly! The inexactness of the cancellation is what allows us to determine, observationally, if Newton’s “infinite speed of gravity” model or Einstein’s “speed of gravity = speed of light” model matches with our Universe. In theory, we know that the speed of gravity should be the same as the speed of light. But the Sun’s force of gravity out here, by us, is far too weak to measure this effect. In fact, it gets really hard to measure, because if something moves at a constant velocity in a constant gravitational field, there’s no observable affect at all. What we’d want, ideally, is a system that has a massive object moving with a changing velocity through a changing gravitational field. In other words, we want a system that consists of a close pair of orbiting, observable stellar remnants, at least one of which is a neutron star.


    Access mp4 video here .

    As one or both of these neutron stars orbit, they pulse, and the pulses are visible to us here on Earth each time the pole of a neutron star passes through our line-of-sight. The predictions from Einstein’s theory of gravity are incredibly sensitive to the speed of light, so much so that even from the very first binary pulsar system discovered in the 1980s, PSR 1913+16 (or the Hulse-Taylor binary), we have constrained the speed of gravity to be equal to the speed of light with a measurement error of only 0.2%!

    6
    Image credit: NASA (L), Max Planck Institute for Radio Astronomy / Michael Kramer, via http://www.mpg.de/7644757/W002_Physics-Astronomy_048-055.pdf.

    That’s an indirect measurement, of course. We were able to do another type of indirect measurement in 2002, when a chance coincidence lined up the Earth, Jupiter, and a very strong radio quasar (QSO J0842+1835) all along the same line-of-sight! As Jupiter moved between Earth and the quasar, the gravitational bending of Jupiter allowed us to measure the speed of gravity, ruling out an infinite speed and determining that the speed of gravity was between 2.55 × 10^8 and 3.81 × 10^8 meters-per-second, completely consistent with Einstein’s predictions.

    7
    The quasar QSO J0842+1835, whose path was gravitationally altered by Jupiter in 2002, allowing an indirect confirmation that the speed of gravity equals the speed of light. Image credit: Fomalont et al. (2000), ApJS 131, 95-183, via http://www.jive.nl/svlbi/vlbapls/J0842+1835.htm.

    Ideally, we’d be able to measure the speed of these ripples directly, from the direct detection of a gravitational wave. LIGO just saw the first one, after all! Unfortunately, due to our inability to correctly triangulate the location from which these waves originated, we don’t know from which direction the waves were coming. By calculating the distance between the two independent detectors (in Washington and Louisiana) and measuring the difference in the signal arrival time, we can determine that the speed of gravity is consistent with the speed of light, but can only place an absolute constraint that it’s equal to the speed of light within 70%.

    8
    The gravitational wave arrival at the two detectors in WA and LA, with an uncertain origin to their direction. Image credit: Diego Blas, Mikhail M. Ivanov, Ignacy Sawicki, Sergey Sibiryakov, via https://arxiv.org/abs/1602.04188.

    Still, it’s the indirect measurements from very rare pulsar systems that give us the tightest constraints. The best results, at the present time, tell us that the speed of gravity is between 2.993 × 10^8 and 3.003 × 10^8 meters per second, which is an amazing confirmation of General Relativity and a terrible difficulty for alternative theories of gravity that don’t reduce to General Relativity! (Sorry, Newton!) And now you know not only what the speed of gravity is, but where to look to figure it out!

    See the full article here .

    Please help promote STEM in your local schools.

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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 3:01 pm on April 29, 2016 Permalink | Reply
    Tags: , , , Superluminous Supernova   

    From DES- “From the DArchive: A Newly Discovered Superluminous Supernova” 

    Dark Energy Icon

    The Dark Energy Survey

    April 29, 2016
    Mathew Smith
    Edited by R.C. Wolf & R. Cawthon

    Science paper:
    DES14X3taz: A Type I Superluminous Supernova Showing a Luminous, Rapidly Cooling Initial Pre-Peak Bump

    In this paper we present DES14X3taz, a newly discovered superluminous supernova (SLSN). This particular SLSN is very unusual – if you look at the evolution of its brightness over time, or its light curve, there are two peaks (most only have one)! In our analysis, we attempt to explain what physical process might cause such an occurrence and determine if this is truly a unique event or common to all SLSNe.

    Although the initial DECam data was fairly indicative that this was a particularly interesting object, we had to use additional information to confirm our discovery. By combining optical light-curve data from DES and its sister survey, the Survey Using Decam for Superluminous Supernovae (SUDSS), we were able to plot the evolution of brightness over time (light-curve) of DES14X3taz and find its brightest point. We then used spectra obtained on the Gran Telescopino Canarias (GTC) in La Palma, Spain to estimate the distance to this event, and thus its peak brightness, and unambiguously confirmed that it is a SLSNe.

    Gran Telescopino Canarias exterior
    Gran Telescopino de Canaries interior
    Gran Telescopino de Canaries

    What really distinguishes DES14X3taz from previously discovered SLSNe is the presence of an early “bump” in the light curve prior to the main light-curve. The figure below shows these features for DES14X3taz.

    1

    In addition to detecting this bump, we were lucky to have observed this SLSN before explosion and to have observed it at many points during its lifetime; most other observed SLSNe have been discovered post-explosion or do not have such a large a sample of measurements.

    Our observations with DECam allowed us to obtain colour information, from observations in several filters, of the bump. This enabled us to probe the physical processes driving these super-luminous events by comparing our data to pre-existing theoretical models. In the figure below, the colored-circle points are real data, and the dashed lines represent theoretical observations for different physical processes that we think might be motivating this behavior.

    2

    Fitting models to the main curve show that the physical mechanism driving the explosion is consistent with a magnetar, a rapidly rotating neutron star (as seen in the match to the Extended Material Around the Star). In the figure, this is consistent with the solid lines. Fitting black-body curves to the DES data of DES14X3taz, we show that the initial peak cools rapidly, before a period of reheating, which drives the main part of the light-curve. Using chi-squared statistics, we compare photometric data of the initial peak with various models of shock-cooling and find that shock from material at an extended radius is consistent with observations. We also find a sample of previously discovered SLSNe that also exhibit this early bump in their light curves; therefore, we believe our findings suggest a unified physical interpretation for all SLSNe.

    SLSNe are a new class of transient event, with potentially exciting consequences for cosmology. Recent work (Inserra & Smartt 2014) has suggested that these events may even be “standardisable candles”, and thus useful to measure distances to the high redshift Universe. As these events are more luminous than traditional Type Ia supernovae they have the potential to extend SN cosmology to larger distances than currently possible. However, little is well-understood about the explosion mechanism driving these events and we will need to understand more about the origin of SLSNe as we explore utilizing them as cosmological probes.

    See the full article here .

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    DECam, built at FNAL
    DECam, built at FNAL
    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco Telescope at Cerro Tololo which houses the DECAm

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and [has mounted] it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Started in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

     
  • richardmitnick 2:42 pm on April 29, 2016 Permalink | Reply
    Tags: , , ,   

    From Ethan Siegel: “Why Massive Neutrinos Are The Future Of Physics” 

    Starts with a bang
    Starts with a Bang

    Nov 3, 2015
    Ethan Siegel

    1
    Image credit: Tomasz Barszczak, via http://www.ps.uci.edu/~tomba/sk/tscan/compare_mu_e/.

    They won this year’s Nobel Prize in Physics, but their legacy’s just beginning.

    “I know all about neutrinos, and my friend here knows about everything else in astrophysics.” -John Bahcall, neutrino scientist

    If you want to describe the Universe we live in today, from a physical point of view, there are only three things you need to understand:

    What different types of particles are allowed to be present within it,
    What the laws are that govern the interactions between all those different particles, and
    What initial conditions the Universe starts off with.

    If you give a scientist all of those things and an arbitrary amount of calculational power, they can reproduce the entirety of the Universe we experience today, limited only by the quantum uncertainty inherent to our experience.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    SDSS Telescope at Apache Point, NM, USA
    SDSS Telescope at Apache Point, NM, USA

    In the 1960s, what we generally know as the Standard Model of elementary particles and their interactions came about, describing six quarks, three charged leptons, three massless neutrinos, along with the single photon for the electromagnetic force, the three W-and-Z bosons for the weak force, the eight gluons for the strong nuclear force, and the Higgs boson alongside them, to give mass to the fundamental particles in the Universe.

    The Standard Model of elementary particles , with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.
    The Standard Model of elementary particles , with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Along with gravity, which is governed by Einstein’s general relativity, this accounts for the full suite of behavior of every individual particle ever directly detected.

    There are some mysteries that we don’t understand right now about the Universe, such as:

    why there’s more matter than antimatter,
    why there’s CP-violation in the weak interactions but not the strong interactions,
    what the nature of dark matter in the Universe is,
    why the fundamental constants and particle masses have the values they do,
    or where dark energy comes from.

    But for the particles that we have, the Standard Model does it all. Or rather, the Standard Model did it all, until we started looking closely at the almost invisible signals coming from the Sun: the neutrinos.

    Sun. Kelvinsong in Wikipedia
    Sun. Kelvinsong in Wikipedia

    The Sun is powered by nuclear fusion, where hydrogen nuclei are fused together at the tremendous temperatures and energies in the Sun’s core into helium. In the process, they emit large amounts of energy in the form of photons, and also energetic neutrinos. For every four protons that you fuse into a helium nucleus — the net result of fusion in the Sun — you produce two neutrinos. More specifically, you produce two anti-electron neutrinos, a very specific flavor of neutrino.

    Yet when we compute how many neutrinos ought to be produced, and we calculate how many we ought to be able to observe on Earth given our current technology, we only see about a third of the expected number: around 34%.

    Borexino Solar Neutrino detector
    INFN/Borexino Solar Neutrino detector, Gran Sasso, Italy

    Throughout the 1960s, 70s, 80s and 90s, most scientists lambasted either the experimental procedures used to detect these neutrinos, or decried the model of the Sun, claiming that something must be wrong. Yet as both theory and experiment improved, these results held up. It was almost like the neutrinos were disappearing, somehow. There was a radical theory proposed, however: that there was some new physics beyond the Standard Model that was at play, giving a tiny but non-zero mass to all the neutrinos, which would allow them to mix together. When they pass through matter and interact — ever so slightly — with it, this mixing enabled one flavor of neutrino (electron, muon or tau) to oscillate into a different one.

    3
    Image credit: Wikimedia Commons user Strait.

    It was only when we gained the capabilities to detect these other flavors of neutrino, at both Super-Kamiokande and the Sudbury Neutrino Observatory, that we learned that these neutrinos weren’t missing after all, but were transforming from one flavor (the electron-type) into another (the muon or tau type)!

    Super-Kamiokande experiment Japan
    Super-Kamiokande experiment Japan

    SNOLAB, Sudbury, Ontario, Canada.
    SNOLAB, Sudbury, Ontario, Canada

    We now know that all the neutrinos generated are electron (anti)neutrinos, but by time they reach us on Earth, they’re split ⅓, ⅓, ⅓ between the three flavors. Moreover, we’ve measured their masses from these experiments, determining that they’re somewhere between about 1 and a few hundred milli-electron-Volts, or less than one millionth the mass of the next-lightest particle: the electron.

    4
    Image credit: Hitoshi Murayama of http://hitoshi.berkeley.edu/.

    Yes, neutrinos oscillate from one flavor to another, and yes, they have mass. But the real reason it matters is this: for the first time, we have evidence that the particles in the Standard Model — the known, discovered particles in the Universe — have properties that aren’t described by the Standard Model at all!

    There’s more physics out there to be discovered, and this is the first clue of what it might be. So while high energies and the LHC haven’t seen any signs of it, the lowest mass particles show us that there’s more out there than we currently know. And that’s a mystery that’s only expected to deepen the more closely we look.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    “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 1:51 pm on April 29, 2016 Permalink | Reply
    Tags: Asteroid C/2014 S3 (PANSTARRS), , ,   

    From ESO: “Unique Fragment from Earth’s Formation Returns after Billions of Years in Cold Storage” 

    ESO 50 Large

    European Southern Observatory

    29 April 2016
    Karen Meech
    Institute for Astronomy, University of Hawai`i
    Honolulu, HI, USA
    Tel: +1 808 956 6828
    Cell: +1 720 231 7048
    Email: meech@ifa.hawaii.edu

    Olivier Hainaut
    ESO Astronomer
    Garching bei München, Germany
    Tel: +49 89 3200 6752
    Cell: +49 151 2262 0554
    Email: ohainaut@eso.org

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

    Tailless Manx comet from Oort Cloud brings clues about the origin of the Solar System

    1

    Astronomers have found a unique object that appears to be made of inner Solar System material from the time of Earth’s formation, which has been preserved in the Oort Cloud far from the Sun for billions of years. Observations with ESO’s Very Large Telescope, and the Canada France Hawai`i Telescope, show that C/2014 S3 (PANSTARRS) is the first object to be discovered on a long-period cometary orbit that has the characteristics of a pristine inner Solar System asteroid.

    CFHT Telescope, Mauna Kea, Hawaii, USA
    CFHT Interior
    CFHT Telescope, Mauna Kea, Hawaii, USA

    It may provide important clues about how the Solar System formed.

    In a paper* to be published today in the journal Science Advances, lead author Karen Meech of the University of Hawai`i’s Institute for Astronomy and her colleagues conclude that C/2014 S3 (PANSTARRS) formed in the inner Solar System at the same time as the Earth itself, but was ejected at a very early stage.

    Their observations indicate that it is an ancient rocky body, rather than a contemporary asteroid that strayed out. As such, it is one of the potential building blocks of the rocky planets, such as the Earth, that was expelled from the inner Solar System and preserved in the deep freeze of the Oort Cloud for billions of years [1].

    Karen Meech explains the unexpected observation: “We already knew of many asteroids, but they have all been baked by billions of years near the Sun. This one is the first uncooked asteroid we could observe: it has been preserved in the best freezer there is.”

    C/2014 S3 (PANSTARRS) was originally identified by the Pan-STARRS1 telescope as a weakly active comet a little over twice as far from the Sun as the Earth.

    Pann-STARSR1 Telescope
    Pann-STARRS1 interior
    Pann-STARRS1 Telescope, U Hawaii, Mauna Kea, Hawaii, USA

    Its current long orbital period (around 860 years) suggests that its source is in the Oort Cloud, and it was nudged comparatively recently into an orbit that brings it closer to the Sun.

    Oort cloud Image by TypePad, http://goo.gl/NWlQz6
    Oort cloud Image by TypePad, http://goo.gl/NWlQz6

    The team immediately noticed that C/2014 S3 (PANSTARRS) was unusual, as it does not have the characteristic tail that most long-period comets have when they approach so close to the Sun. As a result, it has been dubbed a Manx comet, after the tailless cat. Within weeks of its discovery, the team obtained spectra of the very faint object with ESO’s Very Large Telescope in Chile.

    Careful study of the light reflected by C/2014 S3 (PANSTARRS) indicates that it is typical of asteroids known as S-type, which are usually found in the inner asteroid main belt. It does not look like a typical comet, which are believed to form in the outer Solar System and are icy, rather than rocky. It appears that the material has undergone very little processing, indicating that it has been deep frozen for a very long time. The very weak comet-like activity associated with C/2014 S3 (PANSTARRS), which is consistent with the sublimation of water ice, is about a million times lower than active long-period comets at a similar distance from the Sun.

    The authors conclude that this object is probably made of fresh inner Solar System material that has been stored in the Oort Cloud and is now making its way back into the inner Solar System.

    A number of theoretical models are able to reproduce much of the structure we see in the Solar System. An important difference between these models is what they predict about the objects that make up the Oort Cloud. Different models predict significantly different ratios of icy to rocky objects. This first discovery of a rocky object from the Oort Cloud is therefore an important test of the different predictions of the models. The authors estimate that observations of 50–100 of these Manx comets are needed to distinguish between the current models, opening up another rich vein in the study of the origins of the Solar System.

    Co-author Olivier Hainaut (ESO, Garching, Germany), concludes: “We’ve found the first rocky comet, and we are looking for others. Depending how many we find, we will know whether the giant planets danced across the Solar System when they were young, or if they grew up quietly without moving much.”
    Notes

    [1] The Oort cloud is a huge region surrounding the Sun like a giant, thick soap bubble. It is estimated that it contains trillions of tiny icy bodies. Occasionally, one of these bodies gets nudged and falls into the inner Solar System, where the heat of the sun turns it into a comet. These icy bodies are thought to have been ejected from the region of the giant planets as these were forming, in the early days of the Solar System.

    More information

    *This research was presented in a paper entitled Inner Solar System Material Discovered in the Oort Cloud, by Karen Meech et al., in the journal Science Advances.

    The team is composed of Karen J. Meech (Institute for Astronomy, University of Hawai`i, USA), Bin Yang (ESO, Santiago, Chile), Jan Kleyna (Institute for Astronomy, University of Hawai`i, USA), Olivier R. Hainaut (ESO, Garching, Germany), Svetlana Berdyugina (Institute for Astronomy, University of Hawai’i, USA; Kiepenheuer Institut für Sonnenphysik, Freiburg, Germany), Jacqueline V. Keane (Institute for Astronomy, University of Hawai`i, USA), Marco Micheli (ESA, Frascati, Italy), Alessandro Morbidelli (Laboratoire Lagrange/Observatoire de la Côte d’Azur/CNRS/Université Nice Sophia Antipolis, France) and Richard J. Wainscoat (Institute for Astronomy, University of Hawai`i, USA).

    See the full article here .

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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

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  • richardmitnick 11:08 am on April 29, 2016 Permalink | Reply
    Tags: , , , , The Globe and Mail   

    From The Globe and Mail via PI: “‘Brilliant’ physicist to hold $8-million research chair at Perimeter Institute” 

    Perimeter Institute
    Perimeter Institute

    1

    Apr. 28, 2016
    IVAN SEMENIUK

    Long before the February press conference where physicists reported the first detection of gravitational waves from space – a major scientific achievement that made headlines around the world – Asimina Arvanitaki had arrived at a way to do the same thing with a far smaller and cheaper experiment involving a microscopic disk suspended by powerful lasers.

    The 36-year-old theorist, known to friends and colleagues as Mina, has become a specialist in thinking up novel approaches to some of of the deepest problems in fundamental physics. Her work is at the forefront of an emerging area of research that is sometimes called “the precision frontier” because it involves making exacting measurements of well-understood phenomena and looking for unexpected deviations from what theory predicts.

    “Most of these ideas you can actually build on a table,” said Dr. Arvanitaki.

    Now Dr. Arvanitaki will have more scope and resources to pursue her ideas as the latest recipient of an $8-million research chair at the Perimeter Institute for Theoretical Physics in Waterloo, Ont., where she has worked as a researcher since 2014.

    The new chair is noteworthy for a few reasons. In addition to representing an area of research that thrives on working off the beaten track, Dr. Arvanitaki will become the first female chair holder at the high-profile institute and the first to be supported by a funding source from outside Canada.

    The Stavros Niarchos Foundation, a philanthropic organization headquartered in Athens and associated with a shipping industry fortune, will cover half the cost of the chair with the remaining support coming from the Perimeter Institute.

    Greek heritage is evident in the title of the new position, dubbed the Aristarchus Chair in Theoretical Physics after the ancient philosopher from the Greek island of Samos who famously suggested that the Earth revolves around the sun, some 18 centuries before Nicolaus Copernicus.

    “His thinking implied the sun is exactly like the distant stars,” said Dr. Arvanitaki, who suggested the name for the inaugural chair.

    She added that by foreseeing that our solar system many not be unique in the universe, Aristarchus was also setting the stage for a far more contentious theory in current physics, which holds that our entire universe is just one of many.

    “It’s a very controversial idea. People hate it, but I find it fascinating,” Dr. Arvanitaki said.

    Raised in a small village in southern Greece, Dr. Arvanitaki was the child of two teachers and grew up with an appetite for learning. She recalls that at a young age she correctly calculated the time it takes light to travel from Earth to the sun – about eight minutes – and was stunned to realize that “we cannot know the ‘now’ of the sun.”

    Dr. Arvanitaki came to Perimeter after earning her PhD and doing postdoctoral work at Stanford University under Savas Dimopoulus, a widely respected theorist who also hails from Greece.

    “She’s one of the most brilliant young people I’ve ever met,” Dr. Dimopoulos said of his former student and collaborator.

    He added that intelligence alone was not enough for success in physics, and that one way Dr. Arvanitaki excels is in selecting problems to work on that lead to productive results.

    “You have to have good taste,” he said. “Or in her case, even inventing new directions and new ways to see very well-motivated ideas.”

    Dr. Arvanitaki said she was looking forward to bringing on more researchers and students to accelerate her efforts to explore new domains of physics, and was pleased at the prospect of doing it at the Perimeter Institute. “There’s something about this place – you feel it when you walk in the building – it’s intoxicating.”

    The Institute was established in 1999 by BlackBerry co-founder Mike Lazaridis and has since drawn substantial government support, including a $50-million investment over five years announced in the latest federal budget.

    Black holes merging Swinburne Astronomy Productions
    Black holes merging Swinburne Astronomy Productions

    See the full article here .

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    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 10:55 am on April 29, 2016 Permalink | Reply
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    From NRAO: “Gravitational Wave Search Provides Insights into Galaxy Evolution and Mergers” 

    NRAO Icon
    National Radio Astronomy Observatory

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    5 April 2016
    Elizabeth Ferrara
    NANOGrav press officer
    elizabeth.ferrara@nanograv.org
    301-286-7057

    Charles Blue
    NRAO Public Information Officer
    cblue@nrao.edu
    (434) 296-0314

    1
    The Earth is constantly jostled by low-frequency gravitational waves from supermassive black hole binaries in distant galaxies. Astrophysicists are using pulsars as a galaxy-sized detector to measure the Earth’s motion from these waves. Credit: B. Saxton (NRAO/AUI/NSF)

    Summary: New results from NANOGrav – the North American Nanohertz Observatory for Gravitational Waves – establish astrophysically significant limits in the search for low-frequency gravitational waves. This result provides insight into how often galaxies merge and how those merging galaxies evolve over time. To obtain this result, scientists required an exquisitely precise, nine-year pulsar-monitoring campaign conducted by two of the most sensitive radio telescopes on Earth, the Green Bank Telescope in West Virginia and the Arecibo Observatory in Puerto Rico.

    NRAO/GBT
    NRAO/GBT, West Virginia, USA

    NAIC/Arecibo Observatory
    NAIC/Arecibo Observatory, Puerto Rico, USA

    The recent LIGO detection of gravitational waves from merging black holes with tens of solar masses has confirmed that distortions in the fabric of space-time can be observed and measured [1].

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

    Caltech/MIT Advanced aLIGO Hanford Washington USA installation
    Caltech/MIT Advanced aLIGO Hanford Washington USA installation

    Researchers from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) have spent the past decade searching for low-frequency gravitational waves emitted by black hole binaries with masses many millions of times larger than those seen by LIGO.

    Analysis of NANOGrav’s nine-year dataset provides very constraining limits on the prevalence of such supermassive black hole binaries throughout the Universe. Given scientists’ current understanding of how often galaxies merge, these limits point to fewer detectable supermassive black hole binaries than were previously expected. This result has significant impacts on our understanding of how galaxies and their central black holes co-evolve.

    Low-frequency gravitational waves are very difficult to detect, with wavelengths spanning light-years and originating from black hole binaries in galaxies spread across the sky. The combination of all these giant binary black holes leads to a constant “hum” of gravitational waves that models predict should be detectable at Earth. Astrophysicists call this effect the “stochastic gravitational wave background,” and detecting it requires special analysis techniques.

    Pulsars are the cores of massive stars left behind after stars go supernova. The fastest pulsars rotate hundreds of times each second and emit a pulse of radio waves every few milliseconds. These millisecond pulsars (MSPs) are considered nature’s most precise clocks and are ideal for detecting the small signal from gravitational waves. “This measurement is possible because the gravitational wave background imprints a unique signature onto the radio waves seen from a collection of MSPs,” said Justin Ellis, Einstein Fellow at NASA’s Jet Propulsion Laboratory, California Institute of Technology in Pasadena, California, and a co-author on the report published in Astrophysical Journal.

    Astrophysicists use computer models to predict how often galaxies merge and form supermassive black hole binaries. Those models use several simplifying assumptions about how black hole binaries evolve when they predict the strength of the stochastic gravitational wave background. By using information about galaxy mergers and constraints on the background, the scientists are able to improve their assumptions about black hole binary evolution.

    Ellis continues: “After nine years of observing a collection of MSPs, we haven’t detected the stochastic background but we are beginning to rule out many predictions based on current models of galaxy evolution. We are now at a point where the non-detection of gravitational waves is actually improving our understanding of black hole binary evolution.”

    “Pulsar timing arrays like NANOGrav are making novel observations of the evolution and nature of our Universe,” says Sarah Burke Spolaor, Jansky Fellow at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, and a co-author on the paper.

    According to Spolaor, there are two possible interpretations of this non-detection. “Some supermassive black hole binaries may not be in circular orbits or are significantly interacting with gas or stars. This would drive them to merge faster than simple models have assumed in the past,” she said. An alternate explanation is that many of these binaries inspiral too slowly to ever emit detectable gravitational waves.

    NANOGrav is currently monitoring 54 pulsars, using the National Science Foundation’s Green Bank Telescope in West Virginia and Arecibo Radio Observatory in Puerto Rico, the two most sensitive radio telescopes at these frequencies [2]. Their array of pulsars is continually growing as new MSPs are discovered. In addition, the group collaborates with radio astronomers in Europe and Australia as part of the International Pulsar Timing Array, giving them access to many more pulsar observations. Ellis estimates that this increase in sensitivity could lead to a detection in as little as five years.

    In addition, this measurement helps constrain the properties of cosmic strings, very dense and thin cosmological objects, which many theorists believe evolved when the Universe was just a fraction of a second old. These strings can form loops, which then decay through gravitational wave emission. The most conservative NANOGrav limit on cosmic string tension is the most stringent limit to date, and will continue to improve as NANOGrav continues operating.

    “These new results from NANOGrav have the most important astrophysical implications yet,” said Scott Ransom, an astronomer with the NRAO in Charlottesville, Virginia. “As we improve our detection capabilities, we get closer and closer to that important threshold where the cosmic murmur begins to be heard. At that point, we’ll be able to perform entirely new types of physics experiments on cosmic scales and open up a new window on the Universe, just like LIGO just did for high-frequency gravitational waves.”

    NANOGrav is a collaboration of over 60 scientists at over a dozen institutions in the United States and Canada whose goal is detecting low-frequency gravitational waves to open a new window on the Universe. The group uses radio pulsar timing observations to search for the ripples in the fabric of spacetime. In 2015, NANOGrav was awarded $14.5 million by the National Science Foundation (NSF) to create and operate a Physics Frontiers Center.

    The Physics Frontier Centers bring people together to address frontier science, and NANOGrav’s work in low-frequency gravitational wave physics is a great example,” said Jean Cottam Allen, the NSF program director who oversees the Physics Frontiers Center program. “We’re delighted with their progress thus far, and we’re excited to see where it will lead.”

    1. # #

    Notes

    [1] LIGO is the Laser Interferometer Gravitational-Wave Observatory (https://www.ligo.caltech.edu)
    Press Release: Gravitational waves detected 100 years after Einstein’s prediction http://www.nsf.gov/news/news_summ.jsp?cntn_id=137628&org=NSF&from=news

    [2] National Science Foundation (http://www.nsf.gov)
    Press Release: Advancing physics frontiers: Newest collaborative centers set to blaze trails in basic research
    http://www.nsf.gov/news/news_summ.jsp?cntn_id=134586

    Reference:
    The NANOGrave Nine-year Data Set: Limits on the Isotropic Stochastic Gravitational Wave Background, Z. Arzoumanian et al., 2016, appears in the Astrophysical Journal http://iopscience.iop.org/journal/0004-637X.

    See the full article here .

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    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    ALMA Array

    NRAO ALMA

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    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 8:21 am on April 29, 2016 Permalink | Reply
    Tags: , , brainpickings, Vera Rubin,   

    From brainpickings: “Pioneering Astronomer Vera Rubin on Women in Science, Dark Matter, and Our Never-Ending Quest to Know the Universe” 

    brainpickings bloc

    brainpickings

    4.29.16
    Maria Popova

    Pioneering Astronomer Vera Rubin on Women in Science, Dark Matter, and Our Never-Ending Quest to Know the Universe

    “We’re still groping for the truth… Science consists of continually making better and better what has been usable in the past.”

    When trailblazing astronomer Maria Mitchell was hired to teach at the newly established Vassar College in 1865, she was the only woman on the faculty and according to the original college handbook of rules, female students were not allowed to go outside after dark. Although Mitchell fought to upend this absurd obstruction to the study of astronomy and became a tireless champion of young women in the field, lamentably little changed in the century that followed.

    Exactly one hundred years later, another remarkable observer of the cosmos ushered in a new era both for astronomy itself and for women’s role in it. In 1965, astronomer Vera Rubin (b. July 23, 1928) became the first woman permitted to observe at the Palomar Observatory, home to the most powerful telescopes at the time. So began her pioneering work on galaxy rotation, which precipitated Rubin’s confirmation of the existence of dark matter — one of the most significant milestones in our understanding of the universe. (That Rubin hasn’t yet received a Nobel Prize is a testament to the systemic flaws in how these accolades are meted out.)

    1
    Vera Rubin as an undergraduate at Vassar, 1940s. No image credit

    Nowhere do Rubin’s extraordinary mind and spirit come more alive than in Origins: The Lives and Worlds of Modern Cosmologists (public library) — a magnificent 1990 collection of interviews exploring “the ways in which personal, philosophical, and social factors enter the scientific process” by Alan Lightman and Roberta Brawer, featuring luminaries like Stephen Hawking, Alan Guth, and Martin Rees.

    Like Jane Goodall, who turned her childhood dream into reality, Rubin’s cosmic career began at the very beginning:

    “My childhood bedroom … had a bed which was under windows that faced north. At about age 10, while lying in bed, I started watching the stars just move through the night. By about age 12, I would prefer to stay up and watch the stars than go to sleep. I started learning, going to the library and reading… There was just nothing as interesting in my life as watching the stars every night. I found it a remarkable thing. You could tell time by the stars. I could see meteors.[…]

    When there were meteor showers and things like that, I would not put the light on. Throughout the night I would memorize where each one went so that in the morning I could make a map of their trails.”

    By high school, Rubin knew that she wanted to be an astronomer. But she had never met a single astronomer in real life — she only knew of Maria Mitchell from a children’s book. In a testament to the power of picture-books about cultural icons to offer vitalizing role models and expand children’s scope of possibility, Rubin recounts:

    “I knew that [Maria Mitchell] had taught at Vassar. So I knew there was a school where women could study astronomy… It never occurred to me that I couldn’t be an astronomer.”

    2
    Maria Mitchell. No image credit.

    She followed in Mitchell’s footsteps and went to Vassar, got married to a fellow scientist, and went on to a graduate program at Cornell along with her new husband. Rubin relays a jarring sign of the times:

    “Actually, I had been accepted by Harvard. I have a letter somewhere from [Harvard Observatory director] Donald Menzel saying, “Damn you women,” handwritten across the bottom. This was a response to a letter I wrote saying that I wished to withdraw because I was getting married and going to Cornell. He scribbled across this very formal letter, thanking me for letting him know, something like “Damn you women. Every time I get a good one ready, she goes off and gets married.”

    But marriage didn’t obstruct Rubin’s scientific pursuits, nor did Cornell’s nearly nonexistent astronomy department, which consisted of one man (a former wartime navigator who actively discouraged Rubin from pursuing astronomy) and one woman (who Rubin surmises was the only female faculty member at Cornell at the time). Still, the university offered an unparalleled physics program of which Rubin took advantage. Richard Feynman was on her thesis committee. The actual presentation of her master’s thesis is a poignant parable of both Rubin’s remarkable character and the Sisyphean climb required of women in just about every professional field at the time.

    In December of 1950, 22-year-old Rubin was to present her thesis at the American Astronomical Society. Having just given birth to her first child and nursing the newborn, she made her way through snowy upstate New York, walked into the meeting, gave her 10-minute presentation on galaxy rotation, and left.

    4
    Spiral Galaxy M101 (Image credit: NASA / Hubble Space Telescope)

    The concept of large-scale motion of the universe was a revolutionary one, twenty years ahead of its time, and it garnered the skepticism with which all such visionary ideas are at first received. Rubin’s resulting paper was rejected by the two major astronomy journals of the era. Even the few scientists intrigued by her work were subject to the limiting conventions of the time — the great theoretical physicist and cosmologist George Gamow, who would later become her doctoral advisor, contacted Rubin to inquire about her galaxy rotation work but refused to let her attend his lecture at Georgetown’s Applied Physics Lab “because wives were not allowed” there.

    But Rubin remained driven by the same irrepressible curiosity with which she had peered into the night sky from her childhood bedroom, so she went on with her work, animated by that most powerful of motives — the joy of discovery:

    “Although several times in my career I have found myself in relatively controversial positions, I really don’t enjoy it. For me, doing astronomy is incredibly great fun. It’s just a joy to get up every morning and come to work. In a sense, the heated controversy really spoiled the fun. I mean people were really very harsh. Maybe one learns to take this. I’m not sure you do.

    […]

    I decided to pick a problem that I could go observing and make headway on — hopefully, a problem that people would be interested in, but not so interested in that anyone would bother me before I was done.”

    5
    Vera Rubin in 1974. No image credit.

    “That problem was dark matter, the existence of which Rubin set out to prove through observation. At the time, it was still a theoretical construct, regarded as rather inconvenient in the context of existing theories:

    Many people initially wished that you didn’t need dark matter. It was not a concept that people embraced enthusiastically. But I think that the observations were undeniable enough so that most people just unenthusiastically adopted it.”

    Today, dark matter has become not only accepted but central to our understanding of the universe and even of our own existence. Its story is a testament to the most perennial truth of science and human knowledge, as well as to the fact that a great scientist is always more interested in understanding than in being right, both of which Rubin captures beautifully:

    “We’re still groping for the truth. So I don’t really worry too much about details that don’t fit in, because I put them in the domain of things we still have to learn about. I really see no reason why we should have been lucky enough to live at the point where the universe was understood in its totality… As telescopes get bigger, and astronomers get cleverer, I think all kinds of things are going to be discovered that are going to require alterations in our theories… Science consists of continually making better and better what has been usable in the past.”

    I’m reminded of Marie Curie, hunched over in her lab long before the first of her two Nobel Prizes, asserting in a letter to her brother that “one never notices what has been done; one can only see what remains to be done.” Amid our age of productivity, this might sound like a dispiriting sentiment — but to the scientist ablaze with curiosity, it is a source of invigoration. Indeed, one of the most wonderful aspects of science is how inherently unproductive it is — each new discovery illuminates a new frontier of curiosity, each new known unravels a myriad new unknowns, and the measure of good science is the willingness to reach for that unknown, even if it means recalibrating our present knowns.

    Rubin captures this wonderfully:

    “I hope 500 years from now astronomers still aren’t talking about the same big bang model. I think they won’t have done their work if they are… I still believe there may be many really fundamental things about the universe that we don’t know. I think our ignorance is greater than our knowledge. I wouldn’t put us at the 50-50 point of knowledge about the universe.”

    5
    Cat’s Eye Nebula (Image credit: NASA / Hubble Space Telescope)

    Rubin considers the question of beauty and how it frames our direction of interest. In a sentiment that calls to mind Susan Sontag on beauty vs. interestingness and Frida Kahlo on how affection amplifies beauty, Rubin reflects:

    “I sometimes ask myself whether I would be studying galaxies if they were ugly. I really do, and I’m not sure. I see ugly bugs. My garden is full of slugs. I sometimes think, well, maybe if I started studying them, they wouldn’t appear to be so ugly… I put that at the other extreme. I think it may not be irrelevant that galaxies are really very attractive.”

    She revisits the question of gender and considers what prevented many other women in her generation, and even in her daughter’s generation, from going into science — the same concern with which a little girl once turned to Albert Einstein. Rubin reflects:

    “It’s the way we raise little girls. It happens very early. I think also it’s what little girls see in the world around them. It’s an incredible cultural thing. I have two granddaughters. One of them — her mother and father are both professionals, her aunt and uncle are professionals — said her toy rabbit was sick. Her uncle said, “Well, you be the doctor and I’ll be the nurse, and we’ll fix it,” and she said, “Boys can’t be girls.” And her mother realized that she never had seen a doctor who was a woman. By the age of 2, she knew that men were doctors and women were nurses. So you may talk about role models and your thinking about colleges, but this happens at the age of 2. It’s a very complicated situation.”

    Rubin — who has three sons and one daughter, all with doctorates in science — argues that the only viable solution to this systemic problem lies in raising little girls with enough confidence to pursue their interests and withstand the limiting cultural messages about what they can and cannot be. She recounts her own conquest of the odds:

    “I went to a D.C. public high school. I was very, very interested in astronomy, and I just could keep myself going by telling myself that I was just different than other people, that they just had different interests than I did. I had a physics teacher who was a real macho guy. Everybody loved him — all the males. He did experiments; he set up labs. Everybody was very enthusiastic. I really don’t think he knew how to relate to a young girl in his class… He never knew that I was interested in astronomy, he never knew that I was interested in science. The day I learned I got my scholarship to Vassar, I was really excited because I couldn’t go to college without a scholarship. I met him in the hall, and probably said the first thing I had ever said to him outside of the class, and I told him I got the scholarship to Vassar, and he said to me, “As long as you stay away from science, you should do okay.” It takes an enormous self-esteem to listen to things like that and not be demolished. So rather than teaching little girls physics, you have to teach them that they can learn anything they want to.”

    How pause-giving to consider that science progresses much more rapidly than the cultural norms of science do. In the generation between Rubin and her daughter, who is also an astronomer, we have discovered cosmic microwave background radiation, decoded the molecular structure of DNA, and invented lasers, and yet the gender ration of science hasn’t improved nearly enough, nor has the subtle cultural messaging. What Rubin recounts a quarter century ago is still the basic reality in many rooms and in many parts of the world:

    “My daughter is an astronomer. She got her Ph.D. in cosmic ray physics and went off to a meeting in Japan, and she came back and told me she was the only woman there. I really couldn’t tell that story for a long time without weeping, because certainly in one generation, between her generation and mine, not an awful lot has changed. Some things are better, but not enough things.”

    What a poignant slogan for all human rights movements, from racial justice to marriage equality: “Some things are better, but not enough things.” And yet, like Curie, we can see this not as a lamentation but as a frontier of hope — because “what remains to be done” can be done, and it falls on us to do it.

    Complement the altogether wonderful Origins, which Carl Sagan lauded as a skillful “exposition of the styles of scientific thinking,” with Vera Rubin on obsessiveness and uncertainty and her terrific 1996 Berkeley commencement address.

    See the full article here .

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  • richardmitnick 7:32 am on April 29, 2016 Permalink | Reply
    Tags: , , , Webb's mirror unveiled   

    From Goddard: “James Webb Space Telescope’s Golden Mirror Unveiled” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    April 27, 2016
    Laura Betz
    NASA Goddard Space Flight Center

    NASA engineers recently unveiled the giant golden mirror of NASA’s James Webb Space Telescope as part of the integration and testing of the infrared telescope.

    1
    Standing tall and glimmering gold inside NASA’s Goddard Space Flight Center’s clean room in Greenbelt, Maryland is the James Webb Space Telescope primary mirror. It will be the largest yet sent into space. Credits: NASA/Chris Gunn

    The 18 mirrors that make up the primary mirror were individually protected with a black covers when they were assembled on the telescope structure. Now, for the first time since the primary mirror was completed, the covers have been lifted.

    Standing tall and glimmering gold inside NASA’s Goddard Space Flight Center’s clean room in Greenbelt, Maryland, this mirror will be the largest yet sent into space. Currently, engineers are busy assembling and testing the other pieces of the telescope.

    Scientists from around the world will use this unique observatory to capture images and spectra of not only the first galaxies to appear in the early universe over 13.5 billion years ago, but also the full range of astronomical sources such as star forming nebulae, exoplanets, and even moons and planets within our own Solar System. To ensure the mirror is both strong and light, the team made the mirrors out of beryllium. Each mirror segment is about the size of a coffee table and weighs approximately 20 kilograms (46 pounds). A very fine film of vaporized gold coats each segment to improve the mirror’s reflection of infrared light. The fully assembled mirror is larger than any rocket so the two sides of it fold up. Behind each mirror are several motors so that the team can focus the telescope out in space.

    This widely anticipated telescope will soon go through many rigorous tests to ensure it survives its launch into space. In the next few months, engineers will install other key elements, and take additional measurements to ensure the telescope is ready for space.

    The James Webb Space Telescope is the scientific successor to NASA’s Hubble Space Telescope.

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

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    It will be the most powerful space telescope ever built. Webb will study many phases in the history of our universe, including the formation of solar systems capable of supporting life on planets similar to Earth, as well as the evolution of our own solar system. It’s targeted to launch from French Guiana aboard an Ariane 5 rocket in 2018. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

    See the full article here.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

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