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    VIRGOCosmos In Brief - Aktualní novinky vesmírného výzkumu v kostce
    VIRGO
    VIRGO --- ---
    Most images of black holes are illustrations. Here’s what our telescopes actually capture. - Vox
    https://www.vox.com/science-and-health/2018/1/8/16822272/black-hole-looks-like-what/

    Most images of black holes are illustrations. This soon may change. An audacious global project called
    the Event Horizon Telescope is currently working to piece together an image of a black hole for the first time.

    VIRGO
    VIRGO --- ---
    Hurá!!

    První segmenty primárního zrcadla dalekohledu ELT úspěšně odlity | ESO Česko
    http://www.eso.org/public/czechrepublic/news/eso1801/?lang

    Německá firma SCHOTT ve své továrně ve městě Mainz úspěšně odlila prvních šest segmentů primárního zrcadla pro dalekohled ELT. Hlavní zrcadlo dalekohledu ELT bude
    mít průměr 39 m a bude ho tvořit celkem 798 šestiúhelníkových segmentů. Po dokončení v roce 2024 by se dalekohled ELT měl stát největším optickým teleskopem na světě.

    Primární zrcadlo připravovaného dalekohledu ELT (Extremely Large Telescope) bude s průměrem 39 m zdaleka největším, jaké bylo kdy osazeno v jakémkoliv dalekohledu
    pro viditelnou nebo infračervenou oblast. Takto velké zrcadlo je však příliš velké na to, aby bylo možné ho vyrobit z jednoho kusu skla. Proto bude sestaveno ze 798
    šestiúhelníkových segmentů o průměru 1,4 m a tloušťce 5 cm. Jednotlivé díly budou uloženy tak, aby mohly pracovat společně jako jedna optická plocha, která posbírá
    dvacetmilionkrát více světla než lidské oko.

    ESOcast Light 145: First ELT Main Mirror Segments Successfully Cast
    https://www.youtube.com/watch?v=85Qcbn8nlaM
    VIRGO
    VIRGO --- ---
    First PEPSI data release — English
    http://www.aip.de/en/news/science/first-pepsi-data-release

    The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona
    released its first batch of high-spectral resolution data to the scientific community. In a series of three papers in
    the European journal Astronomy & Astrophysics, the PEPSI team presents a new spectral atlas of the Sun, a total of 48
    atlases of bright benchmark stars, and a detailed analysis of the chemical abundances of the 10-billion year old planet-
    system host Kepler-444.

    VIRGO
    VIRGO --- ---
    Saturn's moon Titan sports Earth-like features | Cornell Chronicle
    http://news.cornell.edu/stories/2018/01/saturns-moon-titan-sports-earth-features

    Using the now-complete Cassini data set, Cornell astronomers have created a new global topographic map of Saturn’s moon Titan that has opened new windows into
    understanding its liquid flows and terrain. Two new papers, published Dec. 2 in Geophysical Review Letters, describe the map and discoveries arising from it.

    Creating the map took about a year, according to doctoral student Paul Corlies, first author on “Titan’s Topography and Shape at the End of the Cassini Mission.”
    The map combines all of the Titan topography data from multiple sources. Since only about 9 percent of Titan has been observed in relatively high-resolution
    topography, with 25-30 percent of the topography imaged in lower resolution, the remainder of the moon was mapped using an interpolation algorithm and a global
    minimization process, which reduced errors such as those arising from spacecraft location.

    The map revealed several new features on Titan, including new mountains, none higher than 700 meters. The map also provides a global view of the highs and lows
    of Titan’s topography, which enabled the scientists to confirm that two locations in the equatorial region of Titan are in fact depressions that could be either
    ancient, dried seas or cryovolcanic flows. The map also revealed that Titan is a little bit flatter – more oblate – than was previously known, which suggests
    there is more variability in the thickness of Titan’s crust than previously thought.
    VIRGO
    VIRGO --- ---
    https://www.nasa.gov/image-feature/jpl/pia21901/veil-of-ice

    Saturn’s rings, made of countless icy particles, form a translucent veil in this view from NASA’s Cassini spacecraft.

    Saturn’s tiny moon Pan, about 17 miles (28 kilometers) across, orbits within the Encke Gap in the A ring. Beyond,
    we can see the arc of Saturn itself, its cloud tops streaked with dark shadows cast by the rings.

    This image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 12, 2016, at a distance
    of approximately 746,000 miles (1.2 million kilometers) from Pan.

    VIRGO
    VIRGO --- ---
    W. M. Keck Observatory Achieves First Light with NIRES W. M. Keck Observatory
    http://www.keckobservatory.org/recent/entry/NIRES

    Astronomers at W. M. Keck Observatory have successfully met a major milestone after capturing the very first
    science data from Keck Observatory’s newest instrument, the Caltech-built Near-Infrared Echellette Spectrometer (NIRES).

    The Keck Observatory-Caltech NIRES team just completed the instrument’s first set of commissioning observations and achieved
    “first light” with a spectral image of the planetary nebula NGC 7027.

    “The Keck Observatory continually strives to provide instrumentation that meets the high aspirations of our scientific
    community and responds to changing scientific needs,” said Keck Observatory Director Hilton Lewis. “NIRES is expected to be
    one of the most efficient single-object, near-infrared spectrographs on an eight to ten-meter telescope, designed to study
    explosive, deep sky phenomena such as supernovae and gamma ray bursts, a capability that is in high demand.”

    “The power of NIRES is that it can cover a whole spectral range simultaneously with one observation,” said Keith Matthews,
    the instrument’s principal investigator and a chief instrument scientist at Caltech. “It’s a cross-dispersed spectrograph
    that works in the infrared from where the visual cuts off out to 2.4 microns where the background from the thermal emission
    gets severe.”

    VIRGO
    VIRGO --- ---
    Large asteroid 2018 AH flew past Earth at 0.77 LD, 2 days after discovery

    A relatively large newly discovered asteroid designated 2018 AH flew past Earth at 0.77 LD / 0.00199 AU (~297 699 km / 184 982 miles) on January 2, 2018.
    This is the 1st known asteroid to flyby Earth within 1 LD this year, 54th since January 1, 2017 and the largest within 1 LD since 2011.

    2018 AH was first observed at ATLAS-MLO, Mauna Loa on January 4, 2018, two days after its close approach to Earth. The closest approach to Earth took place
    at 04:25 UTC on January 2 at a speed (relative to the Earth) of 13.76 km/s.

    It belongs to the Apollo group of asteroids, the most common one, and it has an estimated diameter of 84 - 190 m (275 - 693 feet), making it the largest
    known near-Earth object to flyby Earth within 1 lunar distance since 2011.

    It is also the 9th largest known near-Earth object (asteroids + comets) to flyby Earth within 1 lunar distance ever. Over the past 18 years, only 2 asteroids
    larger than 2018 AH flew past us this close and 8 since 1918.

    As of January 5, 2018, there are 17 566 known near-Earth objects around our planet, 17 460 of them are asteroids. Of the total number of known NEOs,
    7 999 have an estimated diameter roughly 140 m (460 feet) or larger, including 2018 AH.

    VIRGO
    VIRGO --- ---
    Gravitational Waves Measure the Universesu201801 | www.cfa.harvard.edu/
    https://www.cfa.harvard.edu/news/su201801

    The direct detection of gravitational waves from at least five sources during the past two years offers spectacular confirmation of Einstein's model of gravity and space-time. Modeling of these events has also
    provided information on massive star formation, gamma-ray bursts, neutron star characteristics, and (for the first time) verification of theoretical ideas about how the very heavy elements, like gold, are produced.

    Astronomers have now used a single gravitational wave event (GW170817) to measure the age of the universe. CfA astronomers Peter Blanchard, Tarreneh Eftekhari, Victoria Villar, and Peter Williams were members
    of a team of 1314 scientists from around the world who contributed to the detection of gravitational waves from a merging pair of binary neutron stars, followed by the detection of gamma-rays, and then the
    identification of the origin of the cataclysm in a source in the galaxy NGC4993 spotted in images taken with various time delays at wavelengths from the X-ray to the radio.

    An analysis of the gravitational waves from this event infers their intrinsic strength. The observed strength is less, implying (because the strength diminishes with distance from the source) that the source
    is about 140 million light-years away. NGC4993, its host galaxy, has an outward velocity due to the expansion of the universe that can be measured from its spectral lines. Knowing how far away it is and how fast
    the galaxy is moving from us allows scientists to calculate the time since the expansion began – the age of the universe: between about 11.9 and 15.7 billion years given the experimental uncertainties.

    VIRGO
    VIRGO --- ---
    Plot thickens as New Horizons moves within year of next flyby – Astronomy Now
    https://astronomynow.com/2018/01/06/plot-thickens-as-new-horizons-moves-within-year-of-next-flyby/

    The final days before NASA’s New Horizons probe barrels in on its next destination on Jan. 1, 2019, should prove eventful, with scientists trying
    to sort out whether a distant mini-world detected by the Hubble Space Telescope more than three years ago may actually be a swarm of icy objects.

    New Horizons’ sharp-eyed camera will serve as a look-out as the spacecraft makes a speedy approach toward 2014 MU69, the official name for the mission’s
    next target. Scientists will search for moons and icy debris, discoveries which could add intrigue to the one-shot encounter on New Year’s Day 2019.

    BLACKHEAD
    BLACKHEAD --- ---
    VIRGO: To vypada (podle tech ryh) jako kus zkameneleho bahna...
    VIRGO
    VIRGO --- ---
    Krásný kousek!

    NASA rover spots strange 'stick-like figures' on Mars - CNET
    https://www.cnet.com/au/news/nasa-mars-rover-curiosity-stick-like-figures-crystals/

    While the rest of us were on vacation over the holidays, the Mars Curiosity rover kept plugging away at its mission of exploring the Red Planet. It put some of the time
    into inspecting and photographing a set of fascinating stick-like formations on the Martian ground. The rover team tweeted a good look at the small objects on Wednesday.

    VIRGO
    VIRGO --- ---
    https://www.nasa.gov/image-feature/jpl/pia21973/high-above-jupiter-s-clouds

    NASA’s Juno spacecraft was a little more than one Earth diameter from Jupiter when it captured this mind-bending, color-enhanced view of the planet’s tumultuous atmosphere.

    Jupiter completely fills the image, with only a hint of the terminator (where daylight fades to night) in the upper right corner, and no visible limb (the curved edge of the planet).

    Juno took this image of colorful, turbulent clouds in Jupiter’s northern hemisphere on Dec. 16, 2017 at 9:43 a.m. PST (12:43 p.m. EST) from 8,292 miles (13,345 kilometers) above
    the tops of Jupiter’s clouds, at a latitude of 48.9 degrees. The spatial scale in this image is 5.8 miles/pixel (9.3 kilometers/pixel).

    Citizen scientists Gerald Eichstädt and Seán Doran processed this image using data from the JunoCam imager.

    VIRGO
    VIRGO --- ---
    ESA Science & Technology: Gaia data help prepare for a rare celestial alignment of Neptune's largest moon
    http://sci.esa.int/...ia-data-help-prepare-for-a-rare-celestial-alignment-of-neptune-s-largest-moon/

    On 5 October 2017, the largest moon of Neptune will pass in front of a distant star. This rare event will temporarily block the star's light from Earth and provide
    an excellent opportunity to study the moon's intriguing atmosphere. Data from ESA's Gaia mission is allowing astronomers to precisely plan their observations.

    VIRGO
    VIRGO --- ---
    How I discovered the origins of the cigar-shaped alien 'asteroid' 'Oumuamua
    https://theconversation.com/...covered-the-origins-of-the-cigar-shaped-alien-asteroid-oumuamua-89577

    With a hyperbolic trajectory around the Sun, `Oumuamua is the first confirmed interstellar object. However, its origin is poorly known. By simulating the orbits of 0.23 million local stars,
    we find 109 encounters with periastron less than 5 pc. `Oumuamua's low peculiar velocity is suggestive of its origin from a young stellar association with similar velocity. In particular,
    we find that `Oumuamua would have had slow encounters with at least five young stars belonging to the Local Association thus suggesting these as plausible sites for formation and ejection.
    In addition to an extremely elongated shape, the available observational data for `Oumuamua indicates a red colour suggestive of a potentially organic-rich and activity-free surface.

    [1711.08800] `Oumuamua as a messenger from the Local Association
    https://arxiv.org/abs/1711.08800

    VIRGO
    VIRGO --- ---
    https://www.nasa.gov/feature/spend-next-new-year-s-eve-with-new-horizons

    In just under a year – shortly after midnight Eastern Time on Jan. 1, 2019 – NASA’s New Horizons spacecraft will buzz by the most primitive and most distant object ever explored.
    New Horizons’ encounter with Kuiper Belt object 2014 MU69, which orbits a billion miles beyond Pluto, will offer the first close-up look at such a pristine building block of
    the solar system – and will be performed in a region of deep space that was practically unknown just a generation ago.

    VIRGO
    VIRGO --- ---
    Library of galaxy histories reconstructed from motions of stars | Instituto de Astrofísica de Andalucía - CSIC
    http://www.iaa.es/en/news/library-galaxy-histories-reconstructed-motions-stars

    The CALIFA survey allows to map the orbits of the stars of a sample of 300 galaxies, a fundamental information to know how they formed and evolved.

    Just like the Sun is moving in our Galaxy, the Milky Way, all the stars in galaxies are moving, but with very different orbits: some of the stars have strong rotations,
    while others may be moving randomly with no clear rotation. Comparing the fraction of stars on different orbits we can find out how galaxies form and evolve. An international
    team of astronomers has derived directly, for the first time, the orbital distribution of a galaxy sample, containing more than 300 galaxies of the local universe. The results,
    published in Nature Astronomy, are based on the CALIFA survey, a project developed at Calar Alto Observatory and conceived from the Institute of Astrophysics of Andalusia.

    Galaxies are largest structures in the universe, and scientist study how they evolve to understand the history of the universe. Galaxy formation entails the hierarchical
    assembly of halos of dark matter (a type of matter that has not been directly observed and whose existence and properties are inferred from its gravitational effects), along
    with the condensation of normal matter at the halos´ center, where stellar formation takes place. Stars that formed from a settled, thin gas disk and then lived though dynamically
    quiescent times will present near circular orbits, while stars with random motions are the result of turbulent environments, either at birth or later, with galactic mergers.

    Proyecto CALIFA: arqueología galáctica en 3D
    https://www.youtube.com/watch?v=w67yS68qwto


    Thus, the motions of stars in a galaxy are like a history book, they record the information about their birth and growth environment, and it may tell us how the galaxy was formed.
    "However, the motion of each single star is not directly observable in external galaxies. External galaxies are projected on the observational plane as an image and we cannot resolve
    the discrete stars in it -says Ling Zhu, researcher from the Max Planck Institute for Astronomy who leads the study-. The CALIFA survey uses a recently developed technique, integral
    field spectroscopy, which can observe the external galaxies in such a way that it provides the overall motion of stars. Thus, we can get kinematic maps of each galaxy."

    The researchers then build models for each galaxy by superposing stars on different types of orbits. By constraining the model with the observed image and kinematic maps, they can
    find out the amount of stars moving on different types of orbits in each galaxy. They call it the stellar orbit distribution and, for this study, the team has built models for all
    300 galaxies, representative of the general properties of galaxies in the local universe.

    VIRGO
    VIRGO --- ---
    Pardon, je to delší, ale odpověď v komentu je také zajímavá.

    How Fast Is Dark Matter?
    http://aasnova.org/2018/01/02/how-fast-is-dark-matter/

    Our galaxy is embedded in a cloud of dark matter, thought to consist of tiny particles traveling along orbits through the halo. These dark matter particles permeate all regions of the galaxy,
    extending far beyond the edge of the bright central spiral, but also orbiting through our solar system, and even passing right through the Earth. This is why scientists build giant detectors,
    hoping to trap some of these dark matter particles as they pass by. So far, these experiments have not detected dark matter, but that lack of detection is actually quite interesting. Finding
    out what dark matter is not, and thereby narrowing down the possibilities, is an important step towards revealing the true nature of these mysterious particles.

    In order to really understand what it means when a detecter does not see dark matter, it is important to have a clear prediction for how much dark matter should be detected. For example, if we
    expect very few dark matter particles to pass through the Earth in a given amount of time, then maybe the lack of detections over a few years doesn’t actually mean those particles don’t exist.
    One essential piece of information in this prediction is the velocity of dark matter particles as they orbit past our solar system.

    So, how can we determine the speed of these particles that we haven’t even directly detected? Well, let’s look back at where these particles actually come from. Dark matter halos grow over time
    by consuming other dark matter halos. This process is called hierarchical structure formation. The Milky Way is continuously pulling in smaller galaxies and then tearing them apart, thoroughly
    mixing their stars and dark matter particles into the Milky Way halo (Figure 1).

    This understanding of the origin of these particles reveals an important piece of information: when dark matter particles join the Milky Way, they are often accompanied by stars. This is great
    news, because stars, unlike dark matter particles, are not invisible, and we can directly measure their velocities. If we can confirm that dark matter particles tend to move at similar
    velocities to their stellar companions, then this problem of determining the local dark matter velocity is much simpler!



    Odpověď: Chris Reeves (jde o citaci)

    ... in some ways, the discoveries made in recent decades have raised as many new questions as they have answered.

    One of the most vexing gets at the heart of what our universe is actually made of. Cosmological observations have determined the average density of matter
    in our universe to very high precision. But this density turns out to be much greater than can be accounted for with ordinary atoms.

    After decades of measurements and debate, we are now confident that the overwhelming majority of our universe's matter -- about 84 percent -- is not made
    up of atoms, or of any other known substance. Although we can feel the gravitational pull of this other matter, and clearly tell that it's there, we simply
    do not know what it is. This mysterious stuff is invisible, or at least nearly so. For lack of a better name, we call it 'dark matter.' But naming something
    is very different from understanding it.

    For almost as long as we've known that dark matter exists, physicists and astronomers have been devising ways to try to learn what it's made of. They've built
    ultra-sensitive detectors, deployed in deep underground mines, in an effort to measure the gentle impacts of individual dark matter particles colliding with atoms.

    They've built exotic telescopes -- sensitive not to optical light but to less familiar gamma rays, cosmic rays and neutrinos -- to search for the high-energy
    radiation that is thought to be generated through the interactions of dark matter particles.

    And we have searched for signs of dark matter using incredible machines which accelerate beams of particles -- typically protons or electrons -- up to the highest
    speeds possible, and then smash them into one another in an effort to convert their energy into matter. The idea is these collisions could create new and exotic
    substances, perhaps including the kinds of particles that make up the dark matter of our universe.

    As recently as a decade ago, most cosmologists -- including myself -- were reasonably confident that we would soon begin to solve the puzzle of dark matter.
    After all, there was an ambitious experimental program on the horizon, which we anticipated would enable us to identify the nature of this substance and to begin
    to measure its properties. This program included the world's most powerful particle accelerator -- the Large Hadron Collider – as well as an array of other new
    experiments and powerful telescopes.

    But things did not play out the way that we expected them to. Although these experiments and observations have been carried out as well as or better than we could
    have hoped, the discoveries did not come.

    Over the past 15 years, for example, experiments designed to detect individual particles of dark matter have become a million times more sensitive, and yet no signs
    of these elusive particles have appeared. And although the Large Hadron Collider has by all technical standards performed beautifully, with the exception of the Higgs
    boson, no new particles or other phenomena have been discovered.

    The stubborn elusiveness of dark matter has left many scientists both surprised and confused. We had what seemed like very good reasons to expect particles of dark
    matter to be discovered by now. And yet the hunt continues, and the mystery deepens.

    In many ways, we have only more open questions now than we did a decade or two ago. And at times, it can seem that the more precisely we measure our universe,
    the less we understand it. Throughout the second half of the 20th century, theoretical particle physicists were often very successful at predicting the kinds of
    particles that would be discovered as accelerators became increasingly powerful. It was a truly impressive run.

    But our prescience seems to have come to an end -- the long-predicted particles associated with our favorite and most well-motivated theories have stubbornly refused
    to appear. Perhaps the discoveries of such particles are right around the corner, and our confidence will soon be restored. But right now, there seems to be little
    support for such optimism.

    In response, droves of physicists are going back to their chalkboards, revisiting and revising their assumptions. With bruised egos and a bit more humility, we are
    desperately attempting to find a new way to make sense of our world."


    That last sentence is really kind of peculiar. Where are these "droves of physicists" who are "going back to their chalkboards"?

    I'm having trouble seeing them.
    VIRGO
    VIRGO --- ---
    The Geometry of Nuclear Black Hole Accretion Diskssu201750 | www.cfa.harvard.edu/
    https://www.cfa.harvard.edu/news/su201750

    CfA astronomer Anna Pancoast and a team of her colleagues analyzed reverberation mapping data of four AGN to study their geometries and, in particular,
    the volume of hot gas known for its rapid motions, the so-called broad line region because the spectral lines have widths corresponding to as much as
    three thousand kilometers per second. The scientists find the geometry of this gas, at least in these four AGN, is well-described as coming from thick
    disks seen nearly face-on, with median radii from about 1600 AU to 4000 AU, and each with a black hole whose mass is about seventy million solar-masses
    (with an estimated precision for each one of about 50%). The new work was successful in modeling the observations and nearly doubles the size of the AGN
    sample modeled with this technique. The sample is still small, however, and more observations are being planned.

    VIRGO
    VIRGO --- ---
    Alien megastructure not the cause of dimming of the 'most mysterious star in the universe'
    https://phys.org/news/2018-01-alien-megastructure-dimming-mysterious-star.html

    A team of more than 200 researchers, including Penn State Department of Astronomy and Astrophysics Assistant Professor Jason Wright and led by Louisiana State University's
    Tabetha Boyajian, is one step closer to solving the mystery behind the "most mysterious star in the universe." KIC 8462852, or "Tabby's Star," nicknamed after Boyajian, is
    otherwise an ordinary star, about 50 percent bigger and 1,000 degrees hotter than the Sun, and about than 1,000 light years away. However, it has been inexplicably dimming
    and brightening sporadically like no other. Several theories abound to explain the star's unusual light patterns, including that an alien megastructure is orbiting the star.

    he mystery of Tabby's Star is so compelling that more than 1,700 people donated over $100,000 through a Kickstarter campaign in support of dedicated ground-based telescope
    time to observe and gather more data on the star through a network of telescopes around the world. As a result, a body of data collected by Boyajian and colleagues in
    partnership with the Las Cumbres Observatory is now available in a new paper in The Astrophysical Journal Letters.

    "We were hoping that once we finally caught a dip happening in real time we could see if the dips were the same depth at all wavelengths. If they were nearly the same, this
    would suggest that the cause was something opaque, like an orbiting disk, planet, or star, or even large structures in space" said Wright, who is a co-author of the paper,
    titled "The First Post-Kepler Brightness Dips of KIC 8462852." Instead, the team found that the star got much dimmer at some wavelengths than at others.

    "Dust is most likely the reason why the star's light appears to dim and brighten. The new data shows that different colors of light are being blocked at different intensities.
    Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure," Boyajian said.

    VIRGO
    VIRGO --- ---
    Supermassive black holes control star formation in large galaxies
    https://news.ucsc.edu/2018/01/supermassive-black-holes.html

    Astronomers find close correlation between the mass of a galaxy's central black hole and its star formation history

    Young galaxies blaze with bright new stars forming at a rapid rate, but star formation eventually shuts down as a galaxy evolves. A new study, published
    January 1, 2018, in Nature, shows that the mass of the black hole in the center of the galaxy determines how soon this "quenching" of star formation occurs.

    Every massive galaxy has a central supermassive black hole, more than a million times more massive than the sun, revealing its presence through its gravitational
    effects on the galaxy's stars and sometimes powering the energetic radiation from an active galactic nucleus (AGN). The energy pouring into a galaxy from an active
    galactic nucleus is thought to turn off star formation by heating and dispelling the gas that would otherwise condense into stars as it cooled.

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