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    VIRGOCosmos In Brief - Aktualní novinky vesmírného výzkumu v kostce
    VIRGO
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    Superfast Camera Sees Shockwave From Light - IEEE Spectrum
    http://spectrum.ieee.org/...-talk/semiconductors/optoelectronics/superfast-camera-watches-light-move

    A camera system that capture a snapshot of overlapping light waves in a tiny fraction of a second could lead to new
    methods for imaging, allowing scientists to watch the brain’s neurons interacting or see neutrinos colliding with matter.

    The camera system took snapshots at a rate of 100 billion frames per second, fast enough to capture a pulse of laser light
    spreading out in a Mach cone, the optical equivalent of the sonic boom created by an airplane traveling faster than
    the speed of sound.

    VIRGO
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    Velká radost!! "Rhysy" má další publikovanou práci jako hlavní autor (mmjn s panem Paloušem a Jáchymem mezi spoluautory!).
    [1701.05361] Kinematic clues to the origins of starless HI clouds : dark galaxies or tidal debris ?
    https://arxiv.org/abs/1701.05361
    Kéž by to bylo inspirací pro další zdejší mladé osobnosti. Pardon, tohle bude delší...

    So here it is, my eighth paper as first author. It's very similar to the sixth, except that it's much better because it's half as long.
    I'll have a detailed blog post up in a few days, but for now here's the super-short version.

    Most neutral hydrogen gas (HI, pronounced H-one) is associated with optically bright galaxies, but there are a few weird gas clouds that aren't.
    In particular, there are these six HI blobs in the Virgo cluster that look like they're rotating as fast as massive galaxies - but optically they're dark.
    They're miles and miles away from any other galaxies and there's no sign of any extended HI streams anywhere nearby. So the most obvious explanation -
    that they were just ripped out of ordinary galaxies as they fly past each other - has problems.

    What's particularly weird about these clouds is their apparent rotation. We don't really measure rotation directly, just how fast the gas is moving along
    the line of sight. The difference between the fastest and slowest-moving gas gives us a line width, which for normal galaxies it's safe to assume represents
    rotation. If that's the case for these clouds, they need a fairly substantial dark matter halo to hold them together, because they're rotating so fast that
    their gas mass is nowhere near large enough to stop them flying apart. They would effectively be galaxies without any stars.

    But they might not be rotating at all. It's possible the high line widths are really just due to streaming motions with the gas flowing at different velocities
    in the same direction. Other people have claimed from numerical simulations that this explanation works well for some other, similar features. And it does.
    The problem is this has been widely taken to mean that's definitely the best explanation for any and all HI clouds in any situation.

    To test this, we numerically simulated a spiral galaxy falling into a cluster. The target spiral is based on a fairly typical known object and we varied its
    parameters quite a lot to see how much difference that made (and also its trajectory through the cluster). The spiral has gas, stars, and dark matter. The galaxy
    cluster is much simpler : 400 point masses all buzzing around just like in a real cluster. Those point masses just have gravity - they don't have their own gas
    and stars because that's computationally very demanding indeed. This is a big improvement on the earlier works though, because they just did one point mass flying
    past a target galaxy.

    What we show here is that the tidal debris/streaming motion hypothesis categorically, decisively, does not work for objects like these clouds. I would even go so
    far as to say it fundamentally cannot work. It's easy enough to make large clouds with high velocity widths, but's damn near impossible for clouds as small as
    those we see in Virgo. We saw gas being torn off the galaxies into long streams, and those streams get "harassed" into small clouds, which is nice... but there's
    a problem. The greater the streaming motions within a stream, the harder they are to detect and the quicker they disperse. It's incredibly difficult to disperse
    the rest of the stream while preserving the features of the highest velocity widths.

    We also examined the formation mechanism of the famous VIRGOHI21. This well-known dark galaxy candidate is a very sharp "kink" in the velocity of a long stream
    from a spiral galaxy, which again looks like it might be rotating. This is what earlier works were trying to reproduce. We show that actually they didn't really
    do this, even though they claimed to, but our simulations did. That might sound like petty bickering, and it is. But it's important because we can now very clearly
    say if a cloud is likely to be tidal debris or not. If it's in a stream, then that's probably a good explanation. If it's isolated, then that's only a sensible
    explanation if the cloud is rather large or has a low velocity width. If it's isolated but small and with a high velocity width, tidal debris is a lousy explanation.

    As for VIRGOHI21 itself, I would say that after more than a decade, jury's still out. Much to my annoyance, and despite lengthy explanations in the paper, I wasn't
    able to convince the referee that we don't really understand it. It's true that we can explain the velocity kink... but that's all we can explain. We can't easily
    account for the rest of the features of the system, and we haven't really tested the dark galaxy hypothesis - so we don't know how well that explanation actually
    works. Despite the referee's abject protestations that "any scientist" should know that the success of one model not preclude the success of another, they fell for
    this very same fallacy when I added in a footnote about the alternative VIRGOHI21 hypothesis. And because I'm not insanely belligerent, I caved in and took
    the footnote out. Fortunately I don't have to do that on social media... :)
    VIRGO
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    The Evolution of Massive Galaxy Clusterssu201703 | www.cfa.harvard.edu/
    https://www.cfa.harvard.edu/news/su201703

    CfA astronomer Brian Stalder and a team of colleagues used the SPT survey data to identify twenty-six of the most massive clusters known,
    each with a mass of over about a million billion solar-masses. They find that the clusters are broadly in agreement with the current thinking
    about the evolution of massive clusters and the stars in these galaxies. The models suggest a generally passive evolution (that is, without
    unusual disruptions by collisions or nuclear black hole feedback) and imply that most of the star formation and galaxy merging took place at
    an even earlier epoch than this sample covers. The scientists note, however, that a larger sample is needed to extend the conclusions, and it
    is currently being undertaken using other large optical telescopes including the Magellan twin 6.5 meter telescopes in Chile of which SAO is
    also a leading partner.

    VIRGO
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    Dividing Droplets Could Explain Origin of Life | Quanta Magazine
    https://www.quantamagazine.org/20170119-active-droplets-cell-division/

    A collaboration of physicists and biologists in Germany has found a simple mechanism that might
    have enabled liquid droplets to evolve into living cells in early Earth’s primordial soup.
    VIRGO
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    Did Life Start More Than Once on Earth? - Astrobiology
    http://astrobiology.com/2017/01/did-life-start-more-than-once-on-earth.html

    Conditions suitable to support complex life may have developed in Earth's oceans - and then faded -
    more than a billion years before life truly took hold, a new University of Washington-led study has found.

    The findings, based on using the element selenium as a tool to measure oxygen in the distant past,
    may also benefit the search for signs of life beyond Earth.

    In a paper published Jan. 18 in the Proceedings of the National Academy of Sciences, lead author Michael Kipp,
    a UW doctoral student in Earth and Space Sciences, analyzed isotopic ratios of the element selenium in sedimentary
    rocks to measure the presence of oxygen in Earth's atmosphere between 2 and 2.4 billion years ago.

    VIRGO
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    Eatrh shine na Měsíci je jeden z nejhezčích zážitků na obloze i pro pražáky, ale Pluto shine tak daleko od Slunce je skutečná třešnička!

    This image obtained with the Ralph/Multispectral Visible Imaging Camera aboard NASA’s New Horizons spacecraft shows the night side of Pluto’s
    large, Texas-sized moon Charon, against a star field, lit by faint, reflected light from Pluto itself. The bright crescent on Charon's right
    side is a sliver of sunlit terrain; it is overexposed. New Horizons was already about 100,000 miles (160,000 kilometers) beyond Pluto

    VIRGO
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    https://www.nasa.gov/image-feature/pluto-global-color-map

    This new, detailed global mosaic color map of Pluto is based on a series of three color filter images obtained by the Ralph/
    Multispectral Visual Imaging Camera aboard New Horizons during the NASA spacecraft’s close flyby of Pluto in July 2015.

    VIRGO
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    A Colorful ‘Landing’ on Pluto
    https://www.youtube.com/watch?v=xmqDpuDLVYw
    VIRGO
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    Latest issue of Meteor News online! - Meteor News
    http://meteornews.org/latest-issue-meteor-news-online/

    VIRGO
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    SF State astronomer searches for signs of life on Wolf 1061 exoplanet | SF State News
    http://news.sfsu.edu/news-story/sf-state-astronomer-searches-signs-life-wolf-1061-exoplanet

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

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



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

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

    VIRGO
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    https://www.nasa.gov/...judge-an-asteroid-by-its-cover-mid-infrared-data-from-sofia-shows-ceres-true

    New observations show that Ceres, the largest body in the asteroid belt, does not appear to have the carbon-rich
    surface composition that space- and ground-based telescopes previously indicated.

    Using data primarily from NASA’s Stratospheric Observatory for Infrared Astronomy, SOFIA, a team of astronomers has detected the presence of substantial amounts of
    material on the surface of Ceres that appear to be fragments of other asteroids containing mostly rocky silicates. These observations are contrary to the currently
    accepted surface composition classification of Ceres as a carbon-rich body, suggesting that it is cloaked by material that partially disguises its real makeup.

    “This study resolves a long-time question about whether asteroid surface material accurately reflects the intrinsic composition of the asteroid,” said Pierre Vernazza,
    research scientist in the Laboratoire d’Astrophysique de Marseille (LAM–CNRS/AMU). Our results show that by extending observations to the mid-infrared, the asteroid’s
    underlying composition remains identifiable despite contamination by as much as 20 percent of material from elsewhere,” said Vernazza.

    VIRGO
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    To see finally the face of Peggy - BBC News
    http://www.bbc.com/news/science-environment-38599645

    Scientists studying the splendour of Saturn's rings are hoping soon to get a resolved picture
    of an embedded object they know exists but cannot quite see.

    The moonlet is named after London researcher Carl Murray's mother-in-law, and was first noticed in 2013.
    Its effect on surrounding ice and dust particles has been tracked ever since.

    But no direct image of Peggy's form has yet been obtained, and time is now short.
    The Cassini spacecraft's mission at Saturn is edging to a close and its dramatic end-of-life disposal.

    VIRGO
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    Tunguska Event: Russian Scientists Debunk Meteorite Theory
    https://sputniknews.com/science/201701181049718416-tunguska-event-lake-cheko/

    Lake Cheko was supposed to be the impact crater of the large explosion that occurred near the Tunguska Riva in Russian Siberia,
    which was detected hundreds of miles away. However, Russian scientists revealed that Lake Cheko is at least 280 years old,
    which means that the lake dates back hundreds of years before the Tunguska event.

    The so-called Tunguska event is still a mystery after 108 years. It is the largest impact event on Earth in recorded history.

    VIRGO
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    Včera jsem dořachnul Vesmírné Blues (Paseka), a kolem druhé ráno se uklidil pod peřinu s tím, že si už jen přečtu
    úvod Tegmarka (Argo/Dokořán). V 6:15 jsem s hrůzou zjistil, kolik je hodin, a dnes velmi úspěšně zaspal do práce.
    Zatím je brzy na hodnocení, ale jestli to celé bude takhle "turbo", tak potěš... Na článek jsem teď narazil náhodou,
    ale přesně zapadl do nálady.

    Mapping the multiverse: How far away is your parallel self? | New Scientist
    https://www.newscientist.com/article/mg23331093-100-infinite-frontiers/
    There seems to be an infinity of invisible worlds lurking out there.
    Now we’re starting to get a handle on where they are, and what it might take to reach them

    VIRGO
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    A possible anorthositic continent of early Mars and the role of planetary size for the inception of Earth-like life
    http://www.sciencedirect.com/science/article/pii/S1674987116302158

    VIRGO
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    Help explore Mars by discovering networks of polygonal ridges!
    Zooniverse
    https://www.zooniverse.org/projects/mschwamb/planet-four-ridges
    VIRGO
    VIRGO --- ---
    The $2.4-billion plan to steal a rock from Mars : Nature News & Comment
    http://www.nature.com/news/the-2-4-billion-plan-to-steal-a-rock-from-mars-1.21306
    NASA is now building the rover that it hopes will bring back signs of life on the red planet.

    VIRGO
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    ESOcast 93 Light: Kick-off for Mirrors and Sensors for Biggest Eye on the Sky
    https://www.youtube.com/watch?v=6n5Ctgs6jWA
    VIRGO
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    A Simple Response to an Elemental Message has now spent 100 days in space - not long by International Space
    Station astronauts standards but altogether a small milestone within a much longer journey!

    Traveling at light speed distance for this amount of time will only get you out of our Solar System and near
    the centre of the Oort Cloud, approximately 2,590,206,837,120km / 17,314.46 AU / 0.0839 parsec from The Earth.

    VIRGO
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    Funeral service for Capt. Cernan will be conducted at 14:30 CST / 21:30 CET Jan 24
    St. Martin’s Episcopal Church, 717 Sage Road Houston & aired on NASA TV.

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