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    VIRGOCosmos In Brief - Aktualní novinky vesmírného výzkumu v kostce
    DARKMOOR
    DARKMOOR --- ---
    JULIANNE: JULIANNE: Zkoušel někdo spočítat jak silné by muselo být planetární magnetické pole, aby ochránilo atmosféru planety u neutronové hvězdy?
    VIRGO
    VIRGO --- ---
    http://aasnova.org/2017/08/04/collisions-around-a-black-hole-mean-mealtime/

    When a normally dormant supermassive black hole burps out a brief flare, it’s assumed that a star was torn apart and
    fell into the black hole. But a new study suggests that some of these flares might have a slightly different cause.

    JULIANNE
    JULIANNE --- ---
    DARKMOOR: Ale mně to nevadí, jen mě to překvapilo :). Tomuhle tématu jsem se stejně alespoň protentokrát neměla v úmyslu do hloubky věnovat. A oni alespoň v prvním oddílu článku pracují s daty místo pouze teoretických předpovědí, co je ještě zachytitelné. Já jsem se momentálně zasekla na efektivní teplotě PSR B1257+12. Dostatečně jasnou hodnotu jsem zatím nedohledala, v různých pracích se liší i řádově a obecně teploty neutronových hvězd se liší přes několik řádů. Už se nedivím, že autoři nejnovější práce považují planety v systému za pravděpodobně zmrzlé, zatímco třeba Miller a Hamilton by je odpařili...
    DARKMOOR
    DARKMOOR --- ---
    JULIANNE: Je to jasné, vycucli ti tu myšlenku z hlavy. Pro příště neváhat, psát a publikovat ;)
    JULIANNE
    JULIANNE --- ---
    VIRGO: JULIANNE: Zatím alespoň úvod:

    Feasibility and benefits of pulsar planet characterization

    Abstract
    Planets orbiting neutron stars seem to be rare, but all the more interesting for science due to their origins. Characterizing the composition of pulsar planets could elucidate processes involved in supernova fallback disks, accretion of companion star material, potential survival of planetary cores in the post-MS phase of their stars, and more. However, the small size and unusual spectral distribution of neutron stars make any spectroscopic measurements very difficult if not impossible in the near future. In this work, we set to estimate the feasibility of spectroscopy of planets orbiting specifically pulsars, and to review other possible methods of characterization of the planets, such as emissions from aurorae.

    1. Introduction
    The first ever confirmed extrasolar planets were discovered by Alexander Wolszczan and Dale Frail in 1992 around the stellar remnant PSR B1257+12. The existence of planets around such an extreme stellar object caused much surprise, and yet they have received comparably little attention after discoveries of planets around main sequence (MS) stars, starting with 51 Pegasi b (Mayor & Queloz 1995). Two more pulsar systems have been discovered up to date (Sigurdssson et al. 2003, Bailes et al. 2011), but pulsar planets remain rather understudied. This is understandable due to the apparent scarcity of these systems, the difficulty of learning anything but the mass of the planet(s) through pulsar timing, and the absence of direct relevance for search for Earth-like planets and conditions for life. However, their indirect importance may be high (not speaking of direct relevance for many other fields), and the formation, evolution and characteristics of pulsar planetary systems may prove relevant even for the popular topic of searching for “Earth 2.0”.
    To start with their formation, there are five basic ways how a pulsar may acquire planets: i) they could be remnants of planetary cores of objects formed in-situ, ii) they could be objects formed in-situ from the fallback debris after a supernova explosion, iii) they could be objects formed in-situ from a debris disk from a merger of two white dwarfs, which also gave existence to the pulsar, iv) they could be remnants of a stellar companion that lost most of its mass either to the pulsar, or during the supernova explosion, or v) they could be captured objects, most likely from a companion star, less likely rogue planets. Podsiadlowski (1993) used finer criteria to describe different formation processes, and summarized the following options: planet survival; fallback disk origin; WD-WD/WD-NS merger; disrupted companion forming a disk; planet capture; evaporation of a stellar companion; ablation of a close binary during the supernova explosion; Be binary model (where a massive disk is accreted from a massive companion); massive binary model (where a circumbinary planet is dragged in during the Thorne-Żytkov phase); TŻO deflation (where the TŻO envelope deflates to form a massive disk); protostellar disk capture by a millisecond pulsar; planets surviving around an overmassive WD. We refer the reader to study the possible frequency and predictions of the individual models in the Podsiadlowski (1993) paper.
    Considering the PSR B1257+12 system (Wolszczan & Frail 1992, Wolszczan 1994), Podsiadlowski (1993) concluded that a white dwarf merger is the likeliest scenario. Margalit and Metzger (2016) proposed a formation by tidal disruption of a C/O white dwarf companion by the pulsar, specifying a more general companion disruption scenario (Yan et al., 2013) and providing valuable scenarios of disk evolution for both WD-NS merger disks and supernova fallback disks.
    PSR B1620-26 b is a circumbinary planet orbiting a pulsar and a white dwarf, and likely formed around the white dwarf precursor, with its system later captured by the pulsar, giving rise to a binary, while the pulsar’s original stellar companion was ejected (Sigurdssson et al. 2003). In a globular cluster with high star density, where this system is present, such an event is more likely than in the galactic disk. Finally, the PSR J1719-1438 system contains most likely a remnant of a disrupted WD companion that narrowly avoided its complete destruction, based on its minimum density (Bailes et al. 2011).
    The nearly coplanar orbits of the first three discovered pulsar planets around PSR B1257+12 (REF) suggest formation in-situ. The possibility of an in-situ formation, especially by a WD-WD/NS-WD merger or companion disruption, is further supported by the discovery of a circumstellar disk of the magnetar 4U 0142+61 (Wang et al. 2006), and a tentative asteroid belt around the millisecond pulsar B1937+21 (Shannon et al. 2013). There is also evidence of an asteroid or in-falling debris around PSR J0738−4042, a middle-aged, isolated radio pulsar (Brook et al. 2013).
    But we cannot completely discount the option of planetary cores surviving a supernova explosion, however unlikely it seems, and although it’s not applicable to planets of recycled pulsars. Podsiadlowski (1993) notes that in case of an asymmetric explosion, if the neutron star receives a kick of the order of the orbital velocity of the planet (and in a direction similar to the planet’s motion during the supernova explosion), the stellar remnant may retain the planet, which would otherwise become gravitationally unbound in case of a symmetric explosion. In this scenario, the planets’ composition would likely be heavily altered by the event. Not only would likely only cores of massive and preferably distant planets survive, but the conditions during a supernova explosion, especially the strong neutrino flow, could change the core’s chemical make-up as well, but a detailed model of the compositional changes is out of the scope of this study.
    Planets formed from the supernova fallback material – if possible despite its low angular momentum – would also exhibit likely very distinct properties; we could expect metal-rich composition and a variety of short-lived isotopes. Planets arising from WD disruption disks can be expected to have a predominantly carbonaceous composition – essentially to be “diamond planets” (Margalit & Metzger 2016, Kuchner & Seager 2005). On the other hand, planets captured after the explosion would not possess the above-described distinct properties. Finally, planets arising directly from WDs would be recognizable by their extreme density.
    Recently, another formation possibility has been mentioned by Greaves & Holland (2017), based on observation of the Geminga pulsar’s interaction with the interstellar medium (ISM). ISM dust grains seemed to be able to penetrate into the pulsar wind nebula. With enough infalling dust, a disk around the pulsar might form. While ISM in general is composed mainly of hydrogen and helium, the dust particles contain a lot of oxygen, iron, magnesium and other heavier elements (Pinto et al. 2013), so it is conceivable that such a disk would provide a planetary-forming environment. These planets would likely manifest properties akin to those orbiting MS stars.
    Could pulsar planets possess atmospheres? The answer to that question depends on the star-planet distance and the formation mechanism. Detailed models that are out of the scope of this paper are needed to answer it more reliably; what follows in the rest of the paragraph remains pure speculation insofar. We expect that captured planets could hold onto their atmospheres, if their orbital separation is sufficiently large. The chance of atmospheres on cores surviving the supernova explosion or formed around the pulsar seems low, even if there is sufficient fallback material. Planets originating from a companion disruption disk might be able to form an atmosphere, most likely CO-dominated (Kuchner and Seager, 2006). But since most of pulsars’ spin-down energy is released in the form of relativistic particles – pulsar wind –, any atmosphere might be quickly eroded unless the planet also possessed a magnetic field. This particular case would increase the chances of characterization.
    Patruno and Kama (2017) have recently investigated the survival of pulsar planets’ atmospheres and the potential habitability of these worlds. __________________(doplnit)
    Do the great distance of known pulsar systems and the faintness of the light source present insurmountable obstacles for now and the near future, or could they be resolved? We try to provide estimates for expected planetary characteristics and future observation in the next sections of our paper.
    JULIANNE
    JULIANNE --- ---
    VIRGO: Taky pravda. Pak sem nahodím draft, až bude působit jako celistvý text. Doufám, že to stihnu do úterka.
    Pak už na arxiv, nasbírat feedback - a vytvořit poster na EPSC.
    VIRGO
    VIRGO --- ---
    JULIANNE: :-))

    Ostych stranou, tato témata jsou dnes už "na pořadu (každého) dne." :D
    JULIANNE
    JULIANNE --- ---
    Člověk má od dubna rozepsaný draft článku k teoretickým možnostem charakterizace pulsarových planet, říká si, že otázku obyvatelnosti nezmíní, aby už tak poněkud futuristické téma nepůsobilo moc šíleně, a on k tomu mezitím vznikne článek :):
    [1705.07688] Neutron Star Planets: Atmospheric processes and habitability
    https://arxiv.org/abs/1705.07688
    VIRGO
    VIRGO --- ---
    Detecting Exoplanet Life in Our Proximity | astrobites
    https://astrobites.org/2017/08/01/detecting-exoplanet-life-in-our-proximity/

    Detecting Proxima b’s Atmosphere with JWST Targeting CO2 at 15 Micron Using a High-Pass Spectral Filtering Technique.

    Since the discovery of this close planet, researchers have been studying methods that might detect the presence of life on Proxima Centauri b.
    Today’s paper by devising a method to detect CO2 in the planet’s atmosphere. They focus on this particular molecule because it is one of the
    four main biomarkers used in evaluating habitability of exoplanets; water, methane, carbon dioxide, and oxygen are primarily produced during
    biological processes, so their presence in the atmosphere implies life. In addition to being a biomarker molecule, carbon dioxide (CO2) has
    many distinguishable features that are visible on the 15 micron band, which JWST is equipped to look at.

    These researchers present a technique that can be performed with the soon-to-be-launched James Webb Space Telescope (JWST) which will reveal
    the presence of CO2 in the atmosphere of this nearby exoplanet. The emission in the 15 micron band will be ideal for detecting CO2, since
    this molecule has over 100 features within this band.

    VIRGO
    VIRGO --- ---
    Pořád probíhá vyhodnocování výsledků posledního pozorování zákrytu. Podle posledních výsledků je 2014 MU69 výrazně nesferický,
    možná dokonce kontaktní binární objekt, v extrémním případě může jít dokonce o dvojici objektů. Odhadovaná podélná velikost v případě
    jednoho asymetrického tělesa je zhruba 30 km, v případě dvojice (ať už kontaktní či těsně obíhající) 15 - 20 km pro každý objekt.

    https://www.nasa.gov/feature/new-horizons-next-target-just-got-a-lot-more-interesting

    VIRGO
    VIRGO --- ---
    VIRGO
    VIRGO --- ---
    No a report měsíce - tým DES (Dark Energy Survey) dnes oficiálně publikoval výsledky ročního výzkumu vesmíru na velkých škálách
    (i když tento program probíhá už 4 roky), pomocí 4m teleskopu observatoře Cerro Tololo na speciálně vytvořené 570 Mpx kameře DECam,
    vyvinuté ve Fermilabu. Její citlivost umožňuje zachytit světlo galaxií vzdálených 8 mld svět. let od nás (což odpovídá zhruba 1/3
    staří současného vesmíru).

    Snímkováno a zaneseno do mapy bylo na 26 000 000 galaxií, jedním z hlavních cílů programu bylo podrobné pozorování temné hmoty a energie,
    které tvoří 96 % obsahu pozorovaného vesmíru. Studie potvrdila sočasný konsenzus rozložení: viditelná 4%, TH 26%, TE 70% (zaokrouhleno).

    Výsledkem je dosud nejpodrobnější mapa navelkých škálách, co víc výsledky jsou v dobré shodě s měřením detektorem PLANCK.

    http://news.fnal.gov/...k-energy-survey-reveals-accurate-measurement-dark-matter-structure-universe/



    Hlavní rozcestník/seznam článků, které budou cca do týdne publikovány na arXivu:
    https://www.darkenergysurvey.org/des-year-1-cosmology-results-papers/

    Živé záznamy: http://vms.fnal.gov/asset/livevideo

    SLAC and Stanford astrophysicists made crucial contributions to the galaxy survey,
    showing that the universe clumps and expands as predicted by our best cosmological models.

    https://www6.slac.stanford.edu/...odel-universe-withstands-most-precise-test-dark-energy-survey.aspx

    https://www.youtube.com/watch?v=kts4PxFwUSo

    Dark Energy Survey Year 1 Results: Galaxy-Galaxy Lensing
    http://www.darkenergysurvey.org/wp-content/uploads/2017/08/y1ggl.pdf



    The paper describing the redshift distributions for the 26 million weak lensing source galaxies.
    http://www.darkenergysurvey.org/wp-content/uploads/2017/08/y1kpdndz.pdf



    Dark energy is so weak you'd need a cube of it 160km across to boil a kettle - @joezuntz

    VIRGO
    VIRGO --- ---
    Strict rules around contamination hamper exploration for life | Cosmos
    https://cosmosmagazine.com/...ct-rules-around-contamination-hamper-exploration-for-life-beyond-earth

    Is our search for alien life being held back by our desire to protect it?

    NASA’s orbiter Cassini will make a series of decreasing orbits that will end in a fiery death dive into Saturn’s atmosphere in
    September. This deliberate termination of a still serviceable spacecraft is to comply with “planetary protection” protocols,
    designed to minimise the risk of depositing stowaway Earth microbes into an environment where they might be able to reproduce.

    The particular fear in this case is that if Cassini were allowed to become derelict in orbit it might eventually crash into Enceladus –
    a moon of Saturn now realised to have a watery interior that is eminently habitable for microbes. By similar reasoning, NASA’s first
    Jupiter orbiter Galileo was made to burn up in the planet’s atmosphere in 2003 rather than risk a future crash into its microbially
    habitable moon Europa. The same fate awaits Juno in February 2018.
    VIRGO
    VIRGO --- ---
    Our Solar System’s “shocking” origin | Carnegie Institution for Science
    https://carnegiescience.edu/news/our-solar-system%E2%80%99s-%E2%80%9Cshocking%E2%80%9D-origin

    According to one longstanding theory, our Solar System's formation was triggered by a shock wave from an exploding supernova. The shock wave injected material
    from the exploding star into a neighboring cloud of dust and gas, causing it to collapse in on itself and form the Sun and its surrounding planets.

    New work from Carnegie's Alan Boss offers fresh evidence supporting this theory, modeling the Solar System's formation beyond the initial cloud collapse and
    into the intermediate stages of star formation. It is published by the Astrophysical Journal.

    VIRGO
    VIRGO --- ---
    Reflections from an Alien World | Tiffany Jansen
    https://www.youtube.com/watch?v=_A9CfEEXMqQ
    VIRGO
    VIRGO --- ---
    VIRGO
    VIRGO --- ---
    New Space Simulations Show What Happens When Neutron Star, Black Hole Collide | Berkeley Lab
    http://newscenter.lbl.gov/2017/08/02/new-space-simulations-neutron-star-black-hole-mergers/

    Berkeley Lab scientists develop detailed models that provide new views of cataclysmic events in space

    Now that scientists can detect the wiggly distortions in space-time created by the merger of massive black holes,
    they are setting their sights on the dynamics and aftermath of other cosmic duos that unify in catastrophic collisions.

    Working with an international team, scientists at the Department of Energy’s Lawrence Berkeley National Laboratory
    (Berkeley Lab) have developed new computer models to explore what happens when a black hole joins with a neutron star –
    the superdense remnant of an exploded star.

    VIRGO
    VIRGO --- ---
    NRL Brightens Perspective of Mysterious Mini-Halos - U.S. Naval Research Laboratory
    https://www.nrl.navy.mil/...ia/news-releases/2017/NRL-Brightens-Perspective-of-Mysterious-Mini-Halos

    The largest gravitationally bound objects in the universe are galaxy clusters that form at the intersection of cosmic web filaments.
    These entities are shaped and grow through massive collisions as material streams into their gravitational pull. Within the heart
    of some galaxy clusters are mysterious and little known radio mini-halos. These rare, dispersed, and steep-spectrum (brighter at
    low frequencies) radio sources surround a bright central radio galaxy and are highly luminous at radio wavelengths.

    XCHAOS
    XCHAOS --- ---
    :: OSEL.CZ :: - Způsobují rádiové záblesky hvězdy z temné hmoty padající do černých děr?
    http://www.osel.cz/...9-zpusobuji-radiove-zablesky-hvezdy-z-temne-hmoty-padajici-do-cernych-der.html
    Fast radio bursts may be dark matter ‘stars’ hitting black holes | New Scientist
    https://www.newscientist.com/...2527-fast-radio-bursts-may-be-dark-matter-stars-hitting-black-holes/
    VIRGO
    VIRGO --- ---
    What Would It Take To Completely Sterilize the Earth? - The Atlantic
    https://www.theatlantic.com/.../2017/07/what-would-it-take-to-completely-sterilize-the-earth/533613/

    Three astrophysicists calculate that even huge asteroids and exploding stars probably wouldn’t wipe out all life.

    The odds of finding life on another planet hinge on the answers to two big questions. First, how often does life arise? Second, once it does arise,
    how likely is it to persist without being completely wiped out? The first question is extremely difficult, especially since we have exactly one example
    of a life-spawning planet. But the second question is easier to answer—at least for Earth—and a trio of astrophysicists have given it a shot.

    In a paper delightfully titled “The Resilience of Life to Astrophysical Events,” David Sloan and Rafael Alves Batista, both from the University of Oxford,
    and Avi Loeb, from Harvard University, estimated the odds that a space-borne catastrophe like an incoming asteroid would completely sterilize the Earth.
    Reassuringly, they think those odds are astronomically low—about one in 10 million for every billion years. “The conclusion we come to is that life, once it
    starts anywhere, is hard to eradicate,” Sloan says. In other words: Life finds a way (even if you bludgeon it with a giant space rock or an exploding star).

    To be clear, the three researchers aren’t concerned with the fate of humans—a fragile, fleshy species that, in Loeb’s words, can be “killed by climate change
    or affected by bad politics.” Instead, the trio wanted to know what it would take to wipe out all life on the planet. And to do that, they focused on the world’s
    hardiest animals—the tardigrades.

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