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  • richardmitnick 12:33 pm on April 26, 2016 Permalink | Reply
    Tags: , , space.com, Wolf-Rayet stars   

    From SPACE.com: “Wolf-Rayet Stars: Sounds Like Sci-Fi, But Full of Sci-Fact” 

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    SPACE.com

    April 25, 2016
    Paul Sutter, Astrophysicist
    The Ohio State University, chief scientist at COSI Science Center

    1
    A giant bubble blown by the massive Wolf-Rayet star HD 50896, the pink star in the centre of the image.
    Credit: ESA, J. Toala & M. Guerrero (IAA-CSIC), Y.-H. Chu & R. Gruendl (UIUC), S. Arthur (CRyA–UNAM), R. Smith (NOAO/CTIO), S. Snowden (NASA/GSFC) and G. Ramos-Larios (IAM)

    Sometimes I get a little jealous of pre-20th century astronomers. Nowadays, if you discover something new you get to name it. Back then, if you discovered something new, it got named after you.

    Such was the case when Charles Wolf and Georges Rayet happened upon a strange star one night at the Paris Observatory in 1867. I don’t know what they said to each other after the discovery — even if I could overhear them, my French is a little too rusty — but it probably wasn’t, “Sweet! Our names get to be featured in a skipped-over chapter of every astronomy textbook of the future!”

    You just have that glow

    What cemented their place in trivia lore was the peculiar properties of the light coming from that star they observed. Until then, nobody had seen anything quite like it. And by “it,” I mean emission spectral lines.

    OK, I admit it, that sentence probably doesn’t sound very impressive. Let’s dig ourselves out of the jargon. If you have something hot — a light bulb, say, or maybe a star — it will glow. The light it gives off is a mixture of all sorts of wavelengths. If it’s the right temperature, the wavelengths will be an even mixture of reds, greens and blues, which our brains correctly interpret as “white.” If the object is a little hotter, its light might be a mixture of ultraviolets and blues, without any of the cooler red wavelengths. Once again, our brains identify its color, this time as a “blue” thing.

    You, too, are glowing, and not in the way people like to compliment each other. All the atoms and molecules on the surface of your body are a hoppin’, and a jigglin’, and a dancin’. They give off all sorts of wavelengths of light, but mostly in the infrared part of the spectrum. Slap on some infrared goggles, and people light up like a candle.

    Stars are made of stuff that’s wiggling about like crazy, too, and sure enough, they glow. So when we look in detail at the mixture of light coming from a star, we see all sorts of wavelengths.

    Usually, though, there are some wavelengths missing. This is because the outer layers of a star’s atmosphere have a bunch of atomic junk in them, and those atoms can filter out very specific wavelengths of light. They do this by sucking up those light photons, allowing them to jump to a higher quantum mechanical state, and giving off the energy some other way, usually through vibrations.

    But when Wolf and Rayet looked through their télescope, they instead found extra light at specific wavelengths, not subtracted light. Mon dieu!

    Unsolved mysteries

    It took a while to figure out what was going on, and to be perfectly honest, astronomers still aren’t exactly sure what’s causing it.

    One of the problems is that Wolf-Rayet stars are rare. Just a paltry few hundred in our Milky Way, compared to the hundreds of billions of every other kind of star. So we don’t exactly have a lot of data to go on.

    Wolf-Rayet stars are so rare because they’re massive, meaning a) there’s just fewer of them to start with, because it’s hard to get big balls of gas in the first place, and b) massive stars don’t live long, so if we take a snapshot of the universe, we’re more likely to see the smaller, long-lived stellar denizens than their big-boned cousins.

    That massiveness is a clue to their peculiar light pattern. They appear to be a normal stage in the evolution of a giant star, after the initial hydrogen burn run in the core, and just before the inevitable fireworks show of a supernova — they’re waiting in the galactic green room, just about to burst onto the stage in a grand finale performance.

    And in that warm-up phase, the star throws some serious temper tantrums. Entire layers of the star will peel off like a plasma onion, violently thrown into the surrounding system. The inner regions of the star, naked and exposed to the vacuum of space for the first time, glow much more brightly and intensely than those outer layers. Spewing high-energy radiation, that blinding light impacts the thrown-off gas cloud.

    The ejected gas absorbs high-energy ultraviolet radiation, and spits it back out as lower-energy, safe-for-kids infrared and visible light, creating extra light at very specific wavelengths. At last: emission spectral lines.

    This process is called fluorescence, and you might be more familiar with it in other settings. What do CFL bulbs, deep-sea jellyfish and Wolf-Rayet stars have in common?

    Fluorescence. They have fluorescence in common.

    Honestly, all of this is a guess. A good guess, but a guess nonetheless. Like I said, there aren’t a lot of examples to observe, but we’re making do with what we’ve got.

    Since Wolf-Rayet stars appear to be a warm-up act to a big supernova, by studying them in more detail we can better understand the conditions, warning signs, and circumstances of the Big Blasts themselves. Every little bit helps (with thanks to old-timey French astronomers).

    See the full article here .

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  • richardmitnick 9:51 am on April 21, 2016 Permalink | Reply
    Tags: , , , space.com   

    From SPACE.com: “What Are Cosmic Rays?” 

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    SPACE.com

    April 21, 2016
    Elizabeth Howell

    1
    Showers of high energy particles occur when energetic cosmic rays strike the top of the Earth’s atmosphere. Most cosmic rays are atomic nuclei: most are hydrogen nuclei, some are helium nuclei, and the rest heavier elements. Although many of the low energy cosmic rays come from our Sun, the origins of the highest energy cosmic rays remains unknown and a topic of much research. This drawing illustrates air showers from very high energy cosmic rays. Credit: Simon Swordy (U. Chicago), NASA

    Cosmic rays are atom fragments that rain down on the Earth from outside of the solar system. They blaze at the speed of light and have been blamed for electronics problems in satellites and other machinery.

    First discovered in 1912, many things about cosmic rays remain a mystery more than a century later. One prime example is exactly where they are coming from. Most scientists suspect their origins are related to supernovas (star explosions), but the challenge is that cosmic ray origins appear uniform when you look across the entire sky.

    History

    While cosmic rays were only discovered in the 1900s, scientists knew something mysterious was going on as early as the 1780s. That’s when French physicist Charles-Augustin de Coulomb — best known for having a unit of electrical charge named after him — observed an electrically charged sphere suddenly and mysteriously not being charged any more.

    At the time, air was thought to be an insulator and not an electric conductor. With more work, however, scientists discovered that air can conduct electricity if its molecules are charged or ionized. This would most commonly happen when the molecules interact with charged particles or X-rays.

    What Are Cosmic Rays?

    Showers of high energy particles occur when energetic cosmic rays strike the top of the Earth’s atmosphere. Most cosmic rays are atomic nuclei: most are hydrogen nuclei, some are helium nuclei, and the rest heavier elements. Although many of the low energy cosmic rays come from our Sun, the origins of the highest energy cosmic rays remains unknown and a topic of much research. This drawing illustrates air showers from very high energy cosmic rays.
    Credit: Simon Swordy (U. Chicago), NASA

    Cosmic rays are atom fragments that rain down on the Earth from outside of the solar system. They blaze at the speed of light and have been blamed for electronics problems in satellites and other machinery.

    First discovered in 1912, many things about cosmic rays remain a mystery more than a century later. One prime example is exactly where they are coming from. Most scientists suspect their origins are related to supernovas (star explosions), but the challenge is that cosmic ray origins appear uniform when you look across the entire sky.

    History

    While cosmic rays were only discovered in the 1900s, scientists knew something mysterious was going on as early as the 1780s. That’s when French physicist Charles-Augustin de Coulomb — best known for having a unit of electrical charge named after him — observed an electrically charged sphere suddenly and mysteriously not being charged any more.

    At the time, air was thought to be an insulator and not an electric conductor. With more work, however, scientists discovered that air can conduct electricity if its molecules are charged or ionized. This would most commonly happen when the molecules interact with charged particles or X-rays.

    But where these charged particles came from was a mystery; even attempts to block the charge with large amounts of lead were coming up empty. On Aug. 7, 1912, physicist Victor Hess flew a high-altitude balloon to 17,400 feet (5,300 meters). He discovered three times more ionizing radiation there than on the ground, which meant the radiation had to be coming from outer space.

    But tracing cosmic ray “origin stories” took more than a century. In 2013, NASA’s Fermi Gamma-ray Space Telescope released results from observing two supernova remnants in the Milky Way: IC 433 and W44.

    NASA/Fermi Telescope
    NASA/Fermi Telescope

    2
    An artist’s illustration of a supernova explosion, which sends off shock waves that accelerate protons to the point that they become cosmic rays, a process called Fermi acceleration. Many details of Fermi acceleration are unknown, but data from NASA’s Fermi Gamma-ray Space Telescope provide overwhelming evidence that Fermi acceleration is responsible for cosmic rays. Image released Feb. 14, 2013.
    Credit: Greg Stewart/SLAC National Accelerator Laboratory

    Among the products of these star explosions are gamma-ray photons, which (unlike cosmic rays) are not affected by magnetic fields. The gamma rays studied had the same energy signature as subatomic particles called neutral pions. Pions are produced when protons get stuck in a magnetic field inside the shockwave of the supernova and crash into each other.

    In other words, the matching energy signatures showed that protons could move at fast enough speeds within supernovas to create cosmic rays.

    Current science

    We know today that galactic cosmic rays are atom fragments such as protons (positively charged particles), electrons (negatively charged particles) and atomic nuclei. While we know now they can be created in supernovas, there may be other sources available for cosmic ray creation. It also isn’t clear exactly how supernovas are able to make these cosmic rays so fast.

    Cosmic rays constantly rain down on Earth, and while the high-energy “primary” rays collide with atoms in the Earth’s upper atmosphere and rarely make it through to the ground, “secondary” particles are ejected from this collision and do reach us on the ground.

    But by the time these cosmic rays get to Earth, it’s impossible to trace where they came from. That’s because their path has been changed as they travelled through multiple magnetic fields (the galaxy’s, the solar system’s and Earth’s itself.)

    According to NASA, cosmic rays therefore come equally from all directions of the sky. So scientists are trying to trace back cosmic ray origins by looking at what the cosmic rays are made of. Scientists can figure this out by looking at the spectroscopic “signature” each nucleus gives off in radiation, and also by weighing the different isotopes (types) of elements that hit cosmic ray detectors.

    The result, NASA adds, shows very common elements in the universe. Roughly 90 percent of cosmic ray nuclei are hydrogen (protons) and 9 percent are helium (alpha particles). Hydrogen and helium are the most abundant elements in the universe and the origin point for stars, galaxies and other large structures. The remaining 1 percent are all elements, and it’s from that 1 percent that scientists can best search for rare elements to make comparisons between different types of cosmic rays.

    Scientists can also date the cosmic rays by looking at radioactive nuclei that decrease over time. Measuring the “half life” of each nuclei gives an estimate of how long the cosmic ray has been out there in space.

    Space radiation concerns

    Earth’s magnetic field and atmosphere shields the planet from 99.9 percent of the radiation from space. However, for people outside the protection of Earth’s magnetic field, space radiation becomes a serious hazard. An instrument aboard the Curiosity Mars rover during its 253-day cruise to Mars revealed that the radiation dose received by an astronaut on even the shortest Earth-Mars round trip would be about 0.66 sievert. This amount is like receiving a whole-body CT scan every five or six days.

    A dose of 1 sievert is associated with a 5.5 percent increase in the risk of fatal cancers. The normal daily radiation dose received by the average person living on Earth is 10 microsieverts (0.00001 sievert).

    The moon has no atmosphere and a very weak magnetic field. Astronauts living there would have to provide their own protection, for example by burying their habitat underground.

    The planet Mars has no global magnetic field. Particles from the sun have stripped away most of Mars’ atmosphere, resulting in very poor protection against radiation at the surface. The highest air pressure on Mars is equal to that at an altitude of 22 miles (35 kilometers) above the Earth’s surface. At low altitudes, Mars’ atmosphere provides slightly better protection from space radiation.

    See the full article here .

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  • richardmitnick 2:56 pm on March 29, 2016 Permalink | Reply
    Tags: , , , Life's Building Blocks Form In Replicated Deep Sea Vents, , space.com   

    From SPACE.com: “Life’s Building Blocks Form In Replicated Deep Sea Vents” 

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    SPACE.com

    March 28, 2016
    Charles Q. Choi

    1
    Alkaline hydrothermal vents may have played a role in the origin of life.
    Credit: NOAA

    Chimney-like mineral structures on the seafloor could have helped create the RNA molecules that gave rise to life on Earth and hold promise to the emergence of life on distant planets.

    Scientists think Earth was born roughly 4.54 billion years ago. Life on Earth may be nearly that old with recent findings suggesting that life might have emerged only about 440 million years after the planet formed.

    However, it remains a mystery how life might have first arisen. The main building blocks of life now are DNA, which can store genetic data, and proteins, which include enzymes that can direct chemical reactions. However, DNA requires proteins in order to form, and proteins need DNA to form, raising the chicken-and-egg question of how protein and DNA could have formed without each other.

    To resolve this conundrum, scientists have suggested that life may have first primarily depended on compounds known as RNA. These molecules can store genetic data like DNA, serve as enzymes like proteins, and help create both DNA and proteins. Later DNA and proteins replaced this “RNA world” because they are more efficient at their respective functions, although RNA still exists and serves vital roles in biology.

    However, it remains uncertain how RNA might have arisen from simpler precursors in the primordial soup that existed on Earth before life originated. Like DNA, RNA is complex and made of helix-shaped chains of smaller molecules known as nucleotides.

    One way that RNA might have first formed is with the help of minerals, such as metal hydrides. These minerals can serve as catalysts, helping create small organic compounds from inorganic building blocks. Such minerals are found at alkaline hydrothermal vents on the seafloor.

    Alkaline hydrothermal vents are also home to large chimney-like structures rich in iron and sulfur. Prior studies suggested that ancient counterparts of these chimneys might have isolated and concentrated organic molecules together, spurring the origin of life on Earth.

    To see how well these chimneys support the formation of strings of RNA, researchers synthesized chimneys by slowly injecting solutions containing iron, sulfur and silicon into glass jars. Depending on the concentrations of the different chemicals used to grow these structures, the chimneys were either mounds with single hollow centers or, more often, spires and “chemical gardens” with multiple hollow tubes.

    2
    Chimney-like mineral structures created in the lab created from solutions containing iron, sulfur and silicon under a) low concentrations and b) high concentrations. Structures in a) represent mound (left) and spindle (right) formations, while those in b) represent chemical garden formations.
    Credit: Bradley Burcar et al., Astrobiology.

    “Being able to perform our experiments in chimney structures that looked like something one might encounter in the darker regions of Tolkien’s Middle Earth gave these studies a geologic context that sparked the imagination,” said study co-author Linda McGown, an analytical chemist and astrobiologist at Rensselaer Polytechnic Institute in Troy, N.Y.

    The chimneys were grown in liquids and gases resembling the oceans and atmosphere of early Earth. The liquids were acidic and enriched with iron, while the gases were rich in nitrogen and had no oxygen. The scientists then poked syringes up the chimneys to pump alkaline solutions containing a variety of chemicals into the model oceans. This simulated ancient vent fluid seeping into primordial seas.

    Sometimes the researchers added montmorillonite clay to their glass jars. Clays are produced by interactions between water and rock, and would likely have been common on the early Earth, McGown said.

    The kind of nucleotides making up RNA are known as ribonucleotides, since they are made with the sugar ribose. The scientists found that unmodified ribonuclotides could form strings of two nucleotides. In addition, ribonucleotides “activated” with a compound known as imidazole — a molecule created during chemical reactions that synthesize nucleotides — could form RNA strings or polymers up to four ribonucleotides long.

    “In order to observe significant RNA polymerization on the time scale of laboratory experiments, it is generally necessary to activate the nucleotides,” McGown said. “Imidazole is commonly used for nucleotide activation in these types of experiments.”

    The scientists found that not only was the chemical composition of the chimneys important when it came to forming RNA, but the physical structure of the chimneys was key too. When the researchers mixed iron, sulfur and silicon solutions into their simulated oceans, instead of slowly injecting them into the seawater to form chimneys, the resulting blend could not trigger RNA formation.

    “The chimneys, and not just their constituents, are responsible for the polymerization,” McGown said.

    These experiments for the first time demonstrate that RNAs can form in alkaline hydrothermal chimneys, albeit synthetic ones.

    “Our goal from the start of our RNA polymerization research has been to place the RNA polymerization experiments as closely as possible in the context of the most likely early Earth environments,” McGown said. “Most previous RNA polymerization research has focused on surface environments, and the exploration of deep-ocean hydrothermal vents could yield exciting new possibilities for the emergence of an RNA world.”

    One concern about these findings is that the experiments were performed at room temperature. Hydrothermal vents are much hotter, and such temperatures could destroy RNA. [Video: The Search For Another Earth]

    “Keep in mind, however, that hydrothermal vents are dynamic systems with gradients of chemical and physical conditions, including temperature,” McGown said.

    In principle, cooler sections of hydrothermal vents might have nurtured RNA and its precursor molecules, she said.

    In the future, McGown and her colleagues will perform experiments investigating what effects variables such as pressure, temperature and mineralogy might have on the formation of RNA molecules, focusing primarily on conditions mimicking deep-ocean environments on an early Earth and those that may also have existed on Mars and elsewhere, McGown said.

    The scientists detailed their findings in the July 22 issue of the journal Astrobiology.

    Science team:

    Bradley T. Burcar,1,2 Laura M. Barge,3,4 Dustin Trail,1,5,* E. Bruce Watson,1,5 Michael J. Russell,3,4 and Linda B. McGown1,2
    1 New York Center for Astrobiology, Rensselaer Polytechnic Institute, Troy, New York.
    2 Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York.
    3 NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California.
    4 NASA Astrobiology Institute, Icy Worlds.
    5 Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute School of Science, Troy, New York.

    See the full article here .

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  • richardmitnick 5:32 am on March 18, 2016 Permalink | Reply
    Tags: , , , space.com   

    From SPACE.com: “New Dark Matter Theory Weighs Superheavy Particle” 

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    SPACE.com

    March 17, 2016
    Charles Q. Choi

    Dark matter could be made of particles that each weigh almost as much as a human cell and are nearly dense enough to become miniature black holes, new research suggests.

    Dark matter halo  Image credit: Virgo consortium / A. Amblard / ESA
    Dark matter halo Image credit: Virgo consortium

    While dark matter is thought to make up five-sixths of all matter in the universe, scientists don’t know what this strange stuff is made of. True to its name, dark matter is invisible — it does not emit, reflect or even block light. As a result, dark matter can currently be studied only through its gravitational effects on normal matter. The nature of dark matter is currently one of the greatest mysteries in science.

    If dark matter is made of such superheavy particles, astronomers could detect evidence of them in the afterglow of the Big Bang, the authors of a new research study said.

    Previous dark matter research has mostly ruled out all known ordinary materials as candidates for what makes up this mysterious stuff. Gravitational effects attributed to dark matter include the orbital motions of galaxies: The combined mass of the visible matter in a galaxy, such as stars and gas clouds, cannot account for a galaxy’s motion, so an additional, invisible mass must be present. The consensus so far among scientists is that this missing mass is made up of a new species of particles that interact only very weakly with ordinary matter. These new particles would exist outside the Standard Model of particle physics, which is the best current description of the subatomic world.

    Standard model with Higgs New
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Some dark matter models suggest that this cosmic substance is made of weakly interacting massive particles, or WIMPs, that are thought to be about 100 times the mass of a proton, said study co-author McCullen Sandora, a cosmologist at the University of Southern Denmark. However, despite many searches, researchers have not conclusively detected any WIMPs so far, leaving open the possibility that dark matter particles could be made of something significantly different.

    Now Sandora and his colleagues are exploring the upper mass limit of dark matter — that is, they’re trying to discover just how massive these individual particles could possibly be, based on what scientists know about them. In this new model, known as Planckian interacting dark matter, each of the weakly interacting particles weighs about 1^19 or 10 billion billion times more than a proton, or “about as heavy as a particle can be before it becomes a miniature black hole,” Sandora told Space.com.

    A particle that is 1019 the mass of a proton weighs about 1 microgram. In comparison, research suggests that a typical human cell weighs about 3.5 micrograms.

    The genesis of the idea for these supermassive particles “began with a feeling of despondency that the ongoing efforts to produce or detect WIMPs don’t seem to be yielding any promising clues,” Sandora said. “We can’t rule out the WIMP scenario yet, but with each passing year, it’s getting more and more suspect that we haven’t been able to achieve this yet. In fact, so far there have been no definitive hints that there is any new physics beyond the Standard Model at any accessible energy scales, so we were driven to think of the ultimate limit to this scenario.”

    At first, Sandora and his colleagues regarded their idea as little more than a curiosity, since the hypothetical particle’s massive nature meant that there was no way any particle collider on Earth could produce it and prove (or refute) its existence.

    But now the researchers have suggested that if these particles exist, signs of their existence might be detectable in the cosmic microwave background radiation, the afterglow of the Big Bang that created the universe about 13.8 billion years ago.

    Cosmic Microwave Background per Planck
    Cosmic Microwave Background per Planck

    ESA Planck
    ESA/Planck

    Currently, the prevailing view in cosmology is that moments after the Big Bang, the universe grew gigantically in size. This enormous growth spurt, called inflation, would have smoothed out the cosmos, explaining why it now looks mostly similar in every direction.

    After inflation ended, research suggests that the leftover energy heated the newborn universe during an epoch called “reheating.” Sandora and his colleagues suggest that extreme temperatures generated during reheating could have produced large amounts of their superheavy particles, enough to explain dark matter’s current gravitational effects on the universe.

    However, for this model to work, the heat during reheating would have had to be significantly higher than what is typically assumed in universal models. A hotter reheating would in turn leave a signature in the cosmic microwave background radiation that the next generation of cosmic microwave background experiments could detect. “All this will happen within the next few years hopefully, next decade, max,” Sandora said.

    If dark matter is made of these superheavy particles, such a discovery would not only shed light on the nature of most of the universe’s matter, but also yield insights into the nature of inflation and how it started and stopped — all of which remains highly uncertain, the researchers said.

    For example, if dark matter is made of these superheavy particles, that reveals “that inflation happened at a very high energy, which in turn means that it was able to produce not just fluctuations in the temperature of the early universe, but also in [spacetime] itself, in the form of gravitational waves,” Sandora said.

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

    “Second, it tells us that the energy of inflation had to decay into matter extremely rapidly, because if it had taken too long, the universe would have cooled to the point where it would not have been able to produce any Planckian interacting dark matter particles at all.”

    Sandora and his colleagues detailed their findings online March 10 in the journal Physical Review Letters.

    See the full article here .

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    • Ellie Maloney 6:06 am on March 18, 2016 Permalink | Reply

      I actually came up with an idea that dark matter is undetectable because it’s not here. It’s in the ‘yoke’ fold of the universe, that is why it interacts only through gravity. So many years if lab tests did not detect WIMPs so… Maybe we should seriously consider this possibility.

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    • Ellie Maloney 6:16 am on March 18, 2016 Permalink | Reply

      I thought I just posted a comment.. Anyway I was talking about an alternative look at dark matter. What if it is undetectable because it is not here? We have not found WIMPs in years of research. So maybe we should consider a possibility that gravitational effects of DM are detected here, while the matter itself is in a closely folded ‘yoke’ part of the universe. It’s just my speculations of course. But I call it a Wrinkly Egg Universe Theory. https://elliemaloney.wordpress.com/2016/02/25/wrinkly-egg-universe-theory-or-the-theory-of-almost-everything

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    • richardmitnick 3:12 pm on March 18, 2016 Permalink | Reply

      Your comment posted just fine. Thanks for reading and commenting. I think the jury is still out on this one. Maybe this heavy particle will be the one.

      Like

  • richardmitnick 9:16 am on March 16, 2016 Permalink | Reply
    Tags: , , Fu Orionis pre-main sequence star, , space.com   

    From SPACE.com: “Young Stars May Feast Frantically, Grow Chaotically, New Study Shows” 

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    SPACE.com

    March 15, 2016
    Charles Q. Choi

    Infant stars may release bursts of light when they collide with and devour dense clumps of matter that otherwise might have gone on to form planets, new research suggests.

    The new finding has larger implications for understanding how stars grow and evolve early in their lives — specifically, that stars may grow through chaotic series of violent events, instead of steadily getting larger, as previously thought, the authors of the new work noted.

    Stars coalesce from vast clouds of gas and dust, and planets emerge from whirling disks of leftover matter that surround newborn stars. Young stars that are still feeding on their parent clouds are known as protostars, while the disks of material that give rise to planets are known as protoplanetary disks.

    Previous research often envisioned protostars growing in a simple manner, steadily accumulating or accreting fuel from surrounding clouds. However, protostars are often far dimmer than expected, given their estimated average rates of accretion.

    With the new finding, scientists now have evidence that protostars may evolve in an extremely chaotic way, sporadically accreting dense clumps of gas from their surrounding protoplanetary disks.

    For the new work, astronomers focused on protostars known as FU Orionis objects.

    FU Orionis
    Pre-main sequence star FU Orionis. European Southern Observatory via the Digitized Sky Survey

    These young stars, also known as FUors, are known to experience dramatic spikes in brightness, the researchers said. Previous work suggested that FUors brightened because their accretion rates suddenly increased by a factor of 1,000 or more, and staying that way for decades or longer.

    To learn more about these outbursts, scientists used the [NAOJ] Subaru Telescope, located at the Mauna Kea Observatories in Hawaii, to analyze four of the 11 confirmed FUors, located between 1,500 and 3,500 light-years from the Milky Way.

    The new images of the flaring newborn stars “were surprising and fascinating, and nothing like anything previously observed around young stars,” representatives of the National Institutes of Natural Sciences (NINS) in Japan said in a statement. (NINS is one of the managing institutions of the National Astronomical Observatory of Japan, where some of the paper’s authors are based.)

    The researchers discovered “tails” projecting from the protoplanetary material around the young stars, as well as spikes of gas and dust.

    The researchers created computer simulations that suggested that the protoplanetary disks of newly formed stars could be gravitationally unstable and can fragment, creating dense clumps of gas that can collide with the stars, helping them grow and creating those bright bursts of light.

    “We suggest a previously unrecognized evolutionary stage in the formation of stars and protoplanetary disks,” study lead author Hauyu Baobab Liu, an astronomer at the Academia Sinica Institute of Astronomy and Astrophysics in Taipei, Taiwan, told Space.com.

    This unstable phase of a protostar’s life might last several hundred thousand years, the scientists added.

    “Although more simulations are required to match the simulations to the observed images, these images show that this is a promising explanation for the nature of FU Ori[onis]outbursts,” NINS representatives said in the statement.

    The scientists detailed their findings online Feb. 5 in the journal Science Advances.

    See the full article here .

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  • richardmitnick 6:38 am on February 20, 2016 Permalink | Reply
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    From Space.com: “Here’s How It Felt to Discover Gravitational Waves (Kavli Hangout)” 

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    SPACE.com

    February 19, 2016
    Adam Hadhazy

    Gravitational wave Henze NASA
    Depiction of gravitational waves. NASA Henze

    When Rainer “Rai” Weiss and colleagues first proposed an audacious experiment to detect ripples in [spacetime], called gravitational waves, in the late 1970s, they knew the whole endeavor was a long shot. The waves the researchers sought would pull and stretch their detector by mere billionths of a billionth of a meter — a scarcely believable signal to try to extract from nature.

    Now, four decades later, millions of people worldwide have read about the historic detection of gravitational waves as the result of Weiss and his fellow scientists’ efforts: the Laser Interferometer Gravitational-Wave Observatory (LIGO).

    Caltech Ligo
    MIT/Caltech Advanced aLIGO, Hanford, WA, USA

    The revolutionary gravitational wave findings have thrown open the door to a whole new way of studying the universe’s most extreme events and its most massive objects.

    At the U.S. National Science Foundation’s LIGO announcement in Washington, D.C. last week, Weiss called it “a miracle” that the equations first predicting gravitational waves — which Albert Einstein wrote a century ago — work so well in describing the black hole system LIGO found. “It is just amazing,” he said, adding that he’d “love to be able to see Einstein’s face right now” when the physicist’s name came up in a recent Kavli Foundation roundtable.

    Below is a complete transcript of that roundtable, with Weiss joined by two other LIGO researchers, all members of MIT’s Kavli Institute for Astrophysics and Space Research. Nergis Mavalvala has focused on developing LIGO’s precision instruments (and has become a celebrity scientist in her birthplace of Pakistan since the discovery was announced). Matthew Evans has worked on the modeling and control of large interferometers including LIGO.

    Below, read their far-ranging conversation about the ramifications of LIGO’s discovery and what more is in store in the dawning era of gravitational wave astronomy. The following is an edited transcript of the roundtable discussion. The participants have been provided the opportunity to amend or edit their remarks.

    The Kavli Foundation: What does it feel like to have made this discovery? Rai, because you’re one of LIGO’s creators and someone who has pondered how to detect theses waves since the 1970s, let’s start with you.

    Rai Weiss: You’re not going to like my answer — I feel like a monkey just jumped off my back! But the monkey’s not gone yet, he’s still walking along here on the sidewalk. We’ve got more to do. At least some of the guilty feelings that might have come from having dragged all these people along for decades hunting gravitational waves and maybe ruined their careers isn’t happening. So I am very pleased.

    Matthew Evans: If Rai had dragged us all toward our doom, it certainly would have been his fault. [Laughter] I hope he recognizes that he didn’t.

    Nergis Mavalvala: It’s been a real joyride for decades and this is the pinnacle. It’s been amazing to be involved in the science and technology of this effort regardless, and this discovery just makes it all really worthwhile. I don’t think any of us ever feared we were being dragged to our doom. [Laughter] We were just on this great joyride where we didn’t know where we might end up.

    TKF: This discovery of gravitational waves has been a long time in the making and required a lot of patience. Were you all actually surprised, then, at how quickly the detection was made after Advanced LIGO began operating back in September?

    Mavalvala: Yes.

    Evans: Very pleasantly surprised.

    Weiss: It’s amazing. The signal is bigger than we ever imagined it would be.

    Mavalvala: We had thought the first signal would be some little small thing poking up out of the noise and we’d have to work really hard to understand what it was. But in fact, the signal we got is a very clean and beautiful event. It tells us that the binary black holes were located about 1.5 billion light years away. They whirled around each other at nearly the speed of light before a collision that was so powerful, it converted approximately three times the mass of the Sun into gravitational wave energy — in just a few tenths of a second!

    TKF: Two years ago, the BICEP2 Antarctic telescope project announced evidence for the signature of gravitational waves in light from 380,000 years after the Big Bang.

    BICEP 2
    BICEP 2 interior
    BICEP2

    Gravitational Wave Background
    What BICEP2 saw, which was thought to be evidence of gravitational waves, but which was discredited.

    But that major result came into question in early 2015 when other data suggested cosmic dust is a likelier source of the signature. Do you have any concerns about these LIGO findings?

    Evans: I don’t have any concerns about that. I’ve gone through the instruments from one end to the other and I couldn’t find anything that might have gone wrong. But the LIGO Scientific Collaboration, which is the umbrella organization for all the international institutions and scientists involved in this, is very well aware of the history. So the collaboration as a whole has been extremely careful to make sure this discovery is solid.

    Weiss: The signal is so pretty, many of us worried at the time that it was something done maliciously. Matt and others crucially established that the signal is unlikely to have been generated by a hacker and much more likely by nature.

    Mavalvala: The other possibility was that the instruments were misbehaving, but we’ve gone through a very, very detailed study and eliminated that as a possibility.

    Weiss: There’s one other piece of evidence — LIGO has detected more than one of these gravitational wave signals. That to me is a very important piece of the whole thing. Nature seems to behave as we would have expected, which is that it has produced not only a very powerful gravitational wave source like what we have detected and are talking about now, but also a not-so-powerful one of the same kind.

    Evans: Another thing really important to say in contrast to previously declared discoveries of gravitational waves is that we have multiple detectors running simultaneously which detected the same signal. At each site, we have literally thousands of auxiliary channels and sensors looking for any sort of external disturbance and everything checks out.

    TKF: What do you think are the biggest ramifications of this discovery?

    Weiss: For many of us, this is the signal that we wanted to see from the beginning of this whole quest. We wanted to see gravitation à la Einstein and his theory of general relativity and which cannot be explained by any Newtonian mechanisms. The history of general relativity as a science is actually rather dismal. It was mostly theoretical work for many, many years. Then there was a renaissance in the 1960s when people began to realize that maybe the technology had changed enough that you could start doing experiments to test Einstein’s theories. But then physicists ran into this really horrible problem that all the things that they could test were these infinitesimal effects. The bending of light, for example, is a pipsqueak effect. Or the slowing down of clocks in the gravitational field.

    Now all of sudden with LIGO, we’re dealing with a regime where Einstein’s equations had never been applied before. With these colliding black holes , general relativity gives you the right answer, which is miraculous. That is the reason why this is such a big deal. Einstein never expected this kind of test of his theories to happen this way because the effects we’re looking for are so vanishingly small. I keep telling people I’d love to be able to see Einstein’s face right now!

    Mavalvala: Another thing that’s really remarkable is our ability to observe a binary black hole system with LIGO that we could not have observed with light. We could point the best telescopes, sensitive to more or less any electromagnetic wavelength of light, at this system and probably see nothing. We cannot observe this system with any of the other fundamental forces of nature. It has to be gravity.

    If the signal LIGO had detected had been, say, neutron stars colliding and not black holes, we would have had no complaints, but there’s probably a very good chance you could see neutron star mergers with other, conventional observational tools relying on light. In fact, we believe that certain classes of gamma ray bursts are just that. So what we have here in the findings we’re announcing today is very important, in my opinion, because it’s a completely dark-to-light system.

    Evans: To me, this detection means that the stars are no longer silent. The frequencies of gravitational waves that LIGO is designed to detect are actually in the human audible range. So when we’re working on LIGO, we often take its output and put it on a speaker and just listen to it. For this binary black hole system, it made a distinctive, rising “whoooop!” sound. It’s not that we just look up and see anymore, like we always have — we actually can listen to the universe now. It’s a whole new sense, and humanity did not have this sense until LIGO was built.

    Weiss: We often whistled to demonstrate what we thought these smashing black holes might sound like, and it turns out if you play the piano or a keyboard, you can also make a similar sound. Do you know what a glissando is? It’s when you run your fingers very quickly across the keys. If you started at the bottom of a keyboard and went all the way to the middle C and then hold that note for a little bit — that’s what this black hole signal happened to be.

    TKF: It’s remarkable that the pattern or “sound” of gravitational waves detected by LIGO can reveal intricate details about the waves’ sources. For instance, LIGO’s data indicate that each black hole in this collapsing binary system had a mass of about 30 Suns. Until now, we’ve only known about much smaller black holes or supermassive black holes with masses of millions or billions of Suns. How will LIGO help us understand the origin of these never-before-seen, mid-size black holes?

    Evans: Presumably, the existence of these 30 solar-mass black holes — and now after their collision, a nearly 60-solar mass black hole — will tell us something about what we call Population III stars. These are the earliest stars in the universe and are made almost entirely out of hydrogen. They are very massive and one of the plausible sources we’ve suspected for collapsing into these kinds of black holes.

    Weiss: Another idea is that these black holes are made in places where there is a high density of many millions of stars, for example in globular clusters. You can maybe get stars to stick together there and collect and ultimately make a big black hole. There were papers even before our discovery that were beginning to hint that this is the more likely way to get these objects. Now that our findings are out, you watch — in the next year or two, there are going to be probably hundreds of papers about the origin of the black holes we’re talking about. It’s going to be the wave of the future.

    Evans: The amazing thing at LIGO is that gravitational waves carry a tremendous amount of information about their source. As we get more and more of these detections, we’ll even be able to tell how fast the black holes in these binary systems are spinning and if they are spinning in a way that’s aligned. That data will let us decide whether these black holes came from a globular cluster or as a result of primeval Population III stars.

    Cornell SXS teamTwo merging black holes simulation
    Merging black holes, Cornell

    TKF: Turning our conversation to the LIGO observatories themselves — what technological advances did the black hole binary system discovery hinge on? Nergis, you were very involved in this aspect of the work, so please explain.

    Mavalvala: To build one of these gravitational wave detectors — these laser interferometers — you really only need two ingredients. One, you need mirrors that are very, very still. Then two, you need a way of measuring any very small motions. So the name of the game is having ways to shield mirrors from external, non-gravitational wave forces and having laser lights precise enough that you can probe the tiny motions that are induced by gravitational waves. Once you have those two things, you have yourself a detector.

    The changes that granted us more sensitivity during Advanced LIGO were vibration isolation systems that were better than in the previous generation. In a slightly jargon-y way, we don’t use just passive isolation; we’re also using active vibration isolation. The other thing we had to do was reduce the vibrations of the mirrors due to thermally driven fluctuations. Then finally, we put in a more powerful laser so that our signal-to-noise ratio improved. The list of technologies involved in these improvement is very long, but those are the broad-brush strokes.

    TKF: Matt, part of your work involves figuring out the fundamental limits for LIGO and for future gravitational wave detectors. How much more sensitivity to gravitational waves can we achieve and why do we want to?

    Evans: Putting first things first, we haven’t really gotten the Advanced LIGO detectors working as well as they can be. We will in some time. We think we can get a factor of three times as much sensitivity as we have currently, which could bring ten times as many gravitational wave-producing events into LIGO’s range. So we can expect a lot just from the Advanced LIGO detectors as we improve their function.

    The next step we’re looking at is actually something that Nergis has pioneered, and that’s to use quantum optics in our detectors to reduce the quantum noise of the lights. Nergis talked about having lasers that were very precise and high-powered. But you can actually import techniques from a research field called quantum optics to try to reduce some of the randomness that’s inherent to light. Then, we’re looking farther into the future as to whether or not we can build detectors that are still another ten times more sensitive. That will probably involve a new facility and longer interferometers.

    If you ask why we would want to do that, I think that we’ve just started this business. It looks like we have a lot of great physics and astrophysics we can do with these detectors. If we can make something ten times more sensitive, we’ll be able to detect gravitational wave sources from anywhere in the universe.

    TKF: With an even more advanced LIGO, as well as future gravitational-wave observatories, what other phenomena in the universe will we get to understand in new ways?

    Weiss: There is a whole spectrum of gravitational waves. With LIGO, we’re looking for high-frequency waves. As to how high we can go, again, the piano analogy is a wonderful one. Because what we’re looking for are sources that go from the bottom of the piano to the top of the piano. They don’t stop at middle C, which is currently our detection limit with LIGO. They go higher.

    Beyond that, a lot of people are working in other frequencies and other wavelengths where there are phenomena which LIGO will not see. For example, we talked earlier about the BICEP project, which is looking for signatures of gravitational waves affecting the relic radiation from the Big Bang, called the cosmic microwave background. Well, that’s going to work someday, or it may be that a satellite has to do that observation. If there are gravitational waves from the first epochs of the universe, they’re going to have periods, or cycles, that are stretched to on the order of the age of the universe itself, almost 14 billion years. So that’s the lower limit to the spectrum.

    For another example, there’s a project that’s been going on almost as long as LIGO called the Laser Interferometer Space Antenna Project, or LISA.

    NASA LISA
    ESA/NASA LISA

    It involves lasers beamed between spacecraft with baselines that are up to five million kilometers, not four kilometers, like LIGO’s detection arms now, or even 40 kilometers like what Matt and Nergis want to do someday. LIGO can’t touch LISA’s detection spectrum, covering much longer wavelengths. With LISA, there’s this wide open window with spectacular stuff in it, like binary white dwarf stars going around each other. Another is black holes with tens of thousands to hundreds of thousands of the mass of the Sun, either colliding or having objects bend their orbit around them. You could do very, very careful tests of general relativity with that. I hope these other areas get dragged along by our discovery.

    TKF: Do you think there are any astrophysical objects in our galactic neighborhood that could unleash sizeable gravitational waves detectable by LIGO, or are all the major sources going to be far away?

    Evans: I suggest that we hope that there’s nothing close by. [Laughter] The binary black hole system we detected was 1.5 billion light years distant. That’s very, very far away, and in terms of how much energy was released so quickly, it was the most powerful explosion ever observed. So I think you wouldn’t want that in your neighborhood.

    Mavalvala: But maybe not too close, just within our galaxy…

    Evans: Well, a Milky Way event would probably saturate our detectors, but it’s not like it could hurt us or anything.

    Weiss: Well, I hope you’re right about that! [Laughter] If we ever happen to be around when a supernova goes off, that would be as spectacular as what we have discovered now because we will see everything that is going on deep inside the supernova. Gravitational waves come right out. Nothing scatters these waves, which is the opposite of light that never gets out of the core of the explosion to tell us anything.

    Evans: I hate to get peoples’ hopes up for a supernova because they are so rare, but Rai is absolutely right. If we detect one in our galaxy, it would be a wonderful piece of physics.

    Mavalvala: I’ll add that I hate to get peoples’ hopes up for things we don’t even know how to articulate yet. We don’t fully know what’s out there with this new way of looking at the universe in gravitational waves. So it’s possible that there will be things maybe in our own galactic neighborhood, maybe far away, or maybe both that are just things we have not thought about yet.

    Evans: That’s very true. We’ve heard the loudest possible thing you could imagine go off and we got it, but hey, we’re just getting started.

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  • richardmitnick 10:06 am on January 26, 2016 Permalink | Reply
    Tags: , , space.com, Superfast 'Cannonball' Star,   

    From UCSC via SPACE.com: “Strange Superfast ‘Cannonball’ Star Likely Blasted from Supernova” 

    UC Santa Cruz

    UC Santa Cruz

    January 25, 2016
    Sarah Lewin, Staff Writer at SPACE.com

    dwarf carbon star SDSS J1128

    A star with an unusual history is racing through the galaxy at breakneck speed — most likely blasted away by a supernova and carrying traces of the exploded star.

    The strange runaway star, which is rocketing along at more than 960,000 miles per hour (1.54 million kilometers per hour), is stained in carbon even though it’s too immature to have created the stuff itself, scientists said.

    Kathryn Plant, a senior at the University of California, Santa Cruz (UCSC), presented the new observations earlier this month at the American Astronomical Society’s 227th meeting in Kissimee, Florida. She and her co-authors said the star’s tremendous speed and its carbon signal could be linked.

    “You’re looking at this very, very, very rare star that’s moving at cannonball velocity,” study co-author Bruce Margon, an astronomer at UCSC, told Space.com. “That got us thinking — maybe there’s something about it being a dwarf carbon star that has to do with it having this crazy-high speed.”

    Their top guess is that the speedy star was in a binary system with another star that imbued it with carbon before dying in a massive supernova explosion, shooting the first star out and away. The situation may be similar for several other “cannonball” candidates the researchers have identified.

    That unusual carbon content is the key “extra clue” to the speedy stars’ origin, said Plant, the new work’s lead author.

    “For many stars, we can look at them and see how they’re moving now, but we often don’t have a lot of clues to what they might have been doing in the distant past,” she told Space.com. “Since [the star] carries this material mark, we have a clue to what it was doing in the past.”

    Perplexing stars

    The star in question, called SDSS J112801.67+004034.6 (SDSS J1128 for “short”), was originally measured through the Sloan Digital Sky Survey [SDSS] in March 2000.

    SDSS Telescope
    SDSS telescope at Apache Point, NM, USA

    Along with about 500 others found so far, it seems to fall into the strange stellar category of “dwarf carbon stars.” Different than a “white dwarf,” the super-dense remnant left at the end of a star’s life cycle, a dwarf carbon star appears to be in an early stage of evolution but contains a high level of carbon. That’s odd, because carbon is usually found shrouding red giants, which are in a much later stage.

    “The mere existence of these stars is kind of perplexing, because they are adolescent stars — they are stars at about the same evolutionary stage as our sun,” Margon said. “There shouldn’t be such a thing as a dwarf carbon star, because there’s no way for that star to have created carbon given where it is in its life cycle.”

    Instead, researchers theorize that each of these stars once orbited together with another star, a companion, which was in a later part of its life cycle and had already produced carbon. If the binary stars orbited closely enough, one star’s carbon could transfer to the other.

    The transfer of mass could happen peacefully over time — “a gentle wind puffed off for millions of years,” Margon said — but the two stars’ association might end on much more violent terms when the more mature star explodes into a supernova.

    Smoking guns

    SDSS J1128 first came to the researchers’ attention because of how quickly it was speeding away from Earth, which researchers calculated based on distortion in the wavelengths of light it put out in that first measurement. They followed up by measuring the star with Hawaii’s Keck Observatory in April 2015, and found that it was still moving away at about the same speed.

    Keck Observatory
    Keck Observatory Interior
    Keck

    But not only that: After looking at the star’s location from surveys over many years (the earliest was in 1955), the research team realized that it was visibly sweeping across the sky as well, not just fleeing from Earth. That implied that the star was dimmer and close, rather than far away and very bright.

    Researchers know stars can pick up incredible speed by whipping around the supermassive black hole in the Milky Way’s center, so this was one of the first possible explanations for this star’s great velocity. But once the collaborators calculated its approximate location — between 3,000 and 10,000 light-years away — and its speed compared with the center of the galaxy, it became clear that the star was not on that type of trajectory.

    “Even though we don’t have one exact number, we can understand what it’s most likely doing,” Plant said. “We can rule out […] certain motions that are not possible, and that lets us conclude that it’s not coming from the center of the galaxy, which is one of the main questions we wanted to answer, and also lets us conclude that it is bound to the galaxy but it’s on an extremely eccentric orbit.”

    So they turned to the supernova possibility. Other stars’ speeds have occasionally been attributed to the driving force of a supernova, the researchers said, but evidence has not been conclusive.

    “This thing has a different set of smoking guns that are pointing towards that evidence,” Margon said. “It’s the thing science fiction emerges from: You have a peaceful star minding its own business, its companion goes ‘kerblooie’ and completely demolishes itself and shoots this thing off like a cannonball,” he added. “We’re advancing this as a candidate for that [scenario].”

    Not so alone

    To find out more about the high-speed star, researchers can take follow-up measurements to check for tiny variations in the speed at which it’s moving away from Earth, as well as more about its chemical composition. Ultimately, projects like Europe’s galaxy-mapping [ESA] Gaia mission could provide even more precise data about the star’s location, if it falls within the satellite’s view, the researchers said.

    ESA Gaia satellite
    ESA/Gaia

    The star is one of a few candidates the researchers found for this extreme motion — it had the fastest velocity of the bunch relative to Earth, but the others could prove even faster when measured in the context of the entire galaxy. Comparing the traits of all those “cannonball” stars could help solidify the supernova explanation or suggest another mechanism.

    “The fact that this is a super-high-velocity star isn’t going to go away,” Margon said. “The interpretation might change.”

    See the full article here .

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    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

     
  • richardmitnick 7:59 am on January 26, 2016 Permalink | Reply
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    From SPACE.com: “Mysteriously Powerful Particles from Solar Explosions Unveiled in New Study” 

    space-dot-com logo

    SPACE.com

    January 25, 2016
    Calla Cofield

    Solar eruption 2012 by NASA's Solar Dynamic Observatory SDO
    A photo of a solar eruption from Oct. 14, 2012, as seen by NASA’s Solar Dynamic Observatory. Credit: NASA/SDO

    NASA SDO
    NASA/SDO

    A couple of times a month — sometimes more, sometimes less — an explosion goes off on the surface of the sun, releasing energy that’s equal to millions of hydrogen bombs.

    Mind boggling as that number is, this tremendous energy output cannot explain how material that is spit out by these explosions gets ramped up to nearly the speed of light. It’s like expecting a golf cart motor to power a Ferrari.

    In a new study, researchers provide a first-of-its-kind look under the hood of these solar eruptions, taking specific aim at the physical process that accelerates the superfast particles.

    Explosions on the sun

    There are currently 18 NASA space missions dedicated to studying our nearest star and its effect on the solar system. Some of these satellites stare directly at the sun almost nonstop, providing a 24/7 stream of images of the sun’s swirling, churning surface.

    When a solar eruption happens, these satellites also see the incredibly bright flashes of light that are called solar flares. Occasionally, the eruptions also hurl a cloud of extremely hot and electrically charged gas (called plasma) out into space. The expelled plasma is called a coronal mass ejection, or CME for short.

    A solar explosion releases roughly the same amount of energy that would come from “millions of 100-megaton hydrogen bombs,” according to NASA, where one hundred megatons equal to one hundred million metric tons of TNT.

    While that certainly sounds impressive, it’s hard to imagine something so enormous. The best way to understand the colossal nature of these events might be to consider an image taken by NASA that shows a particularly massive CME. For comparison, a snapshot of the Earth (to scale) is placed next to this great, flaming ribbon. The planet looks like a daisy in the path of a flamethrower.

    A solar explosion releases roughly the same amount of energy that would come from “millions of 100-megaton hydrogen bombs,” according to NASA, where one hundred megatons equal to one hundred million metric tons of TNT.

    Shockingly fast

    When an airplane breaks the sound barrier — physically overtaking the sound waves traveling in front of it — it creates a shock wave, and a deafening sonic boom. The boom is evidence that the shock wave is a source of energy.

    Bin Chen, a researcher at the Harvard-Smithsonian Center for Astrophysics is the lead author on a new research paper that provides the first solid observational evidence that ultraspeedy particles released during a solar eruption are accelerated by a kind of stationary shock wave called a “termination shock.”

    One of the intriguing elements of solar eruptions is that, unlike most explosions on Earth, they aren’t chemically driven. Rather, these sunshine bombs are detonated by a rapid release of magnetic energy. The same force that makes a magnet stick to a refrigerator or makes a compass needle point north is also responsible for these massive belches of light and material.

    The solar eruptions that create solar flares and CMEs occur when one of the sun’s magnetic-field lines break, and rapidly reconnects, near the surface. During the explosion, plasma is flung out into space, but others go back down toward the surface at incredibly high speeds, where they crash into more magnetic-field loops — kind of like a waterfall crashing into the surface of a pond. At the point of collision, a termination shock forms in the electrically charged plasma.

    “Charged particles that cross a [termination] shock can pick up the energy from the shock and get faster and faster. That’s how shock acceleration works,” Bin told Space.com.

    Chen and his coauthors saw evidence of this termination shock during a solar flare on March 3, 2012, using the Karl G. Jansky Very Large Array (VLA) in New Mexico.

    NRAO VLA
    Karl G. Jansky Very Large Array (VLA)

    The recently upgraded telescope was beneficial for two reasons. First, it detects radio waves, which means it isn’t overwhelmed by the brightest flashes of light emitted during a solar flare. But looking at a solar flare radio frequencies does reveal the particles accelerated by the termination shock.

    Second, the telescope can effectively take around 40,000 images per second. It does this by capturing thousands of radio frequencies at the same time. The frequencies are then separated into individual “images.” Chen told Space.com that in order to see termination shock in action, it was necessary to collect that many images for about 20 minutes.

    “So if you do the math, that’s millions and millions of images [you need] in order to extract the information,” Chen said. “That’s a new capability provided by the upgraded VLA.”

    Chen said the new findings don’t necessarily mean that termination shocks are responsible for accelerating particles in all solar flares. He said he and his colleagues would like to conduct further observations to find out if this is the case in all shocks, or only a subset.

    The termination shock explanation has been part of the “standard” solar-flare theory for years, but there hasn’t been “convincing” observational evidence to back it up, Chen said. Chen’s comment was confirmed by Edward DeLuca, a senior astrophysicist at the Smithsonian Astrophysical Observatory, which is part of the Harvard-Smithsonian Center for Astrophysics (DeLuca works in the same department as Chen, but was not involved with the new research.)

    “[The new result] reveals that we’re on the right track with the standard-flare model,” DeLuca said.

    Look out for powerful particles

    All those NASA satellites studying the sun are not just working to create mesmerizing images; they’re also there to help protect Earth. Solar flares and coronal mass ejections pose a hazard to the planet. The particles they eject can damage satellites and solar panels, and could pose a serious threat to astronauts doing spacewalks outside the International Space Station, on the moon or Mars.

    They can even cause surges in power grids on the ground. In 1989, a CME caused a blackout across the entire province of Quebec, Canada.

    The superfast particles are of particular worry, because their high speeds mean they can penetrate more layers of material than their “slower” counterparts. When those particles penetrate a piece of solid-state equipment, they can cause a “bit flip” — which could not only damage the equipment but also change what it does.

    “If that little flip of the bit means a computer command that normally says, ‘keep taking snapshots of the sun,’ instead says ‘shut down the spacecraft,’ that’s bad,” Young said. “So a lot of times, if there is a large particle event, spacecraft operators will often put their spacecraft into what’s called a ‘safe mode.'”

    That reaction has to happen fast. Light can travel from the sun to the earth in 8 minutes, so the solar energetic particles can reach an orbiting satellite in about 10 to 20 minutes, Young said. Coronal mass ejections leave a little more time, but a delayed response can mean serious consequences.

    For that reason, scientists are trying to get better at predicting when solar flares and CME’s will occur and how intense they will be.

    DeLuca said the new understanding of termination shock will not, most likely, be immediately useful for improving forecasting of solar explosions. But it is a piece of the solar-flare puzzle, and he said it will be incorporated into “next-generation” solar-weather technology and prediction techniques. It’s one more step toward helping humans ride out the solar storm.

    See the full article here .

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  • richardmitnick 1:02 pm on January 9, 2016 Permalink | Reply
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    From SPACE.com: “Worldwide Telescope Network Will Take Best-Ever Images of Black Holes” 

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    SPACE.com

    January 08, 2016
    Calla Cofield

    Temp 1
    An image from a simulation showing how matter might be moved around in the extreme environment around a black hole. The simulations will be compared to observational data collected by the Event Horizon Telescope, which will be increasing its sensitivity in 2017 and 2018.
    Credit: Özel/Chan

    Get ready for your close-up, black holes: The Event Horizon Telescope (EHT), which will take some of the best images of black holes ever captured by humans, is ramping up its worldwide network of telescopes.

    Event Horizon Telescope map
    Event Horizon Telescope map. Credit U Arizona

    By 2018, the EHT will be an observatory that harnesses the power of nine telescopes around the world, including ones in Chile, Arizona, Hawaii, Antarctica and Greenland. These instruments will work together to get higher-resolution images than any of these scopes can achieve alone. The target of their observations will be black holes — scientists hope to see the material moving around these dark monsters, as well as the shadow of the black hole itself.

    Telescopes in The EHT:

    ALMA
    ALMA Array

    South Pole Telescope
    South Pole Telescope

    ESO/APEX
    ESO APEX

    Large Millimeter Telescope in Mexico
    Large Millimeter Telescope Alfonso Serrano

    Submillimeter Telescope in Arizona
    U Arizona Submillimeter Telescope

    Combined Array for Research in Millimeter-wave Astronomy in California
    CARMA Array

    Harvard Smithsonian Submillimeter Array
    SMA Submillimeter Array

    James Clerk Maxwell Telescope in Hawaii
    James Clerk Maxwell Telescope

    Institute for Radio Astronomy Millimetrique (IRAM) telescopes in Spain and France
    IRAM 30m Radio telescope

    “One thing that could excite the public almost as much as a Pluto flyby would be a picture of a black hole, up close and personal,” Feryal Ӧzel, a professor of astronomy and astrophysics at the University of Arizona, said during a talk here at the 227th meeting of the American Astronomical Society, where a few thousand astronomers and astrophysicists have gathered to discuss the latest news in the field. (Ӧzel’s comment was made in reference to the massive public interest in the images captured by NASA’s New Horizons probe,

    NASA New Horizons spacecraft
    NASA/New Horizons spacecraft

    which flew by the dwarf planet last July.)

    Other telescopes have studied black holes in the past, but the goal of the EHT is to take images that surpass the resolution of any previous black-hole snapshots. With that information, scientists would be able to see the area around a black hole — a place where the pull of gravity is so extreme that very strange things happen.

    Temp 2
    Images made from simulations showing how matter might move around in the extreme environment around a black hole. Scientists hope to use the simulations to better understand observations taken by the Event Horizon Telescope.
    Credit: Özel/Chan

    For example, the black hole at the center of the galaxy known as Messier 87 has a massive, narrow jet of material, roughly 5,000 light-years long, spewing away from it.

    2
    Messier object 87 by Hubble space telescope
    18 August 2009

    NASA Hubble Telescope
    NASA/ESA Hubble

    In contrast, the black hole at the center of the Milky Way — Sagittarius A* — has very little matter around it and no jets.

    4
    Sagittarius A*. This image was taken with NASA’s Chandra X-Ray Observatory. Ellipses indicate light echoes. source
    23 July 2014

    NASA Chandra Telescope
    NASA/Chandra

    In galaxies known as active galactic nuclei (AGNs), black holes accelerate huge clouds of material around them, and radiate more light than the entire Milky Way galaxy. What leads to such a drastic difference between these objects? With EHT, Ӧzel said, scientists may finally be able to answer that question.

    “Is it the magnetic field structure that is different? Is it the spin that is different? Or is it something else about the accretion flow that is different?” Ӧzel said. “This will open a brand-new window into studying accretion physics.”

    And then there’s [Albert]Einstein. His theory of general relativity has been tested using observations in Earth’s solar system — for example, the way light bends around the sun — and beyond. But there are few cosmic environments as extreme as the one around a black hole, where the gravity can be millions of times stronger than it is around a star. As a result, the EHT will reveal the effects of gravity (which are described by the theory of relativity) “on scales that have never been probed before,” said Ӧzel, who is a scientist on the EHT project team and is leading some of the theoretical work that will be combined with the observations.

    “Get to the edge of a black hole, and the general relativity tests you can perform are qualitatively and quantitatively different,” Ӧzel said.

    Understandably, Ӧzel and other black-hole scientists are eager to start getting data from EHT. One of the major requirements of imaging black holes in such high resolution is to have a very large telescope. In fact, Ӧzel said that achieving the resolution of EHT effectively requires a telescope the size of the Earth.

    “Of course nobody would fund an Earth-sized telescope,” Ӧzel said. But the “next-best thing” is to combine observations from multiple telescopes on the surface of the Earth that are separated by very large distances, Ӧzel said [interferometry]. With this technique, scientists can observe an object in significantly higher resolution than the telescopes could achieve alone — effectively giving scientists an “Earth-size” telescope.

    The first data from the EHT project were collected in the mid-2000s, by three telescopes — one each in Hawaii, Arizona and California. The group collaborated to look at the black hole at the center of the Milky Way galaxy, called Sagittarius A*. In 2014, the collaboration added the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to its array, and doubled its resolution, according to the EHT website.

    Six telescopes in the EHT array are already taking data, and a total of nine are expected to be contributing to the project by 2018, according to Shep Doeleman, principal investigator for EHT.

    Early in 2015, the collaboration added the South Pole Telescope to its array, which connected the other telescopes such that the EHT effectively spanned the entire Earth. In 2017, the EHT will be able to make observations with ALMA that will boost its sensitivity by a factor of 10, Doeleman told Space.com in an email. In 2018, an additional telescope will join the group from Greenland.

    “One of the innovative aspects of the EHT is that we use existing telescopes at the highest altitudes (where they are above most of the atmosphere) and outfit them with specialized instrumentation that enables us to link them together,” Doeleman said. “So we don’t build new dishes, and we leverage over a [billion dollars] of existing telescopes.”

    However, there are still obstacles, he noted. “Last year, one of the facilities participating in the EHT had to close due to lack of funding,” Doeleman said. “We can still do all the EHT [work] planned because new sites are coming online, but we remain ‘en guard’ for threats against EHT sites.”

    See the full article here .

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  • richardmitnick 10:57 am on January 7, 2016 Permalink | Reply
    Tags: , , , space.com   

    From Space.com: “Visible Light from a Black Hole Spotted by Telescope, a First” 

    space-dot-com logo

    SPACE.com

    January 06, 2016
    Charles Q. Choi

    For the first time, astronomers have seen dim flickers of visible light from near a black hole, researchers with an international science team said. In fact, the light could be visible to anyone with a moderate-size telescope.

    These dramatically variable fluctuations of light are yielding insights onto the complex ways in which matter can swirl into black holes, scientists added. The researchers also released a video of the black hole’s light seen by a telescope. In a statement, they added that such light from an active black hole could be spotted by an observer with a 20-cm telescope.

    Temp 1
    This image still from a video by scientists studying the black hole V404 Cygni located about 7,800 light-years from Earth shows visible light that could be viewable by stargazers with a medium-size telescope. Credit: Michael Richmond/Rochester Institute Of Technology

    Anything falling into black holes cannot escape, not even light, earning black holes their name. However, as disks of gas and dust fall or accrete onto black holes — say, as black holes rip apart nearby stars — friction within these accretion disks can superheat them to 18 million degrees Fahrenheit (10 million degrees Celsius) or more, making them glow extraordinarily brightly.

    Scientists discovered accreting black holes in the Milky Way more than 40 years ago. Previous research suggested that the accretion disks of black holes can have dramatic effects on galaxies. For instance, streams of plasma known as relativistic jets that spew out from accreting black holes at near the speed of light can travel across an entire galaxy, potentially shaping its evolution. However, much remains unknown about how accretion works, since matter can behave in very complex ways as it spirals into black holes, said study lead author Mariko Kimura, an astronomer at Kyoto University in Japan, and her colleagues.

    To learn more about the mysterious process of accretion, researchers in the new study analyzed V404 Cygni, a binary system composed of a black hole about nine times the mass of the sun and a companion star slightly less massive than the sun. Located about 7,800 light-years away from Earth in the constellation Cygnus, the swan, V404 Cygni possesses one of the black holes closest to Earth.

    After 26 years during which the system was dormant, astronomers detected an outburst of X-rays from V404 Cygni in 2015 that lasted for about two weeks. This activity from the accretion disk of V404 Cygni’s black hole briefly made it one of the brightest sources of X-rays seen in the universe.

    Following this outburst, the researchers detected flickering visible light from V404 Cygni, whose fluctuations varied over timescales of 100 seconds to 150 minutes. Normally, astronomers monitor black holes by looking for X-rays or gamma-rays.

    “We find that activity in the vicinity of a black hole can be observed in optical light at low luminosity for the first time,” Kimura told Space.com. “These findings suggest that we can study physical phenomena that occur in the vicinity of the black hole using moderate optical telescopes without high-spec X-ray or gamma-ray telescopes.”

    Similar variable flickering was seen in the X-ray emissions from another black hole system, GRS 1915+105, located about 35,900 light-years away from Earth in the constellation Aquila, the eagle. GRS 1915+105 experiences high levels of accretion. As such, researchers previously suggested the system’s variable flickering was due to instabilities that can occur in accretion disks when they get very massive.

    However, the accretion rates at V404 Cygni are at least 10 times lower than those seen at other black hole systems that have similar oscillations. This suggests that high accretion rates are not the main factor behind this variable flickering, the researchers said.

    Instead, the scientists noted that in both V404 Cygni and GRS 1915+105, the black holes and their companion stars are relatively far apart, which permits a large accretion disk to form. In such large disks, matter from the outer disk might not flow in a steady manner to the inner disk near the black hole, the researchers said. As such, the researchers suggest that accretion onto these black holes can become unstable and fluctuate wildly. This sporadic activity, they said, could then explain the oscillating patterns of light from these black holes.

    The scientists said they hope that worldwide coordination will permit future research to better understand the nature of these extreme events.

    “Thanks to international cooperation, we could get extensive optical observational data in our research with 35 telescopes at 26 locations,” Kimura said. “We would like more people to join in optical observations of black-hole binaries.”

    Kimura and her colleagues detailed their findings in the Jan. 7 issue of the journal Nature.

    See the full article here . In the Nature article you can find the science team.

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