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  • richardmitnick 10:46 am on May 9, 2020 Permalink | Reply
    Tags: "Survival in the Atacama Desert", , , Chroococcidiopsis – a cyanobacteria commonly found in deserts – and gypsum in Chile’s Atacama Desert., COSMOS,   

    From COSMOS: “Survival in the Atacama Desert” 

    Cosmos Magazine bloc

    From COSMOS

    05 May 2020
    Nick Carne

    1
    Gypsum rocks in Chile’s Atacama Desert. Credit:Jocelyne DiRuggiero

    It’s not quite life on Mars, but it may be a pointer.

    US researchers have shown that, as some had suspected, microorganisms can survive in the harshest of conditions by extracting water from the rocks they colonise.

    A team from the University of California (UC) and Johns Hopkins University (JHU) studied interactions between Chroococcidiopsis – a cyanobacteria commonly found in deserts – and gypsum in Chile’s Atacama Desert.

    1
    An international team of scientists has found that a strange type of bacteria can turn light into fuel in incredibly dim environments. Similar bacteria could someday help humans colonize Mars and expand our search for life on other planets, researchers said in a statement released with the new work.

    Organisms called cyanobacteria absorb sunlight to create energy, releasing oxygen in the process. But until now, researchers thought these bacteria could absorb only specific, higher-energy wavelengths of light. The new work reveals that at least one species of cyanobacteria, called Chroococcidiopsis thermalis — which lives in some of the world’s most extreme environments — can absorb redder (less energetic) wavelengths of light, thus allowing it to thrive in dark conditions, such as deep underwater in hot springs. [Extreme Life on Earth: 8 Bizarre Creatures]

    “This work redefines the minimum energy needed in light to drive photosynthesis,” Jennifer Morton, a researcher at Australian National University (ANU) and a co-author of the new work, said in the statement. “This type of photosynthesis may well be happening in your garden, under a rock.” (In fact, a related species has even been found living inside rocks in the desert.)

    When grown in far-red light, this cyanobacteria, called Chroococcidiopsis thermalis, can still photosynthesize where others falter. Credit: T. Darienko/CC BY-SA 4.0

    Or below it, to be precise. The Chroococcidiopsis exist beneath a thin layer of rock that gives them a measure of protection against the high solar irradiance, extreme dryness and battering winds in what is the world’s driest non-polar region.

    When gypsum samples were studied back in the lab, the most striking discovery was that the microorganisms change the very nature of the rock. By extracting water, they cause a phase transformation of the material – from gypsum to anhydrite, a dehydrated mineral.

    Intrigued, the researchers ran some experiments, allowing the organisms to colonise half-millimetre cubes of rock, called coupons, under two different conditions: one in the presence of water, to mimic a high-humidity environment, and the other completely dry.

    Amid moisture, they found, the gypsum did not transform to the anhydrite phase.

    The cyanobacteria “didn’t need water from the rock, they got it from their surroundings”, says David Kisailus, from UC Irvine. “But when they were put under stressed conditions, the microbes had no alternative but to extract water from the gypsum, inducing this phase transformation in the material.”

    Kisailus’s team used a combination of advanced microscopy and spectroscopy to examine the interactions between the biological and geological counterparts, finding that the organisms bore into the rock by excreting a biofilm containing organic acids.

    UCI’s Wei Huang then used a modified electron microscope equipped with a Raman spectrometer to discover that the cyanobacteria used the acid to penetrate the gypsum in specific crystallographic directions – only along certain planes where they could more easily access the water existing between faces of calcium and sulfate ions.

    “Researchers have suspected for a long time that microorganisms might be able to extract water from minerals, but this is the first demonstration of it,” says JHU biologist Jocelyne DiRuggiero

    “This is an amazing survival strategy for microorganisms living at the dry limit for life, and it will guide our search for life elsewhere.”

    The findings are reported in a paper in the journal Proceedings of the National Academy of Science.

    See the full article here .


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    • Skyscapes for the Soul 4:37 pm on May 9, 2020 Permalink | Reply

      A post about life in the Atacama desert is of great interest. It had long been a place on my bucket list – until Murray Foote visited and mentioned the altitude. Ugh, this low desert rat would not survive such heights. Nice though to hear that other researchers can bring me interesting news from there.

      Like

  • richardmitnick 12:33 pm on May 8, 2020 Permalink | Reply
    Tags: "Scanning with golden bow ties", , , , COSMOS, , Terahertz scanners   

    From COSMOS: “Scanning with golden bow ties” 

    Cosmos Magazine bloc

    From COSMOS

    08 May 2020
    Phil Dooley

    Detectors would operate in terahertz region.

    1
    Credits: DIMITAR JEVTICS

    Australian and British physicists have unveiled their design for a high-precision detector they say could enable a new generation of safe compact scanners.

    As described in a paper in the journal Science, it is based around tiny “bow ties”, each comprising two triangles of solid gold connected by two nanowires.

    This design allows it to operate in the terahertz region of the electromagnetic spectrum, between microwaves and infrared. Terahertz scanning offers a safer low-energy alternative to X-rays: it is not powerful enough to ionise materials.

    However, it still penetrates materials such as plastics, wood and paper, is absorbed by water, and is reflected by metals, giving the technology the capability to analyse a wide range of samples.

    The bow ties also are able to detect the polarisation of the terahertz radiation, which adds another dimension to the detector’s versatility.

    “The polarisation gives you much more useful information, especially about biological molecules, for example their chirality,” says Chennupati Jagadish from the Australian National University (ANU).

    “Complex molecules have their own terahertz fingerprints, so this technology can be used for finding cancer biomarkers, locating explosives or measuring moisture levels in crops.”

    The device is the result of a collaboration between ANU and Oxford University in England and Scotland’s Strathclyde University.

    Importantly, the researchers say, it overcomes a limitation in the resolution, or detail, of conventional terahertz imaging, which is linked to its millimetre-scale wavelength – a million times larger than X-rays, with nanometre-scale wavelengths.

    The design gets around this limitation with the microscopic scale of the bow ties. The pair of nanowires at their heart are indium phosphide wires one hundredth the size of a human hair: around 280 nanometres in diameter and ten micrometres long.

    Although each detector is much smaller than the terahertz waves (around 300 microns), an array of bow ties can be used to create a near-field image that bypasses the diffraction limit of the terahertz radiation’s wavelength.

    To detect the polarisation of the radiation, the team combined two bow ties, set at right angles to each other, with their central nanowires crossing but not in contact – one bow tie is set slightly above the other.

    Although a simplistic-sounding design, the vertically offset configuration took three years of collaboration to devise and manufacture.

    The nanowires were created at ANU, the triangles were added at Oxford as antennae to boost the signal level (gold being the obvious choice due to its high conductivity), then the devices were assembled at Strathclyde.

    The team is now developing nano-scale electronics to connect to the detector, so the whole device can be built onto a single chip, in contrast with existing bulky terahertz scanners.

    See the full article here .


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  • richardmitnick 10:07 am on April 27, 2020 Permalink | Reply
    Tags: "Super-rotation and Venus’ atmosphere", , , , , COSMOS, Super-rotation is maintained by a combination of solar heating-driven thermal tides; planetary waves and atmospheric turbulence.,   

    From COSMOS: “Super-rotation and Venus’ atmosphere” 

    Cosmos Magazine bloc

    From COSMOS

    27 April 2020
    Nick Carne

    Researchers suggest it’s due to tides, waves and turbulence.

    1
    Schematic illustration on how the super-rotation of Venus’ atmosphere is maintained. See full explanation below story.
    Credit: Planet-C project team. In the schematic illustration above, in the cloud layer of Venus a vertical and north-south circulation, called the meridional circulation, exists (white arrows) to transport heat from low latitudes to high latitudes, because sunlight is absorbed more at low latitudes.

    This circulation also transports the angular momentum, which corresponds to the strength of the circulating winds (yellow arrows), to decelerate the super-rotation. The deceleration is compensated by the acceleration by the thermal tide, which transports angular momentum both horizontally and vertically (red arrows).

    Other waves and turbulence work oppositely but weakly at low latitudes (blue allows), while they play an important role at mid-latitudes (pale blue arrows; to transport the angular momentum to shortcut the meridional circulation).

    The combination of these effects manifests a system to effectively transport heat across the globe by the combination of the slow poleward heat transport by the meridional circulation and the fast heat transport to the night-side by the meridional circulation. Such a dual circulation system might present on tidally locked exo-planets to reduce temperature differences over them.

    Scientists tracking the thick clouds of Venus’ rapidly rotating atmosphere say they have gained new insights into the forces that drive atmospheric super-rotation – a phenomenon in which an atmosphere rotates much more quickly than the solid planetary body below.

    Using observations from the JAXA spacecraft Akatsuki, which has been orbiting Venus since 2015, they suggest super-rotation is maintained by a combination of solar heating-driven thermal tides, planetary waves and atmospheric turbulence.

    JAXA/AKATSUKI

    The work by a team led by Takeshi Horinouchi from Japan’s Hokkaido University is described in a paper in the journal Science.

    Venus moves slowly – its surface takes 243 Earth days to complete one rotation – but its atmosphere spins at nearly 60 times that speed, whipping around the planet in 96 hours.

    This super-rotation increases with altitude, taking only four days to circulate around the entire planet towards the top of the cloud cover. Heat is transported from the planet’s dayside to nightside, reducing the temperature differences between the two hemispheres.

    Horinouchi and colleagues note that for this phenomenon to occur, a continuous redistribution of angular momentum is needed to overcome friction with the planet’s surface, although neither the source of this momentum nor how it’s maintained are known.

    They report that by using ultraviolet images and thermal infrared measurements taken by Akatsuki, they tracked the motion of clouds and used them to map Venus’ winds, which provided a consistent picture of its angular momentum balance at the cloud-top level.

    They could then estimate the atmospheric forces sustaining the planet’s super-rotating atmosphere. Their results suggest the required angular momentum is provided through thermal tides, driven by solar heating near the planet’s equator, and is opposed by planetary-scale waves (called Rossby waves) and large-scale atmospheric turbulence.

    In a complementary Perspective in the journal [Science], Sebastion Lebonnois from Laboratoire de Meteorologie Dynamique, Paris, says the research provides “an important piece of the super-rotation puzzle” but suggests “the question of whether their analysis presents a complete picture of the angular momentum balance may still be open”.

    “The observation and analysis focus on only one level of the thick atmosphere of Venus,” he writes. “The possibility remains that the multiple wave activities and their impact on this very sensitive balance may be different at other levels within the 20-km-thick cloud layer.”

    See the full article here .


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  • richardmitnick 11:46 am on April 2, 2020 Permalink | Reply
    Tags: "How we can restore marine life by 2050", , COSMOS, , Fishing below an ocean's maximum yield allows faster recovery of fish stocks.   

    From COSMOS: “How we can restore marine life by 2050” 

    Cosmos Magazine bloc

    From COSMOS

    02 April 2020
    Natalie Parletta

    1
    Fishing below an ocean’s maximum yield allows faster recovery of fish stocks.
    Manu San Felix, National Geographic

    An international team of scientists has painstakingly mapped out positive actions that could return the planet’s marine life to its abundant glory over the next three decades.

    Writing in the journal Nature, they warn that the ocean’s capacity to sustain human wellbeing – by mitigating climate change and providing food, water and oxygen – is at a critical junction.

    “We are at a point where we can choose between a legacy of a resilient and vibrant ocean or an irreversibly disrupted ocean,” says lead author Carlos Duarte from the King Abdullah University of Science and Technology, Saudi Arabia.

    Indeed, the United Nations Sustainable Development Goal 14 recognises the urgent need to “conserve and sustainably use the oceans, seas and marine resources for sustainable development”.

    And it is achievable, the authors say. “Rebuilding marine life represents a doable grand challenge for humanity, an ethical obligation and a smart economic objective to achieve a sustainable future.”

    Although human activities have had devastating impacts on marine life over the 20th century, the team drew on resilient responses of sea creatures, habitats and ecosystems to conservation efforts to demonstrate how they can be revived.

    These include the spectacular recovery of humpback whales (Megaptera novaeangliae) in Australia, sea otters (Enhudra lutris) in West Canada and Baltic Sea grey seals (Halichoerus grypus) from the brink of extinction.

    Other examples include large-scale habitat restoration of mangroves, reduction of organic pollutants and efforts to manage and recover fish stocks.

    Through success stories of ocean conservation and recovery trends, the researchers identify nine factors central to reviving marine life, salt marshes, mangroves, seagrasses, coral reefs, kelp, oyster reefs, fisheries, megafauna and the deep sea.

    They outline six complementary interventions called “recovery wedges” that include a suite of strategies under the themes of protecting species and spaces, harvesting prudently, restoring habitats, reducing pollution and mitigating climate change.

    Recommended actions include opportunities, benefits, possible roadblocks and remedial initiatives, providing a tangible roadmap to deliver a healthy ocean. But it’s not a smorgasbord that can be picked at selectively or passively.

    The authors stress that the goals need to be adopted across the board, and that the focus should be not just conservation but actively reviving dwindling species and ecosystems to sustainably feed and support the growing human population.

    Importantly, rebuilding marine life abundance can only succeed if the most ambitious goals within the Paris Agreement are met; impacts from climate change already limit the scope for rebuilding tropical corals to a partial recovery.

    Success relies heavily on a committed, global partnership of governments and societies aligned with the goal, as well as a significant financial investment. But the researchers report that the ecological, economic and social gains will be far-reaching.

    The review is well-timed for this year’s G20 summit in Saudi Arabia, where nations will consider their actions to conserve biodiversity beyond 2020.

    “We have a narrow window of opportunity to deliver a healthy ocean to our grandchildren’s generation, and we have the knowledge and tools to do so,” says Duarte.

    “Failing to embrace this challenge – and in so doing condemning our grandchildren to a broken ocean unable to support high-quality livelihoods – is not an option.”

    See the full article here
    .


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  • richardmitnick 11:14 am on April 2, 2020 Permalink | Reply
    Tags: "When there was rainforest near the South Pole", COSMOS, CT scans revealed a dense network of roots throughout the soil layer with countless traces of pollen and spores and remnants of flowering plants., German and British scientists have found unexpected fossil traces of a temperate rainforest near the South Pole from 90 million years ago., If it became so warm in the Antarctic back then what caused the climate to subsequently cool so dramatically to form ice sheets again?, The annual mean air temperature 800 kilometres from the South Pole was about 12 degrees Celsius – roughly the same as the Australian city of Hobart today., The mid-Cretaceous period – considered the age of the dinosaurs – was the warmest in the past 140 million years., The samples come from a core of sediment taken from the seabed near West Antarctica's Pine Island Glacier in 2017.   

    From COSMOS: “When there was rainforest near the South Pole” 

    Cosmos Magazine bloc

    From COSMOS

    02 April 2020
    Nick Carne

    1
    An artist’s impression of temperate rainforest in West Antarctica 90 million years ago.
    Alfred-Wegener-Institute/J. McKay. Creative Commons licence CC-BY 4.0

    German and British scientists have found unexpected fossil traces of a temperate rainforest near the South Pole from 90 million years ago.

    Writing in the journal Nature, they say their analysis of pristinely preserved soil from the Cretaceous period suggests prehistoric rainforests in Antarctica were similar to those in New Zealand today.

    The samples come from a core of sediment taken from the seabed near West Antarctica’s Pine Island Glacier in 2017.

    “During the initial shipboard assessments the unusual colouration of the sediment layer quickly caught our attention; it clearly differed from the layers above it,” says first author Johann Klages, a geologist from Germany’s Alfred Wegener Institute (AWI).

    CT scans revealed a dense network of roots throughout the soil layer, with countless traces of pollen and spores, and remnants of flowering plants. The researchers say they could even make out individual cell structures.

    The mid-Cretaceous period – considered the age of the dinosaurs – was the warmest in the past 140 million years. Sea levels were 170 metres higher than today and sea surface temperatures in the tropics are believed to have been as high as 35 degrees Celsius.

    Until now, however, little has been known about the environmental conditions south of the Polar Circle.

    Palaeoecologist Ulrich Salzmann, from Northumbria University, UK, used the preserved pollen and spores to reconstruct the past vegetation and climate, revealing that “the coast of West Antarctica was, back then, a dense temperate, swampy forest…”

    The team’s analysis suggests that, at the time, the annual mean air temperature 800 kilometres from the South Pole was about 12 degrees Celsius – roughly the same as the Australian city of Hobart today.

    Summer temperatures averaged 19 degrees and water temperatures in rivers and swamps reached up to 20. This was despite a four-month polar night when there was no sunlight.

    The amount and intensity of rainfall in West Antarctica was similar to that in Wales today.

    Such climate conditions, the researchers say, could only be achieved with a dense vegetation cover on the Antarctic continent and the absence of any major ice sheets in the South Pole region.

    Carbon dioxide concentration in the atmosphere was also far higher than previously assumed.

    “Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1000 ppm [parts per million],” says AWI climate modeller Gerrit Lohmann.

    “But in our model-based experiments, it took concentration levels of 1120 to 1680 ppm to reach the average temperatures back then in the Antarctic.”

    Accordingly, the researchers say, the study shows both the enormous potency of carbon dioxide and how essential the cooling effects of today’s ice sheets are.

    “We now know that there could easily be four straight months without sunlight in the Cretaceous, but because the carbon dioxide concentration was so high, the climate around the South Pole was nevertheless temperate, without ice masses,” says geoscientist Torsten Bickert from the University of Bremen.

    The big question now is: if it became so warm in the Antarctic back then, what caused the climate to subsequently cool so dramatically to form ice sheets again? “Our climate simulations haven’t yet provided a satisfactory answer,” says Lohmann.

    See the full article here .


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  • richardmitnick 12:32 pm on December 9, 2019 Permalink | Reply
    Tags: "Part of a disCERNing crowd", , Australian astrophysicist Martin White discusses life with and around the Large Hadron Collider., , COSMOS, , ,   

    From COSMOS Magazine: “Part of a disCERNing crowd” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    09 December 2019

    Australian astrophysicist Martin White discusses life with and around the Large Hadron Collider.

    1
    An aerial view of the CERN site, enlivened by Martin White’s hand-written annotations. Credit: Atlas experiment / CERN

    It’s lunchtime, and I am standing with a colleague under the main site of the CERN laboratory, trying to work out whether to go right or left.

    With the rainy Geneva winter in full swing, he informs me that he’s found a hidden entrance to a network of tunnels under the foyer of CERN’s main building and has worked out how to get to the fabled Restaurant 2 without getting wet.

    All we have to do is follow his secret route through the tunnels, which it transpires is so secret that he himself has forgotten it. After half an hour squeezing past hanging cables and scary radiation warnings, we emerge starving exactly where we started out.

    This is life at CERN in a nutshell – an endless search for the unknown conducted in a spirit of frivolity by permanently hungry practitioners. Established in 1954, the European Organisation for Nuclear Research (CERN) hosts the largest particle accelerator ever built by humankind, named, rather appropriately, the Large Hadron Collider (LHC).

    It also has an ambitious and wide-ranging program of other experiments, which test various aspects of particle and nuclear physics, and develop practical spin-off applications of the cutting-edge technology required to push our understanding of the universe to deeper and deeper levels.

    Having lived there on and off for many years, the question I get asked more than any other is: “What does a person at CERN actually do all day?”

    2
    Martin White – proudly part of “an endless search for the unknown’. Credit: GLENN HUNT

    I never had a typical day at CERN, since my work brought me into contact with computer scientists, civil and electrical engineers, medical physicists, theoretical physicists, accelerator experts, and detector physicists.

    The only common thread was attendance at a large number of meetings which, when located at opposite ends of the main site, led to frantic daily runs of a few kilometres that contributed to a significant weight loss – until I discovered the CERN cake selection.

    The preferred language is English, but it’s not easy to recognise it as such, due to a heavy reliance on jargon and acronyms.

    Moreover, I met physicists who could answer me in English, before translating for an Italian colleague, and mocking my question in German to a bystander.

    Nevertheless, I am always surprised at how quickly the exotic becomes normalised at CERN, whether that means getting acclimatised to constantly being surrounded by extraordinarily smart people or becoming used to dinner party statements like “I have a terrible day tomorrow – I have to reassemble the positron accumulator!”

    My work at CERN has involved the ATLAS experiment, one of the seven experiments of the LHC whose job is to filter and record the results of proton-proton collisions that occur more than one billion times a second.

    The middle of this detector is effectively a giant digital camera, consisting of 6.3 million strips of silicon, and my first job at CERN was to write the software that monitored each of these strips individually to confirm that the system was operating smoothly.

    I am one of CERN’s 12,000 users, and like most of them I have worked for various universities and research institutes scattered around the world, with frequent travel to the CERN laboratory as an external participant.

    The intense lure of CERN is that it remains the best international facility for discovering the new particles and laws of nature that would explain both how the Universe works on its smallest scales, and how it operated 0.0000000001 seconds after the Big Bang.

    The Standard Model of particle physics that I learnt as an undergraduate, and now pass on to my students, remains incapable of explaining most of the matter in the Universe, and it is widely believed that the LHC will finally shift us to a higher plane of understanding.

    LHC

    CERN map


    CERN LHC Maximilien Brice and Julien Marius Ordan


    CERN LHC particles

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS

    CERN ATLAS Image Claudia Marcelloni CERN/ATLAS

    ALICE

    CERN/ALICE Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    See the full article here .


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  • richardmitnick 12:16 pm on December 9, 2019 Permalink | Reply
    Tags: "When storms become stormquakes", , COSMOS, , ,   

    From Scripps Institution of Oceanography via COSMOS: “When storms become stormquakes” 

    From Scripps Institution of Oceanography

    via

    Cosmos Magazine bloc

    COSMOS Magazine

    09 December 2019
    Richard A Lovett

    Geophysicists link wild weather to seismic waves.

    1
    Hurricane Bill, then at Category 4, over the Dominican Republic on 19 August 2009.
    Credit: Jeff Schmaltz, NASA, MODIS Rapid Response Team, Goddard Space Flight Centre.

    NASA Terra MODIS schematic

    NASA Terra satellite

    There is more to hurricanes and typhoons than wind and rain, scientists say. Big enough storms can generate offshore earthquakes large enough to rattle windows if they occurred on land.

    The phenomenon came to light when geophysicist Catherine de Groot-Hedlin, from Scripps Institution of Oceanography, US, and colleagues noticed odd signals in 2009 data from an array of 400 seismometers deployed across the western interior of North America.

    Curious, they traced the signals to their source, and found that the source had been moving northward along the US/Canadian Atlantic seaboard, directly in tandem with one of the year’s strongest storms, Hurricane Bill, which at its peak reached Category 4.

    In a study presented on Saturday at a meeting of the Acoustical Society of America, the team looked back over 10 years of seismic data, hunting for similar traces of what de Groot-Hedlin is now labelling “stormquakes”.

    Hurricane Bill, they found, wasn’t the only source of such tremors: other hurricanes and powerful winter storms known in New England and Canada as Nor’easters had the same effect, producing seabed temblors measuring as large as magnitude 3.5 on the Richter scale.

    But stormquakes didn’t occur for all storms, nor did they occur along the entire storm track of the storms for which they did occur.

    Rather, they appeared to be largely confined to parts of the ocean with wide continental shelves (shallow seabed extending outward from the continent), such as occur in New England, Canada’s Georges Bank, and parts of Florida.

    The best guess for what’s happening, de Groot-Hedlin says, is that alternating giant waves and deep troughs created by the storm are changing water pressure at the seabed by enough to make it vibrate, with a frequency of about one vibration every 20 to 50 seconds.

    “The seismometers are recording that pounding,” she says.

    Stormquakes don’t occur in deep water, however, because there the seabed is more isolated from the beating going on at the surface.

    “Most hurricanes we studied were strong as they passed north along Georgia to New Jersey [where the seabed is deep] but weakened by the time they hit offshore New England,” de Groot-Hedlin says. “Despite this, stormquakes were only detectable off the coast of the New England region and Georges Bank, when the storms were weaker.”

    In theory, stormquakes could be used to help track major storms, but the reality is that there are a lot of simpler ways of doing that.

    Instead, stormquakes might better be used as a way of investigating ocean wave dynamics during large storms.

    In addition, de Groot-Hedlin says, seismic waves are valuable to geophysics seeking methods of probing the Earth’s interior structure. “Now there’s another source [of seismic waves] that could be useful,” she says.

    See the full article here .

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    A department of UC San Diego, Scripps Institution of Oceanography is one of the oldest, largest, and most important centers for ocean, earth and atmospheric science research, education, and public service in the world.

    Research at Scripps encompasses physical, chemical, biological, geological, and geophysical studies of the oceans, Earth, and planets. Scripps undergraduate and graduate programs provide transformative educational and research opportunities in ocean, earth, and atmospheric sciences, as well as degrees in climate science and policy and marine biodiversity and conservation.

     
  • richardmitnick 2:39 pm on December 6, 2019 Permalink | Reply
    Tags: "New clues to the Milky Way’s age", , , , , , , COSMOS   

    From COSMOS Magazine: “New clues to the Milky Way’s age” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    06 December 2019

    Star-quake vibrations suggest ‘thick disc’ is 10 billion years old.

    1
    Infrared cameras reveal the stars of the crowded galactic centre region of the Milky Way.
    Credit: NASA

    2
    Credit: NASA/JPL Caltech/R.Hurt/SSC

    The Milky Way’s “thick disc” is about 10 billion years old, according to an international team of scientists.

    They used data from NASA’s now-defunct Kepler space telescope to study star-quake vibrations – and appear to have cleared up a long-standing mystery.

    “Earlier data about the age distribution of stars in the disc didn’t agree with the models constructed to describe it, but no one knew where the error lay – in the data or the models,” says Sanjib Sharma from Australia’s ARC Centre of Excellence for All Sky Astrophysics in Three Dimensions (ASTRO-3D).

    “Now we’re pretty sure we’ve found it.”

    Sharma is lead author of a paper published in the Monthly Notices of the Royal Astronomical Society. He worked with 37 other researchers from Australia, the US, Germany, Austria, Italy, Denmark, Slovenia and Sweden.

    The Milky Way – like many spiral galaxies – consists of two disc-like structures.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt. The bar is visible in this image

    The thick disc contains only about 20% of the galaxy’s stars and, based on its vertical puffiness and composition, is thought to be the older.

    To find out just how much older, Sharma and colleagues used asteroseismology – a way of identifying the internal structures of stars by measuring their oscillations from star quakes.

    “The frequencies produced tell us things about the stars’ internal properties, including their age,” says ASTRO-3D’s Dennis Stello. “It’s a bit like identifying a violin as a Stradivarius by listening to the sound it makes.”

    The researchers don’t “hear” the sound generated by star-quakes. Instead, they look for how the internal movement is reflected in changes to brightness.

    “Stars are just spherical instruments full of gas,” says Sharma, “but their vibrations are tiny, so we have to look very carefully.

    “The exquisite brightness measurements made by Kepler were ideal for that. The telescope was so sensitive it would have been able to detect the dimming of a car headlight as a flea walked across it.”

    The data delivered by the telescope during the four years after it launched in 2009 presented a problem. It suggested there were more younger stars in the thick disc than models predicted.

    The question confronting astronomers was stark: were the models wrong, or was the data incomplete?

    In 2013, however, Kepler broke down, and NASA reprogrammed it to continue working on a reduced capacity – a period that became known as the K2 mission. The project involved observing many different parts of the sky for 80 days at a time.

    This allowed for a fresh spectroscopic analysis. This revealed that the chemical composition incorporated in the existing models for stars in the thick disc was wrong, which affected the prediction of their ages.

    Taking this into account, the researchers found that the observed asteroseismic data now fell into “excellent agreement” with model predictions.

    See the full article here .


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  • richardmitnick 1:03 pm on October 18, 2019 Permalink | Reply
    Tags: "Galactic cosmic rays could have produced Titan’s sand dunes", COSMOS,   

    From COSMOS Magazine: “Galactic cosmic rays could have produced Titan’s sand dunes” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    18 October 2019
    Richard A Lovett

    1
    The dark grains of sand on Titan are unlike those on Earth. Stocktrek Images

    Sprawling fields of dark-coloured sand dunes on Saturn’s giant moon Titan may have been produced by eons of irradiation by galactic cosmic rays, scientists say.

    The dunes, discovered by NASA’s Cassini spacecraft and the ESA’s Huygens lander, sprawl over 10 million square kilometres of Titan’s surface, an area about the size of the US, including Alaska. They reach heights of nearly 100 metres.

    But their grains are not like Earth’s sands. Most probably they are made of a mix of water ice and complex organics, such polycyclic aromatic hydrocarbons (PAHs), which are composed of multiple carbon rings linked together.

    Historically, scientists have believed that the dunes’ organic compounds were formed by the action of sunlight on methane and nitrogen in Titan’s thick atmosphere, via a photochemical process akin to that which creates smog in polluted cities. Over time, they thought, these smog-like particles gradually settled on Titan’s surface.

    In a paper published the journal Science Advances, however, scientists from the University of Hawaii at Manoa discovered that similar materials could be formed via irradiation from galactic cosmic rays.

    Galactic cosmic rays are an extremely powerful form of radiation that enters our solar system from interstellar space. Earth is largely protected by its magnetic field, says principle investigator Ralf Kaiser from the University of Hawaii at Manoa in Honolulu.

    Titan has no such magnetic shielding, although its dense atmosphere – much denser than Earth’s – does block most of the radiation.

    But if enough gets through that, over time, it has a major effect, Kaiser says.

    In laboratory experiments, his team bombarded acetylene ice – a material known to exist on Titan – with high-energy electrons, which are a good stand-in for actual cosmic rays. They continued until the acetylene had received the equivalent of 100 years worth of space radiation falling on Titan’s surface.

    They then cataloged the reaction products, discovering PAHs with up to three or four rings.

    “This is against conventional wisdom,” Kaiser says, “because scientists think that to form aromatic structures you need high temperatures like combustion.”

    But the energy from the cosmic rays was so intense that these compounds formed at temperatures far below that of Titan’s surface of -179 degrees Celcius.

    The process, he adds, works very quickly, especially compared to geological time scales. “Lots of organic material could accumulate,” he says.

    More importantly, he says, it also works in a vacuum. That means that other acetylene-containing bodies in the outer solar system could also have PAHs, a possible explanation for why some of them have mysterious dark patches of organic compounds on their surfaces.

    Kaiser’s team hasn’t proven that cosmic rays are the only ways by which PAHs can be formed on Titan, says Ralph Lorenz, a planetary scientist at Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, who was not part of the study team. In fact, he says, there is evidence that these chemicals also exist in Titan’s atmosphere.

    “[But] they’ve shown that the chemistry story doesn’t (completely) stop when material settles out of the atmosphere,” he says. “It is interesting that future processing on the surface by the (small) flux of cosmic rays is possible.”

    Happily, Lorenz says, NASA recently green-lighted a return mission to Titan, called Dragonfly, scheduled for launch in 2026. “Dragonfly will initially land among sand dunes,” Lorenz says. “So it should find out.”

    See the full article here .


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  • richardmitnick 10:22 am on October 7, 2019 Permalink | Reply
    Tags: "Gas emissions discovered from interstellar comet", , , , , COSMOS   

    From COSMOS Magazine: “Gas emissions discovered from interstellar comet” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    07 October 2019
    Richard A Lovett

    Astronomers have detected gas emissions from a comet streaking into our Solar System from interstellar space.

    The comet, named 2I/Borisov, was first spotted on 30 August by a Crimean amateur astronomer, and is only the second such interstellar interloper ever to be found.

    1
    An artist’s concept of the interstellar comet named 2I/Borisov. NASA/JPL

    Gas emissions from it are a significant find because they allow scientists to use spectrographic methods to begin deciphering exactly what the comet is made of.

    That wasn’t possible with 1I/’Oumuamua, the only other interstellar object to be caught traversing the Solar System, because ’Oumuamua was never seen to emit detectable amounts of gas.

    “For the first time, we are able to accurately measure what an interstellar visitor is made of and compare it with our own Solar System,” says Alan Fitzsimmons, an astrophysicist at Queens University, Belfast, UK.

    So far, the astronomers have detected only one gas being emitted by the comet, cyanogen (CN). They have also put an upper bound on the amount of another gas, diatomic carbon (C2), which would have been detectable if the comet was producing a lot of it.

    What’s more, they’ve been able to measure the rate at which CN is being emitted into the comet’s tail and coma (the cloud surrounding its nucleus), as well as making estimates about the amount of dust the comet is producing.

    Based on these figures and the normal rates at which comets of various sizes emit such materials, it appears that the comet’s nucleus measures somewhere between 1.4 and 6.6 kilometers in diameter, they say.

    That makes it a lot bigger than ’Oumuamua, which appears to have been a cigar-shaped body with an average diameter of no more than 200 meters.

    ’Oumuamua was so small, in fact, that it was not detected until late in its passage through the Solar System, allowing only a two-week opportunity for detailed observation.

    Borisov, on the other hand, is still on its way into the Solar System and will be visible until October 2020, Fitzsimmons’s team says in their paper, which has been submitted to the journal The Astrophysical Journal Letters.

    But the most interesting thing is how ordinary Borisov appears to be. “If it were not for its interstellar nature, our current data shows that 2I/Borisov would appear as a rather unremarkable comet in terms of activity and coma composition,” Fitzsimmons’ team write.

    So far, only a single gas has been discovered. “But that’s still one step further in understating the composition of the ‘exocomet,’ if you want to call it that,” says Humberto Campins, a planetary scientist from Central Florida University, Orlando, who was not part of Fitzsimmons’ team.

    “And it is headed closer to the Sun, so we should have an opportunity to study it in more detail.”

    See the full article here .


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    Please help promote STEM in your local schools.

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