Tagged: EarthSky Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 10:26 am on December 27, 2018 Permalink | Reply
    Tags: , , , , , EarthSky, , What does Ceres’ carbon mean?   

    From EarthSky and SwRI: “What does Ceres’ carbon mean?” 

    1

    From EarthSky

    December 27, 2018
    Paul Scott Anderson

    Earlier this month, scientists announced that dwarf planet Ceres has more carbon-rich organics than previously thought, both on and below its surface. Here’s why that’s exciting.

    1
    False-color image of dwarf planet Ceres – largest body in the asteroid belt – from the Dawn spacecraft. The image shows Ceres’ famous bright spots, and the false color highlights differences in surface materials. Image via NASA PhotoJournal.

    Carbon is one of the most common elements in the universe and is the basis of organic biology on Earth. It can be found throughout the solar system, even in meteorites that bounce to Earth’s surface from other parts of space. Now scientists have found that another body in the solar system – the dwarf planet Ceres – is much richer in carbon that previously thought. Those results were published in a peer-reviewed article in Nature Astronomy on December 10, 2018.

    Astronomer Simone Marchi at Southwest Research Institute (SwRI) was the lead author of the new paper. He said:

    “Ceres is like a chemical factory. Among inner solar system bodies, Ceres has a unique mineralogy, which appears to contain up to 20 percent carbon by mass in its near surface. Our analysis shows that carbon-rich compounds are intimately mixed with products of rock-water interactions, such as clays.”

    2
    The interior structure of Ceres as scientists now understand it. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

    Why is the presence of carbon so intriguing? Carbon isn’t by itself necessarily the product of or connected to life, although it does serve as the basis for organic chemistry and biology on Earth. When combined with oxygen and hydrogen, carbon can form many groups of important biological compounds including sugars, alcohols and fats. Its presence on Ceres is evidence that the basic ingredients for life – including carbon – can be found in many different places, not only in our solar system but throughout the universe.

    More specifically, the new findings show that Ceres was, and still is, rich in amorphous carbon – a carbon-rich organic material – which is significant in terms of how carbon is distributed throughout the solar system. (Organic materials are any molecules that contain carbon – they can be formed on their own without life but are also building blocks of life). The new data suggests that Ceres contains several times more amorphous carbon on its surface and in its subsurface than even the most carbon-rich meteorites.

    While Ceres contains more carbon than meteorites, the study also shows that 50 to 60 percent of Ceres’ upper crust may have a composition similar to primitive carbonaceous chondrite meteorites – some of the most complex of all meteorites.

    3
    Close-up view inside Urvara crater on Ceres. The 6,500-foot (1981-meter) central ridge is made from materials uplifted from deep below the surface, which experienced rock-water chemical interactions. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

    As Marchi explained:

    “Our results imply that either Ceres accreted ultra-carbon-rich materials or that carbon was concentrated in its crust. Both potential scenarios are important, because Ceres’ mineralogical composition indicates a global-scale event of rock-water alteration, which could provide conditions favorable to organic chemistry.”

    In other words, the carbon on Ceres may originate from when Ceres first formed or from incoming impacts of other asteroids. Scientists don’t know yet which scenario is correct. But regardless, the evidence for chemical reactions with water is intriguing, since that can eventually lead to the formation of the building blocks of life, even if not life itself.

    Ceres is classified as a dwarf planet but is also the largest asteroid in the main asteroid belt between Mars and Jupiter. NASA’s Dawn spacecraft recently finished its mission at Ceres on November 1, 2018, studying its geology and sending back incredible high-resolution images of its surface from orbit.

    NASA Dawn Spacescraft

    One big surprise was the “bright spots” – light-colored deposits, now determined to be sodium carbonate salts – on the darker rocky surface. Scientists think they were formed when when water came up to the surface from deeper below and then evaporated in Ceres’ extremely tenuous and sporadic water vapor “atmosphere.”

    The best-known bright spots are those in Occator Crater, which stand out starkly against the darker rocky surface.

    4
    High-resolution view of Cerealia Facula – a sodium carbonate (salt) deposit – in Occator Crater. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/Roman Tkachenko.

    Whether Ceres ever had conditions suitable for life to evolve is still unknown, although there is also evidence that it has, or at least once had, water below the surface – maybe even a subsurface ocean. This water produced chemical reactions when it came in contact with minerals in rocks. There is also evidence for past cryovolcanic activity – cryovolcanoes, which erupt water, ammonia or methane rather than molten rock. It’s even possible that the subsurface environment was once warm and wet enough for basic biological chemistry to actually begin, although no direct signs of that have been discovered yet.

    Bottom line: As the largest object in the asteroid belt, Ceres is a fascinating world, and has been more geologically active than previously thought. The fact that Ceres is rich in organic carbon is a big part of its geological history and now scientists are beginning to understand what that means not only for the widespread presence of carbon in the solar system but also how organic chemistry can – at least sometimes – lead to the development of life itself.

    See the full EarthSky article here .

    From SwRI: “SwRI-led team finds evidence for carbon-rich surface on Ceres”

    December 10, 2018

    A team led by Southwest Research Institute has concluded that the surface of dwarf planet Ceres is rich in organic matter. Data from NASA’s Dawn spacecraft indicate that Ceres’ surface may contain several times the concentration of carbon than is present in the most carbon-rich, primitive meteorites found on Earth.

    “Ceres is like a chemical factory,” said SwRI’s Dr. Simone Marchi, a principal scientist who was the lead author of research published in Nature Astronomy today. “Among inner solar system bodies, Ceres has a unique mineralogy, which appears to contain up to 20 percent carbon by mass in its near surface. Our analysis shows that carbon-rich compounds are intimately mixed with products of rock-water interactions, such as clays.”

    Ceres is believed to have originated about 4.6 billion years ago at the dawn of our solar system. Dawn data previously revealed the presence of water and other volatiles, such as ammonium derived from ammonia, and now a high concentration of carbon. This chemistry suggests Ceres formed in a cold environment, perhaps outside the orbit of Jupiter. An ensuing shakeup in the orbits of the large planets would have pushed Ceres to its current location in the main asteroid belt, between the orbits of Mars and Jupiter.

    “With these findings, Ceres has gained a pivotal role in assessing the origin, evolution and distribution of organic species across the inner solar system,” Marchi said. “One has to wonder about how this world may have driven organic chemistry pathways, and how these processes may have affected the make-up of larger planets like the Earth.”

    Geophysical, compositional and collisional models based on Dawn data revealed that Ceres’ partially differentiated interior has been altered by fluid processes. Dawn’s Visible and Infrared Mapping Spectrometer has shown that the overall low albedo of Ceres’ surface is a combination of rock-water interaction products such as phyllosilicates and carbonates and a significant amount of spectrally neutral darkening agents, such as an iron oxide called magnetite.

    Because Dawn’s Gamma Ray and Neutron Detector limits magnetite to only a few percent by mass, the data point to the presence of an additional darkening agent, probably amorphous carbon, a carbon-rich organic material. Interestingly, specific organic compounds have also been detected near a 31-mile-wide impact crater named Ernutet, giving further support to the widespread presence of organics in Ceres’ shallow subsurface.

    The new study also finds that 50-60 percent of Ceres’ upper crust may have a composition similar to primitive carbonaceous chondrite meteorites. This material is compatible with contamination from infalling carbonaceous asteroids, a possibility supported by Ceres’ battered surface.

    “Our results imply that either Ceres accreted ultra-carbon-rich materials or that carbon was concentrated in its crust,” Marchi said. “Both potential scenarios are important, because Ceres’ mineralogical composition indicates a global-scale event of rock-water alteration, which could provide conditions favorable to organic chemistry.”

    The paper “An aqueously altered carbon-rich Ceres” was published on December 10 in Nature Astronomy. The Dawn mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. JPL is responsible for overall Dawn mission science. Northrop Grumman in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.

    For more information visit Planetary Science or contact Deb Schmid, (210) 522-2254, Communications Department, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510.

    See the full SwRI article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.orgin 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

    Advertisements
     
    • stewarthoughblog 10:35 pm on December 27, 2018 Permalink | Reply

      Some very interesting science here, but “but also how organic chemistry can – at least sometimes – lead to the development of life itself.” is faith based speculation, not objective science. There is no viable evidence that organic chemistry ever formed sufficiently to posit that any serious biochemical compounds ever formed anything remotely complex that could be considered anything relevant to anything living.

      Like

  • richardmitnick 10:45 am on December 9, 2018 Permalink | Reply
    Tags: A comet-like tail made up of helium particles escaping the planet’s atmosphere due to pressure from ultraviolet radiation from this world’s star, , , , , EarthSky, , WASP-69b the exoplanet with a tail   

    From Instituto de Astrofísica de Canarias – IAC via EarthSky: “WASP-69b, the exoplanet with a tail” 

    IAC

    From Instituto de Astrofísica de Canarias – IAC

    via

    1

    EarthSky

    December 9, 2018
    Paul Scott Anderson

    Astronomers have discovered a Jupiter-sized planet – 163 light-years away – that seems to think it’s a comet. It has a prominent “tail” of helium gas.

    1
    Artist’s concept of exoplanet WASP-69b, thought to orbit its sun with a comet-like helium tail trailing behind. Image via Gabriel Perez Diaz/IAC.

    Planets and comets are two quite different things. Planets are massive enough to have strong-enough self-gravity to have pulled themselves into the shape of round balls. The cores of comets are tiny in comparison; they are small chunks irregular of rock and ice, whose characteristic long “tails” of gas and dust only appear as they swing in near the sun. Planets don’t typically have tails as comets do … except that now astronomers have found one that does. Scientists at the Instituto de Astrofísica de Canarias (IAC) in the Canary Islands have shown that the giant exoplanet WASP-69b has a comet-like tail made up of helium particles. The new results were published on December 6, 2018 in the peer-reviewed journal Science.

    The helium particles in the tail of WASP-69b are escaping the planet’s atmosphere due to pressure from ultraviolet radiation from this world’s star. The tail trails behind the planet as it orbits its star. WASP-69b is a gas giant planet 163 light-years from our sun. It is about the size of Jupiter, but with a similar mass to Saturn.

    How did astronomers make this discovery? When they observed the planet transit in front of its star, they noticed something interesting.

    Planet transit. NASA/Ames

    As explained by Lisa Nortmann of IAC, lead author of the new paper:

    “We observed a stronger and longer-lasting dimming of the starlight in a region of the spectrum where helium gas absorbs light. The longer duration of this absorption allows us to infer the presence of a tail.

    This is the first time we can actually observe a helium tail. Before, it was assumed that if helium is in the [outermost atmospheric layer of a] planet, it might escape and form a tail.

    That was based on models, but this is the first time we can actually observe it while it’s still in front of the star, when the planet is not in front of the star anymore.”

    2
    Comets – as in this view of comet 45P/Honda-Mrkos-Pajdušáková, which zipped past Earth in 2017 – are famous for their beautiful long tails. The tails can be millions of miles long. They are made of dust and gases. Image via Gerald Rhemann/NASA.

    The observations were made using the CARMENES instrument – a spectrograph – on the 3.5-meter telescope of the Calar Alto Observatory in Almería, Spain. The spectrograph simultaneously covered both the visible wavelength range and the near infrared range at high spectral resolution. THerefore it revealed the composition of the atmosphere of the planet, and the astronomers were able to determine the speed of the helium particles that leave the gravitational field of the planet and the length of the tail they produce.

    CARMENES spectrograph, mounted on the Calar Alto 3.5 meter Telescope, located in Almería province in Spain on Calar Alto, a 2,168-meter-high (7,113 ft) mountain in Sierra de Los Filabres


    Calar Alto 3.5 meter Telescope, located in Almería province in Spain on Calar Alto, a 2,168-meter-high (7,113 ft) mountain in Sierra de Los Filabres

    How cool is that? Apparently even planets can sport tails, if conditions are just right.

    The new paper also announces some additional results in addition to the planetary tail. Four other exoplanets were also studied in the same way – hot Jupiter exoplanets HD 189733b and HD 209458b, the extremely hot giant planet KELT-9b and the warm Neptune-sized exoplanet Gliese 436b. Surprisingly, the last three of those planets also have helium exospheres, which is unexpected. HD 189733b is absorbing helium, but the helium envelope around the planet is more compact and does not form a tail in this case.

    All five planets were also observed using the European Space Agency’s Multi-Mirror X-Ray Mission (XMM-Newton).

    ESA/XMM Newton

    Helium was found in the atmosphere of the planets that receive the most X-ray and extreme ultraviolet radiation from their host stars. As Enric Pallé, IAC researcher and paper co-author, said:

    “This is a first big step toward finding out how exoplanet atmospheres evolve over time and what the distribution of masses and radii of the observed population of super-Earth and mini-Neptune planets could result from.”

    3
    In 2011, the Neptune-sized exoplanet Gliese 436b had also been found to have a tail – shown in this artist’s concept – composed of hydrogen. Image via NASA/ESA/STScI/G. Bacon.

    These additional observations are useful for how showing how extreme radiation from a star can strip away the thick atmospheres of giant planets, leaving behind their smaller rocky cores – those planets could then resemble Earth or Venus. According to Michael Salz, a researcher at the University of Hamburg and first author of a companion publication by the same research team:

    “In the past, studies of atmospheric escape, like the one we have seen in WASP-69b, were based on space-borne observations of hydrogen in the far ultraviolet, a spectral region of very limited access and strongly affected by interstellar absorption. Our results show that helium is a very promising new tracer to study atmospheric escape in exoplanets.”

    WASP69b isn’t the first exoplanet to be found with a tail. In 2014, astronomers discovered that Gliese 436b – about the size and mass of Neptune and 30 light-years away – appeared to also have a comet-like tail, but composed of hydrogen instead of helium. While such planetary tails may not be all that common, that discovery – and now the new one – shows that they can occur.

    Bottom line: Comets are famous for their beautiful, long, glowing tails. New research confirms that even planets – like WASP-69b – can sometimes have tails, too.

    See the full article here.


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teaching and outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.



    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC

     
  • richardmitnick 11:03 am on November 28, 2018 Permalink | Reply
    Tags: A billionaire’s plan to search for life on Enceladus, , , , , Breakthrough Starshot Foundation, , EarthSky, ,   

    From EarthSky: “A billionaire’s plan to search for life on Enceladus” 

    1

    From EarthSky

    November 27, 2018
    Paul Scott Anderson

    Russian entrepreneur and physicist Yuri Milner wants to send a probe back to Saturn’s ocean moon Enceladus, to search for evidence of life there. NASA wants to help him.

    1
    Illustration showing plumes on Saturnian moon Enceladus. Illustration: NASA /JPL-Caltech

    Saturn’s moon Enceladus is very small – only about 310 miles (500 kilometers) across – but it may hold clues to one of the biggest mysteries of all time – are we alone? Beneath the icy crust lies a global salty ocean, not too different from Earth’s oceans. Could that ocean contain life of some kind? That is a question that many scientists – and the public alike – would like to find an answer for. Enceladus, however, is very far away and planetary missions are expensive – but there may be an ideal solution.

    Billionaire entrepreneur and physicist Yuri Milner wants to send a private mission back to this intriguing world, and NASA wants to help him. This incredible idea was first reported in New Scientist on November 8, 2018 (please note this article is behind a paywall). It was then reported by Gizmodo the same day.

    “It looks like NASA will offer billionaire entrepreneur and physicist Yuri Milner help on the first private deep-space mission: a journey designed to detect life, if it exists, on Saturn’s moon Enceladus, according to documents acquired by New Scientist.

    New Scientist’s Mark Harris reports:

    Agreements signed by NASA and Milner’s non-profit Breakthrough Starshot Foundation in September show that the organisations are working on scientific, technical and financial plans for the ambitious mission. NASA has committed over $70,000 to help produce a concept study for a flyby mission. The funds won’t be paid to Breakthrough but represent the agency’s own staffing costs on the project.

    The teams will be working in the project plan and concepts through next year, New Scientist reports.”

    3
    Enceladus is a very small moon, but it has a global ocean beneath its icy crust. Image via NASA/JPL-Caltech.

    Breakthrough Initiatives, part of Milner’s non-profit Breakthrough Starshot Foundation, would lead and pay for the mission, with consultation from NASA. The board of Breakthrough Initiatives includes billionaires Yuri Milner and Mark Zuckerberg, and the late physicist Stephen Hawking. Breakthrough Initiatives has been studying various mission concepts for space exploration, including a solar sail to nearby stars, advancing the technology to discover other Earth-like planets and sending out a direct message, similar to the previous Arecibo message, specifically to try and catch the attention of aliens.

    Solar sail. Breakthrough Starshot image. Credit: Breakthrough Starshot

    This radio message was transmitted toward the globular cluster M13 using the Arecibo telescope in 1974. Image Credit Arne Nordmann (norro) Wikipedia


    NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft).

    Enceladus has become a prime target in the search for extraterrestrial life in our solar system, since its subsurface ocean is thought to be quite similar to oceans on Earth, thanks to data from the Cassini mission, which orbited Saturn from 2004 until September of last year.

    NASA/ESA/ASI Cassini-Huygens Spacecraft

    Scientists already know it is salty and there is evidence for geothermal activity on the ocean floor, such as “smoker” volcanic vents on the bottom of oceans on Earth. Such geothermal vents – at least on Earth – are oases for a wide variety of ocean life despite the darkness and cold temperatures away from the vents.

    Cassini also investigated the plumes of Enceladus – huge “geysers” of water vapor erupting through cracks in the surface at the south pole of Enceladus. Cassini flew right through some of them, analyzing their composition, and found they contain water vapor, ice particles, complex organic molecules and salts. Cassini wasn’t capable of finding life directly, but it did find valuable clues and hints that there may well be something alive in that alien ocean, even if only microbes.

    Earlier this year, New Scientist also reported that there may already be some tentative evidence for microbes in Enceladus’s ocean [Nature Communications]. Cassini detected traces of methane in the water vapor plumes, and when scientists tested computer models of conditions in the ocean, they found that microbes that emit methane after combining hydrogen and carbon dioxide – called methanogens – could easily survive there. According to Chris McKay at NASA’s Ames Research Center in Moffett Field, California:

    “This [team] has taken the first step to showing experimentally that methanogens can indeed live in the conditions expected on Enceladus.”

    The scientists found that the microbes were able to thrive at temperatures and pressures likely found in Enceladus’s oceans, ranging from 0 to 90 degrees Celsius, and up to 50 Earth atmospheres. They also found that olivine minerals, thought to exist in the moon’s core, could be chemically broken down to produce enough hydrogen for methanogens to thrive.

    4
    Another proposed return mission to Enceladus is the Enceladus Life Finder (ELF), which would orbit Saturn and make repeated passes through the plumes – like Cassini, but with updated instruments. Image via Jonathan Lunine.

    Another proposed return mission to Enceladus is the Enceladus Life Finder (ELF), which would orbit Saturn and make repeated passes through the plumes – like Cassini, but with updated instruments that could even test whether any amino acids found have predominately left or right-handed structures. (Life on Earth predominately creates left-handed forms, and scientists think that life elsewhere will also favor one form over the other instead of a random mixture as would occur from abiotic chemistry.)

    Cassini wasn’t designed to detect life directly, but on a future mission – such as the one proposed – a mass spectrometer would be able to detect carbon isotope ratios unique to living organisms, as well as other potential “biomarkers” of methanogens, including lipids and hydrocarbons.

    Bottom line: Scientists are eager to return to Enceladus to learn more about its intriguing subsurface ocean. The new plan by billionaire Yuri Milner, with NASA’s assistance, may be the best bet to go back and see if anything is swimming in those mysterious alien waters.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.orgin 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
    • stewarthoughblog 10:52 pm on November 28, 2018 Permalink | Reply

      This substantiates the maxim that intelligence can only be coincidently related to financial possession. Even considering that science can be expected to pursue the investigation of a wide array of physical phenomenon, wasting $billions on speculation of the possibility of life on remote bodies is nonsensical considering that there is virtually a total absence of any evidence of naturalist creation of life on Earth. Projection of any conditions on Enceladus of conditions similar to primordial Earth is pure faith, not based on scientific evidence.

      But, it is true that anyone can spend their money (peaceably) on what they want to

      Like

      • richardmitnick 2:08 pm on November 29, 2018 Permalink | Reply

        I totally agree with your assessment of this proposed project. But, of course, it is Milner’s money. The real problem beyond is that we cannot squelch even the wildest quests in hopes for new science. Science never sleeps. The best example of this is that when our Congress in 1993 killed the Superconducting super collider, we left the door wide open for Europe via CERN to build its substitute, the LHC and High Energy Physics simply moved to Europe.

        Like

  • richardmitnick 8:51 am on November 12, 2018 Permalink | Reply
    Tags: , , ASU geoscientists discover an overlooked source for Earth's water, , , , , EarthSky   

    From Arizona State University via EarthSky: “ASU geoscientists discover an overlooked source for Earth’s water” 

    ASU Bloc

    From Arizona State University

    via

    EarthSky

    November 12, 2018
    Paul Scott Anderson

    For decades, scientists have said that at least some of Earth’s water came from comets and asteroids. New research suggests an even more primordial source, the vast cloud in space from which our world formed.

    1
    Earth, the water planet. Image via NASA.

    Earth is rich in water, and has been for a few billion years, but scientists are still debating just where all that life-sustaining liquid came from. At least some of it was thought to have been brought here by comets or asteroids, but that idea still falls short in explaining how so much water ended up on Earth’s surface – and deep below, as well. Now, a team of scientists at Arizona State University (ASU), led by Peter Buseck, has come up with a new proposal. The new peer-reviewed paper was published in the Journal of Geophysical Research: Planets on October 9, 2018.

    The new research suggests that Earth’s water came from both rocky material, such as asteroids, and from the vast cloud of dust and gas remaining after the sun’s formation, called the solar nebula.

    Earth’s ocean water is similar to that found in asteroids. That’s one reason scientists have long thought that most earthly water came from an asteroid bombardment in the days of the early solar system. The ratio of deuterium – a heavier hydrogen isotope – to normal hydrogen is a unique chemical signature in various water sources. In the case of Earth’s oceans, the deuterium-to-hydrogen ratio is close to what is found in asteroids. But, according to Steven Desch, also at ASU and one of the team members:

    “It’s a bit of a blind spot in the community. When people measure the [deuterium-to-hydrogen] ratio in ocean water and they see that it is pretty close to what we see in asteroids, it was always easy to believe it all came from asteroids.”

    2
    How Earth accumuated water, Step 1: Dust and gas collect into embryo bodies with a water content similar to asteroids today. Image by J. Wu, S Desch/ASU

    3
    Step 2: Embryos heat up, develop cores and mantles; most of the hydrogen lies in the cores, with the mantles being richer in deuterium (D). Image by J. Wu, S Desch/ASU

    4
    Step 3: The largest embryo develops a molten magma ocean on its surface from impacts and radioactive decay; iron in the molten layer grabs some hydrogen from the embryo’s primitive hydrogen-rich atmosphere. Image by J. Wu, S Desch/ASU

    5
    Step 4: The magma ocean sinks to just above the embryo’s core, carrying its low D/H material down, where it gradually mixes into the mantle. Image by J. Wu, S Desch/ASU

    6
    Step 5: Embryos of varying sizes and D/H ratios collide, merge and mix, producing an Earth with a mantle rich in hydrogen, as a proxy for water. Image by J. Wu, S Desch/ASU

    7
    Step 6: As Earth continues to evolve, plumes of molten rock rise from the mantle, triggering volcanic activity at the surface — and bringing up rock with a lower D/H ratio than surface rocks have. The result is an Earth with multiple oceans’ worth of hydrogen stored at different depths. Image by J. Wu, S Desch/ASU

    Jun Wu at ASU is lead author of the study. He added:

    “The solar nebula has been given the least attention among existing theories, although it was the predominant reservoir of hydrogen in our early solar system.”

    The hydrogen in Earth’s oceans may not represent the hydrogen throughout the planet as a whole, however. Samples of hydrogen from deep inside the Earth, close to the boundary between the core and mantle, have notably less deuterium – indicating that this hydrogen may not have come from asteroids, after all. The noble gases helium and neon, with isotopic signatures inherited from the solar nebula, have also been found in the Earth’s mantle.

    How to explain these differences? The researchers needed to develop a new theoretical model of Earth’s formation to answer that question. According to the model, Earth was the largest of many planetary embryos – aka protoplanets – in the early solar system.

    Essentially, their model shows large, waterlogged asteroids eventually forming into planets like Earth through collisions.

    The surface of the very young Earth was initially an ocean of magma. Hydrogen and noble gases from the solar nebula were drawn to the planetary embryo, forming the first atmosphere. Nebular hydrogen, which contains less deuterium and is lighter than asteroidal hydrogen, dissolved into the molten iron of the magma ocean.

    Hydrogen was then drawn toward the center of the Earth – a process called isotopic fractionation. Hydrogen was delivered to the core through its attraction to iron, while much of the heavier isotope, deuterium, remained in the magma which eventually cooled to form the mantle. Impacts from smaller planetary embryos and other objects continued to add additional water and mass until Earth reached its final size.

    The end result was that Earth had noble gases deep in its interior, with a lower deuterium-to-hydrogen ratio in its core than in its mantle and oceans. Most of Earth’s water did come from asteroids, but some also came from the solar nebula. As Wu noted:

    “For every 100 molecules of Earth’s water, there are one or two coming from the solar nebula.”

    So what about comets, since they have so much water-ice in them? According to Desch:

    “Comets contain a lot of ices, and in theory could have supplied some water. But there’s another way to think about sources of water in the solar system’s formative days. Because water is hydrogen plus oxygen, and oxygen is abundant, any source of hydrogen could have served as the origin of Earth’s water.”

    Also, comets have higher deuterium-to-hydrogen (D/H) ratios, so they are actually not good sources for Earth’s water. The D/H ratio of hydrogen gas in the solar nebula was only 21 ppm, too low to have supplied most of the water on Earth. Asteroids are a much better match, along with the solar nebula.

    8
    The new study results could also have implications for rocky exoplanets orbiting other stars, such as the super-Earth Wolf 1061c in this artist’s concept image. Many of them could have abundant water, just like Earth. Image via NASA/Ames/JPL-Caltech.

    Finally, the new results have implications for rocky exoplanets orbiting other stars. Many such worlds have now been discovered, and if there is a greater chance for some of them to also have liquid water, that also increases the chances of those planets being habitable. According to the researchers:

    “Our results suggest that forming water is likely inevitable on sufficiently large rocky planets in extrasolar systems.”

    Bottom line: The origin of Earth’s water has been debated for a long time, but this new study points to a source – the solar nebula, or cloud of gas and dust left after the sun’s formation – that had been previously mostly overlooked. The new work, based on computer modeling, may have implications for rocky worlds orbiting distant stars.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    ASU is the largest public university by enrollment in the United States. Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College. A 1958 statewide ballot measure gave the university its present name.
    ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.

    ASU awards bachelor’s, master’s and doctoral degrees in 16 colleges and schools on five locations: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus and the Colleges at Lake Havasu City. ASU’s “Online campus” offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates, earning ASU a Top 10 rating for Best Online Programs. ASU also offers international academic program partnerships in Mexico, Europe and China. ASU is accredited as a single institution by The Higher Learning Commission.

    ASU Tempe Campus
    ASU Tempe Campus

     
  • richardmitnick 9:59 am on October 27, 2018 Permalink | Reply
    Tags: , , EarthSky, , How Earth feeds volcanic supereruptions, Taupo Volcanic Zone of New Zealand,   

    From Vanderbilt University via EarthSky: “How Earth feeds volcanic supereruptions” 

    Vanderbilt U Bloc

    From Vanderbilt University

    via

    EarthSky

    October 21, 2018

    To better understand where magma gathers in Earth’s crust, researchers studied the Taupo Volcanic Zone of New Zealand, the planet’s most active cluster.

    To figure out where magma gathers in the earth’s crust and for how long, volcanologist Guilherme Gualda and his students traveled to the planet’s most active cluster, the Taupo Volcanic Zone of New Zealand, where some of the biggest eruptions of the last 2 million years occurred — seven in a period between 350,000 and 240,000 years ago.

    1
    Mount Ngauruhoe is the tallest peak of the Tongariro complex in the North Island of New Zealand. Photo by Don Swanson, 1984 (U.S. Geological Survey).

    2
    Lake Taupo in New Zealand’s North Island. NASA

    3
    Bay of Plenty, North Island, New Zealand, from the Bay of Plenty coast to Mounts Tongariro, Ngauruhoe, and Ruapehu (at bottom of picture). Also shows Lake Taupo and the Rotorua Lakes. This scene was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA’s , on October 23, 2002. Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC

    NASA Terra satellite

    NASA Terra MODIS schematic

    The aim of the project was to better understand how the systems of magma – molten or semi-molten rock -that feed them are built and how the Earth reacts to repeated input of magma over short periods of time.

    After studying layers of pumice visible in road cuts and other outcrops, measuring the amount of crystals in the samples and using thermodynamic models, they determined that magma moved closer to the surface with each successive eruption.

    Gualda is associate professor of earth and environmental sciences at Vanderbilt University and first author of the study published October 10, 2018, in the peer-reviewed journal Science Advances. He said in a statement:

    “As the system resets, the deposits become shallower. The crust is getting warmer and weaker, so magma can lodge itself at shallower levels.”

    What’s more, the study suggests, the dynamic nature of the Taupo Volcanic Zone’s crust made it more likely for the magma to erupt than to be stored in the crust. The more frequent, smaller eruptions, which each produced 12-36 cubic miles (50-150 cubic km) of magma, likely prevented a supereruption. Supereruptions produce more than 108 cubic miles (450 cubic km) of magma, and they affect the earth’s climate for years following the eruption. Gualda said:

    “You have magma sitting there that’s crystal-poor, melt-rich for few decades, maybe 100 years, and then it erupts. Then another magma body is established, but we don’t know how gradually that body assembles. It’s a period in which you’re increasing the amount of melt in the crust.”

    The question that remains is how long it took for these crystal-rich magma bodies to assemble between eruptions. It could be thousands of years, Gualda said, but he believes it’s shorter than that.

    Bottom line: To figure out where magma gathers in Earth’s crust and for how long, researchers traveled to the planet’s most active cluster: the Taupo Volcanic Zone of New Zealand, site of some of the biggest eruptions of the last 2 million years.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Commodore Cornelius Vanderbilt was in his 79th year when he decided to make the gift that founded Vanderbilt University in the spring of 1873.

    The $1 million that he gave to endow and build the university was the commodore’s only major philanthropy. Methodist Bishop Holland N. McTyeire of Nashville, husband of Amelia Townsend who was a cousin of the commodore’s young second wife Frank Crawford, went to New York for medical treatment early in 1873 and spent time recovering in the Vanderbilt mansion. He won the commodore’s admiration and support for the project of building a university in the South that would “contribute to strengthening the ties which should exist between all sections of our common country.”

    McTyeire chose the site for the campus, supervised the construction of buildings and personally planted many of the trees that today make Vanderbilt a national arboretum. At the outset, the university consisted of one Main Building (now Kirkland Hall), an astronomical observatory and houses for professors. Landon C. Garland was Vanderbilt’s first chancellor, serving from 1875 to 1893. He advised McTyeire in selecting the faculty, arranged the curriculum and set the policies of the university.

    For the first 40 years of its existence, Vanderbilt was under the auspices of the Methodist Episcopal Church, South. The Vanderbilt Board of Trust severed its ties with the church in June 1914 as a result of a dispute with the bishops over who would appoint university trustees.

    kirkland hallFrom the outset, Vanderbilt met two definitions of a university: It offered work in the liberal arts and sciences beyond the baccalaureate degree and it embraced several professional schools in addition to its college. James H. Kirkland, the longest serving chancellor in university history (1893-1937), followed Chancellor Garland. He guided Vanderbilt to rebuild after a fire in 1905 that consumed the main building, which was renamed in Kirkland’s honor, and all its contents. He also navigated the university through the separation from the Methodist Church. Notable advances in graduate studies were made under the third chancellor, Oliver Cromwell Carmichael (1937-46). He also created the Joint University Library, brought about by a coalition of Vanderbilt, Peabody College and Scarritt College.

    Remarkable continuity has characterized the government of Vanderbilt. The original charter, issued in 1872, was amended in 1873 to make the legal name of the corporation “The Vanderbilt University.” The charter has not been altered since.

    The university is self-governing under a Board of Trust that, since the beginning, has elected its own members and officers. The university’s general government is vested in the Board of Trust. The immediate government of the university is committed to the chancellor, who is elected by the Board of Trust.

    The original Vanderbilt campus consisted of 75 acres. By 1960, the campus had spread to about 260 acres of land. When George Peabody College for Teachers merged with Vanderbilt in 1979, about 53 acres were added.

    wyatt centerVanderbilt’s student enrollment tended to double itself each 25 years during the first century of the university’s history: 307 in the fall of 1875; 754 in 1900; 1,377 in 1925; 3,529 in 1950; 7,034 in 1975. In the fall of 1999 the enrollment was 10,127.

    In the planning of Vanderbilt, the assumption seemed to be that it would be an all-male institution. Yet the board never enacted rules prohibiting women. At least one woman attended Vanderbilt classes every year from 1875 on. Most came to classes by courtesy of professors or as special or irregular (non-degree) students. From 1892 to 1901 women at Vanderbilt gained full legal equality except in one respect — access to dorms. In 1894 the faculty and board allowed women to compete for academic prizes. By 1897, four or five women entered with each freshman class. By 1913 the student body contained 78 women, or just more than 20 percent of the academic enrollment.

    National recognition of the university’s status came in 1949 with election of Vanderbilt to membership in the select Association of American Universities. In the 1950s Vanderbilt began to outgrow its provincial roots and to measure its achievements by national standards under the leadership of Chancellor Harvie Branscomb. By its 90th anniversary in 1963, Vanderbilt for the first time ranked in the top 20 private universities in the United States.

    Vanderbilt continued to excel in research, and the number of university buildings more than doubled under the leadership of Chancellors Alexander Heard (1963-1982) and Joe B. Wyatt (1982-2000), only the fifth and sixth chancellors in Vanderbilt’s long and distinguished history. Heard added three schools (Blair, the Owen Graduate School of Management and Peabody College) to the seven already existing and constructed three dozen buildings. During Wyatt’s tenure, Vanderbilt acquired or built one-third of the campus buildings and made great strides in diversity, volunteerism and technology.

    The university grew and changed significantly under its seventh chancellor, Gordon Gee, who served from 2000 to 2007. Vanderbilt led the country in the rate of growth for academic research funding, which increased to more than $450 million and became one of the most selective undergraduate institutions in the country.

    On March 1, 2008, Nicholas S. Zeppos was named Vanderbilt’s eighth chancellor after serving as interim chancellor beginning Aug. 1, 2007. Prior to that, he spent 2002-2008 as Vanderbilt’s provost, overseeing undergraduate, graduate and professional education programs as well as development, alumni relations and research efforts in liberal arts and sciences, engineering, music, education, business, law and divinity. He first came to Vanderbilt in 1987 as an assistant professor in the law school. In his first five years, Zeppos led the university through the most challenging economic times since the Great Depression, while continuing to attract the best students and faculty from across the country and around the world. Vanderbilt got through the economic crisis notably less scathed than many of its peers and began and remained committed to its much-praised enhanced financial aid policy for all undergraduates during the same timespan. The Martha Rivers Ingram Commons for first-year students opened in 2008 and College Halls, the next phase in the residential education system at Vanderbilt, is on track to open in the fall of 2014. During Zeppos’ first five years, Vanderbilt has drawn robust support from federal funding agencies, and the Medical Center entered into agreements with regional hospitals and health care systems in middle and east Tennessee that will bring Vanderbilt care to patients across the state.

    studentsToday, Vanderbilt University is a private research university of about 6,500 undergraduates and 5,300 graduate and professional students. The university comprises 10 schools, a public policy center and The Freedom Forum First Amendment Center. Vanderbilt offers undergraduate programs in the liberal arts and sciences, engineering, music, education and human development as well as a full range of graduate and professional degrees. The university is consistently ranked as one of the nation’s top 20 universities by publications such as U.S. News & World Report, with several programs and disciplines ranking in the top 10.

    Cutting-edge research and liberal arts, combined with strong ties to a distinguished medical center, creates an invigorating atmosphere where students tailor their education to meet their goals and researchers collaborate to solve complex questions affecting our health, culture and society.

    Vanderbilt, an independent, privately supported university, and the separate, non-profit Vanderbilt University Medical Center share a respected name and enjoy close collaboration through education and research. Together, the number of people employed by these two organizations exceeds that of the largest private employer in the Middle Tennessee region.
    Related links

     
  • richardmitnick 1:12 pm on October 25, 2018 Permalink | Reply
    Tags: , , EarthSky, , ,   

    From EarthSky: “Eruption of the world’s deepest undersea volcano” 

    1

    From EarthSky

    October 25, 2018
    Eleanor Imster

    A research team has documented a volcanic eruption in the western Pacific Ocean that’s deeper below the ocean surface than Mount Rainier’s height above sea level.

    1
    Researchers used remotely operated vehicles to explore the deep waters of the Mariana Trench. Image via Oregon State University.

    A team of researchers has documented a recent volcanic eruption in the western Pacific Ocean about 2.8 miles (4.5 km) below the ocean surface that they describe as the deepest known eruption on Earth – deeper below the ocean surface than Mount Rainier’s height above sea level.

    The researchers say the eruption probably happened between 2013-2015 on the Mariana back-arc, a zone of the sea floor with active volcanoes in the Pacific Ocean’s Mariana Trench. The Mariana Trench is the deepest part of the earth’s oceans, and the deepest location of the earth itself. It’s located just east of the 14 Mariana Islands near Japan. It was created by ocean-to-ocean subduction, a phenomenon in which a tectonic plate topped by oceanic crust is subducted beneath another plate also topped by oceanic crust.

    2
    Location of the Mariana Trench. Image via Wikipedia.

    Bill Chadwick is a marine geologist at Oregon State University and lead author on the study, published October 23, 2018 in the peer-reviewed journal Frontiers in Earth Science. Chadwick said in a statement:

    “We know that most of the world’s volcanic activity actually takes place in the ocean, but most of it goes undetected and unseen. That is because undersea quakes associated with volcanism are usually small, and most of the instrumentation is far away on land.

    Many of these areas are deep and don’t leave any clues on the surface. That makes submarine eruptions very elusive.”

    The Mariana back-arc eruption was first discovered in December 2015 by cameras aboard an autonomous underwater vehicle. Photos revealed the presence of a pristine dark, glassy lava flow on the seafloor with no sediment cover. Venting of milky hydrothermal vent fluid indicated that the lava flow was still warm, and therefore very young.

    4
    Fresh lava from the sea floor. Image via Oregon State University.

    Data indicated that there had been major depth changes in the area between surveys in 2013 and 2015, the researchers said, which is consistent with an eruption. The new lava flows stretched over an area about 4.5 miles (7.2 km) long and ranged in thickness between 130-450 feet (40-137 meters).

    The scientists returned in April and December of 2016 and used two remotely operated vehicles to explore the site. The new observations showed a rapidly declining hydrothermal system on the lava flows, suggesting the eruption had taken place only months before its discovery the previous year. Chadwick said:

    “Typically after an eruption, there is heat released and venting for a few years and organisms will colonize the vents, creating a new ecosystem. But after a while, the system cools down and the mobile organisms will leave. There was still some venting, but it had obviously greatly declined.”

    Bottom line: An undersea volcanic eruption discovered in the Pacific Ocean’s Mariana Trench is the deepest known.

    Source: A Recent Volcanic Eruption Discovered on the Central Mariana Back-Arc Spreading Center

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.orgin 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 9:37 am on October 24, 2018 Permalink | Reply
    Tags: , , EarthSky,   

    From EarthSky: “US tornado frequency shifting eastward” 

    1

    From EarthSky

    October 24, 2018
    Eleanor Imster

    Although Tornado Alley is still tops, vulnerable regions east of the Great Plains are catching up, according to a new study.

    1
    Image via Victor Gensini.

    A new study suggests that over the past four decades, tornado frequency has increased over a large swath of the U.S. Midwest and Southeast. The researchers also found that meanwhile, tornado activity has decreased in portions of the central and southern Great Plains – parts of Texas, Oklahoma and northeast Colorado – a region traditionally associated with Tornado Alley.

    Although Tornado Alley remains the top zone for tornadoes in the United States, other areas, including the so-called Dixie Alley that includes much of the lower Mississippi Valley region, are catching up.

    The researchers identified significant increasing tornado frequency in portions of Mississippi, Alabama, Arkansas, Missouri, Illinois, Indiana, Tennessee and Kentucky.

    2
    Image via Northern Illinois University.

    Victor Gensini is a meteorology professor at Northern Illinois University and lead author of the study, published October 17, 2018, in the peer-reviewed journal Climate and Atmospheric Science. Gensini said in a statement:

    “Regions in the Southeast and Midwest are closing the gap when it comes to the number of tornado reports.

    It’s not that Texas and Oklahoma do not get tornadoes. They’re still the number one location in terms of tornado frequency, but the trend in many locations is down over the past 40 years.”

    The researchers tracked the number of tornado reports from 1979 to 2017. The study examined tornado frequency trends in fine-scale resolution using two separate approaches, Gensini said. Read about how the researchers conducted the study here.

    Previous research has identified the U.S. Southeast as particularly vulnerable to tornadoes. Because of factors such as longer and larger tornado paths, expanding population density, mobile-home density and higher nighttime tornado probabilities, most tornado fatalities occur in the Southeast, particularly the mid-South region. Gensini said:

    “We’ve shown the tornado frequency trend is increasing in the Midwest and Southeast. While tornadoes can happen in all 50 states, if more tornadoes are happening in your area, you’re more susceptible to one of these disasters.”

    The researchers cannot say for sure whether the eastward uptick in tornado frequency might be caused by natural or human-induced climate change. Gensini said:

    “Clearly, there is a climate change signal here. What’s causing the change is still an open question.”

    Bottom line: According to a new study, U.S. tornado frequency is shifting eastward from Tornado Alley.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 10:30 am on October 22, 2018 Permalink | Reply
    Tags: , , , , EarthSky, , Gaia’s 2nd data release: 1.7 billion stars!   

    From EarthSky: “Gaia’s 2nd data release: 1.7 billion stars!” 

    1

    From EarthSky

    April 26, 2018 [Missed on first go round. Better late than never.]
    Deborah Byrd


    Gaia’s view of our home galaxy, the Milky Way, in a 360 degree interactive view (click arrows in upper left) via ESA/Gaia/DPAC; ATG medialab.

    Why did ESA’s director of science say Gaia’s observations are “redefining the foundations” of astronomy? Also, links to virtual reality resources made possible by Gaia, available for you to explore.

    It was less than a century ago, in 1920, that astronomers were famously debating the nature of so-called spiral nebulae. Some believed they lay inside our own Milky Way galaxy and were, perhaps, forming solar systems. Others thought they were large and distant separate galaxies. Thus the wisest astronomers of yesteryear couldn’t be sure of the true nature of our home galaxy, the Milky Way.

    Milky Way Galaxy Credits: NASA/JPL-Caltech/R. Hurt

    They couldn’t know it is indeed one galaxy of billions in the universe. And they couldn’t have imagined that now, just 100 years later, we’d have a space observatory like Gaia, whose goal is nothing less than to provide a 3D map of our galaxy. This mission had its second data release this week, along with a host of virtual reality resources for scientists and the public. The European Space Agency (ESA) said Gaia’s data makes possible:

    “… the richest star catalog to date, including high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home galaxy.”

    The new data, which ESA called phenomenal, is based on 22 months of Gaia’s charting of the sky. Günther Hasinger, ESA’s director of science, said:

    “The observations collected by Gaia are redefining the foundations of astronomy.”

    Why all the superlatives? What’s so amazing about Gaia’s data?

    Gaia gathers its phenomenal data in the most unglamorous of ways, via what’s called astrometry. Okay, now, hang in there with me. Think about this. Gaia’s job is to scan the sky repeatedly, observing each of its targeted billion stars an average of 70 times over its five-year mission. So, for example, we know our sun and all the stars in the Milky Way are moving continuously in great orderly masses around the center of our galaxy. We know that … but we didn’t have many details about how each star moves. How could we? The data for so many stars would be (are) massive; collecting the data, storing it and analyzing it requires today’s spacecraft and computer technologies.

    Over its five years, again and again and again, Gaia will acquire data points on the positions of Milky Way stars. Thus astronomers have already been able to produce an illustration like the very wonderful one below, which shows median velocities (the distances and directions traveled by each star per unit of time) of stars in our Milky Way.

    And so we begin to see – not just see in our minds, but actually see via Gaia’s actual data – that, due to the movements of its stars, our Milky Way galaxy is rotating, with us in its midst. You can see that in one illustration of Gaia’s data, below:

    2
    All-sky map of median velocities of about a billion stars toward or away from our sun, made possible by the Gaia mission. When you look at this map, you’re seeing a large-scale pattern caused by rotation of our Milky Way galaxy. Image via DPAC/ESA/STFC.

    And that’s just one example of the type of insight Gaia’s data can provide. ESA said:

    “Gaia was launched in December 2013 and started science operations the following year. The first data release, based on just over one year of observations, was published in 2016; it contained distances and motions of two million stars.

    The new data release, which covers the period between July 25, 2014, and May 23, 2016, pins down the positions of nearly 1.7 billion stars, and with a much greater precision. For some of the brightest stars in the survey, the level of precision equates to Earth-bound observers being able to spot a Euro coin lying on the surface of the moon.”

    Gaia is also gathering other types of data. The illustration below shows some of the ways in which Gaia sees our Milky Way:

    3
    Gaia’s all-sky view of our Milky Way galaxy and neighboring galaxies. The maps show the total brightness and color of stars (top), the total density of stars (middle) and the interstellar dust that fills the galaxy (bottom). These images are based on observations performed by the ESA satellite in each portion of the sky between July 2014 and May 2016, which were published as part of the Gaia second data release on April 25, 2018. Image via ESA.

    Virtual Reality Resources. Also, along with this second data release by Gaia, ESA has released several virtual reality resources to help visualize Gaia’s extraordinary data set, both for public outreach and for scientific purposes.

    One of the public offerings is Gaia Sky, a real-time, 3D astronomy visualisation software that runs on Windows, Linux and MacOS, developed in the framework of ESA’s Gaia mission by the Gaia group at the Astronomisches Rechen-Institut (Zentrum für Astronomie Heidelberg, University of Heidelberg, Germany). It contains a simulation of our solar system, a view of the second Gaia data release (with different selections based on parallax relative errors, ranging from a few million to hundreds of millions of stars), and additional astronomical and cosmological data to visualize star clusters, nearby galaxies, distant galaxies and quasars, and the Cosmic Microwave Background. The data are extensive, and you’ll want to explore them yourself here. ESA also offered this fun trailer for Gaia Sky:

    4
    Screen shot from Gaia Sky, a real-time, 3D astronomy visualization software that runs on Windows, Linux and MacOS.

    So you can see … there’s really a lot here to think about and explore, both for the public and for scientists. And maybe you can begin to see that – to those astronomers debating the nature of spiral nebulae in 1920 – Gaia’s data might have seemed nothing short of miraculous!

    The video at the full article shows a comparison between Gaia’s first and second data releases.

    Bottom line: The Gaia space observatory’s mission is to create a 3D map of our Milky Way galaxy. This week was its 2nd data release, consisting of high-precision measurements of some 1.7 billion stars. ESA also released a host of virtual reality resources, based on Gaia data.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 9:51 am on October 22, 2018 Permalink | Reply
    Tags: , , , , EarthSky, , Our Milky Way almost collided with another galaxy   

    From EarthSky: “Our Milky Way almost collided with another galaxy” 

    1

    From EarthSky

    October 22, 2018
    Deborah Byrd

    Astronomers found a snail-shaped substructure of stars in our larger Milky Way galaxy.

    Milky Way Galaxy Credits: NASA/JPL-Caltech/R. Hurt

    It indicates the Milky Way is still enduring the effects of a near-collision that set millions of stars moving like ripples on a pond.

    1

    How do we know our own Milky Way galaxy’s history? One way is to observe the current motions of Milky Way stars (or as current as we can get them, given the finite speed of light). A revolution in our ability to track Milky Way star motions began in late 2013, with the launch of the European Space Agency’s Gaia mission.

    ESA/GAIA satellite

    Its job is to scan the sky repeatedly, observing each of its targeted billion stars an average of 70 times over the five-year mission. In this way, Gaia will see exactly how these stars are moving; ultimately, the scientists want to use this data to construct a 3-D map of our galaxy. In the meantime, with each new release of Gaia’s data, astronomers are uncovering new insights about our galaxy. Now Gaia data have revealed a near-collision between our Milky Way and a small galaxy hundreds of millions of years ago.

    The new work is based on Gaia’s second data release. It shows that some stars in our Milky Way galaxy are moving “like ripples on a pond,” these astronomers said, due to that long-ago collision.

    The timeframe for the close encounter is about 300 to 900 million years ago. That’s relatively recent history, astronomically speaking.

    The culprit could be the Sagittarius dwarf galaxy, one of several dozen small galaxies known to accompany our larger galaxy in space. The Milky Way is in the process of cannibalizing this little galaxy, which contains only a few tens of millions of stars, in contrast to our galaxy’s 100 billion stars.

    Teresa Antoja from Universitat de Barcelona, Spain, led the research. She said:

    “At the beginning the features were very weird to us. I was a bit shocked and I thought there could be a problem with the data because the shapes are so clear.”


    Gaia’s view of our home galaxy, the Milky Way, in a 360 degree interactive view (click arrows in upper left) via ESA/Gaia/DPAC; ATG medialab.

    3
    In this all-sky map of the density of stars in our Milky Way galaxy – observed by the Gaia mission between July 2014 and May 2016 – the Sagittarius dwarf galaxy, a small satellite of the Milky Way, is leaving a stream of stars behind as an effect of our larger galaxy’s gravitational tug. This star stream from the Sagittarius dwarf is visible as an elongated feature below our galaxy’s center (pointing in the downwards direction). Image via Gaia mission/ESA.

    A statement from the Gaia mission explained:

    “The pattern was revealed because Gaia not only accurately measures the positions of more than a billion stars but also precisely measures their velocities on the plane of the sky. For a subset of a few million stars, Gaia provided an estimate of the full three-dimensional velocities, allowing a study of stellar motion using the combination of position and velocity, which is known as ‘phase space.’

    In phase space, the stellar motions revealed an interesting and totally unexpected pattern when the star’s positions were plotted against their velocities. [Antoja] couldn’t quite believe her eyes when she first saw it on her computer screen.

    One shape in particular caught her attention. It was a snail shell-like pattern in the graph that plotted the stars’ altitude above or below the plane of the galaxy against their velocity in the same direction.”

    It had never been seen before.”

    But, these astronomers said, the Gaia data had undergone multiple validation tests. They said the only conclusion they could draw was that these features do exist in the vast space of our Milky Way. And they believe the structures they see come from a near-collision. Antoja explained:

    “It is a bit like throwing a stone in a pond, which displaces the water as ripples and waves.”

    Unlike the water molecules, which settle again, the stars retain a “memory” that they were perturbed, these astronomers said:

    “This memory is found in their motions. After some time, although the ripples may no longer be easily visible in the distribution of stars, they are still there when you look in their velocities.”

    Why didn’t astronomers see them before? The technology had not advanced far enough to enable that to happen. Antoja said:

    “It looks like suddenly you have put the right glasses on and you see all the things that were not possible to see before.”

    5
    Artist’s concept of perturbations in star velocities – like ripples in a pond – newly discovered in our Milky Way galaxy by the Gaia mission. These ripples suggest a smaller galaxy nearly collided with our Milky Way, 300 to 900 million years ago. Image via ESA.

    Bottom line: A snail-shaped substructure of stars in our larger Milky Way galaxy indicates the Milky Way is still enduring the effects of a near-collision that set millions of stars moving, like ripples on a pond.

    Source: A dynamically young and perturbed Milky Way disk [Nature]

    Via ESA

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 8:37 am on September 9, 2018 Permalink | Reply
    Tags: , , , College of Charleston, , EarthSky, How black holes bring white dwarfs back to life   

    From College of Charleston via EarthSky: “How black holes bring white dwarfs back to life” 

    From College of Charleston

    Via

    EarthSky

    September 8, 2018
    Paul Scott Anderson

    White dwarfs are the dead remnants of larger, once-active stars like our sun. But black holes can reignite them.

    1
    Artist’s concept of a black hole in 47 Tucanae X9 siphoning matter off the nearby white dwarf star. Image via NASA/CXC/M. Weiss.

    NASA/Chandra X-ray Telescope

    Just like living things, stars are born, they live and then they die. But did you know that, in some cases, a “dead” star might be reignited, if only for a few seconds? That is the finding from a new peer-reviewed study by astrophysicist Chris Fragile, which was published in The Astrophysical Journal on August 16, 2018. The research focuses on computer simulations showing what happens when a star or other object passes too close to a black hole. One finding is of particular interest. The work suggests a way in which a black hole can bring a white dwarf star – the now-dead core of a once-sunlike star – fleetingly back to life.

    Specifically, if the white dwarf passes close to a black hole, then it experiences simultaneous, intense stretching and compression, caused by the overwhelming tidal force from the black hole. During this tidal disruption event, which might last only seconds, nuclear fusion within the white dwarf might briefly reignite.

    It’s the process of nuclear fusion that enables “living” stars, like our sun, to shine.

    3
    Computer simulation of a white dwarf star being tidally disrupted by an intermediate-mass black hole. Image via Chris Fragile/College of Charleston.

    How likely is this scenario?

    It is possible, according to Fragile’s study, but certain conditions have to occur first. The white dwarf has to pass relatively close to a black hole of intermediate mass , that is, about 1,000 to 10,000 times the mass of our sun. The white dwarf must pass close to the hole, within its tidal radius, which indicates the distance between the black hole and white dwarf at which the gravity of the black hole exceeds that of the white dwarf. At this radius, the black hole begins to rip the white dwarf apart. But, in Fragile’s scenario, the white dwarf passes within the tidal radius of the black hole for, at most, only a few seconds. That is enough time for nuclear burning to restart inside the white dwarf and – through the process of nuclear fusion – for most of the white dwarf’s matter to be converted into other elements before the star blows itself apart.

    As of now, astronomers have not yet discovered many intermediate-mass black holes, although this doesn’t mean that large numbers of them don’t exist. It might just mean they are hard to find. Fragile said in a statement from the College of Charleston:

    “It is important to know how many intermediate-mass black holes exist, as this will help answer the question of where supermassive black holes come from [because some models suggest supermassive black holes form via accretion from intermediate-mass black holes].

    Finding intermediate-mass black holes through tidal disruption events would be a tremendous advancement.”

    As for tidal disruption events, astronomers haven’t yet observed many of those either, only about a dozen or so. None of those observed are thought to involve a white dwarf star. Tidal disruption events that do involve a white dwarf should be easily detectable, however. Fragile said such events can produce huge electromagnetic radiation outbursts and even gravitational wave signals. He said current and future observing programs, such as the All Sky Automated Survey for SuperNovae (ASASSN), the Intermediate Palomar Transient Factory and the Large Synoptic Survey Telescope (LSST) will continue to search for them.

    CTIO ASASSN

    ASAS-SN’s hardware. Off the shelf Mark Elphick-Los Cumbres Observatory


    LCOGT Las Cumbres Observatory Global Telescope Network, Haleakala Hawaii, USA, Elevation 10,023 ft (3,055 m)

    Caltech Palomar Intermediate Palomar Transient Factory telescope at the Samuel Oschin Telescope at Palomar Observatory,located in San Diego County, California, United States

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    3
    Artist’s concept of a tidal disruption event around a massive black hole. Image via NRAO/AUI/NSF/NASA.

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    Tidal disruption events that do involve white dwarfs are still being studied by computer simulations, as well. Such simulations have already found that nuclear burning should be a common outcome. Closer approaches by the white dwarf to the black hole will produce the element iron, while more distant approaches will produce calcium. There should also be short bursts of gravitational waves powerful enough to be detected by future instruments.

    The nuclear burning is an important aspect of a tidal disruption event, since the chemical makeup of the white dwarf is radically altered. The previous helium, carbon and oxygen found in a white dwarf are converted to elements closer to iron on the periodic table. Some of that affected material is flung out into space, where it will contribute to the birth of new stars and planets.

    4
    White dwarf star Sirius B, compared in size to Earth – about the same size, but with a gravitational field 350,000 times greater. White dwarfs are the dead remnants of once larger, active stars like the sun, and sometimes, it seems, black holes can momentarily “bring them back to life.” Image via ESA.

    Black holes are often depicted as tearing apart any object that comes too close to them; that may be pretty much true, but sometimes that violent event can apparently also, at least very temporarily, reignite a star under certain circumstances. It’s a good example of how bizarre and unexpected the universe can be, and how modern technology can help find cosmic phenomena that were never even known to occur or exist before.

    Bottom line: Tidal disruption events involving intermediate-mass black holes and white dwarf stars seem to be fairly rare, but they can seemingly do something that sounds impossible – briefly bring a star back to life.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    With our stellar location, vibrant student life and devoted faculty, the College of Charleston is truly one of the nation’s great public universities. Learn more about what the College has to offer, from our rich history to the latest state-of-the-art facilities.
    Academics

    60 majors
    78 minors
    22 master’s degree programs
    9 graduate-level certificate programs
    15:1 student/faculty ratio

    Academic Divisions

    School of the Arts
    School of Business
    School of Education, Health, and Human Performance
    School of Humanities and Social Sciences
    School of Languages, Cultures, and World Affairs
    School of Sciences and Mathematics
    Honors College
    The Graduate School of the College of Charleston
    The School of Professional Studies

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: