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Thorfinn Hrolfsson
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The crispness of B&W photography
it still has a place
Kudu love!!!!! Via Lisl Moolman Wildlife Photography #Wildlife #Photography 
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Source: Royal Astronomical Society
Telescopes, the workhorse instruments of astronomy, are limited by the size of the mirror or lens they use. Using 'neural nets', a form of artificial intelligence, a group of Swiss researchers now have a way to push past that limit, offering scientists the prospect of the sharpest ever images in optical astronomy.

The diameter of its lens or mirror, the so-called aperture, fundamentally limits any telescope. In simple terms, the bigger the mirror or lens, the more light it gathers, allowing astronomers to detect fainter objects, and to observe them more clearly. A statistical concept known as 'Nyquist sampling theorem' describes the resolution limit, and hence how much detail can be seen.

The Swiss study, led by Prof Kevin Schawinski of ETH Zurich, uses the latest in machine learning technology to challenge this limit. They teach a neural network, a computational approach that simulates the neurons in a brain, what galaxies look like, and then ask it to automatically recover a blurred image and turn it into a sharp one. Just like a human, the neural net needs examples – in this case a blurred and a sharp image of the same galaxy – to learn the technique.

Their system uses two neural nets competing with each other, an emerging approach popular with the machine learning research community called a "generative adversarial network", or GAN. The whole teaching programme took just a few hours on a high performance computer.

Journal Reference:
Kevin Schawinski, Ce Zhang, Hantian Zhang, Lucas Fowler, Gokula Krishnan Santhanam. Generative Adversarial Networks recover features in astrophysical images of galaxies beyond the deconvolution limit. Monthly Notices of the Royal Astronomical Society: Letters, 2017; slx008
http://dx.doi.org/10.1093/mnrasl/slx008
https://academic.oup.com/mnrasl/article-lookup/doi/10.1093/mnrasl/slx008

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10 is the best, and 1 cute & 13 awesome

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nice!

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Source: University of California - Santa Cruz
Astronomers have found an enormous, glowing blob of gas in the distant universe, with no obvious source of power for the light it is emitting. Called an "enormous Lyman-alpha nebula" (ELAN), it is the brightest and among the largest of these rare objects, only a handful of which have been observed.

ELANs are huge blobs of gas surrounding and extending between galaxies in the intergalactic medium. They are thought to be parts of the network of filaments connecting galaxies in a vast cosmic web. Previously discovered ELANs are likely illuminated by the intense radiation from quasars, but it's not clear what is causing the hydrogen gas in the newly discovered nebula to emit Lyman-alpha radiation (a characteristic wavelength of light absorbed and emitted by hydrogen atoms).

The newly discovered nebula was found at a distance of 10 billion light years in the middle of a region with an extraordinary concentration of galaxies. Researchers found this massive overdensity of early galaxies, called a "protocluster," through a novel survey project led by Zheng Cai, a Hubble Postdoctoral Fellow at UC Santa Cruz.

"Our survey was not trying to find nebulae. We're looking for the most overdense environments in the early universe, the big cities where there are lots of galaxies," said Cai. "We found this enormous nebula in the middle of the protocluster, near the peak density."

Journal Reference:
Zheng Cai, Xiaohui Fan, Yujin Yang, Fuyan Bian, J. Xavier Prochaska, Ann Zabludoff, Ian McGreer, Zhenya Zheng, Richard Green, Sebastiano Cantalupo, Brenda Frye, Erika Hamden, Linhua Jiang, Nobunari Kashikawa, Ran Wang. Discovery of an Enormous Lyα nebula in a massive galaxy overdensity at z=2.3. Astrophysical Journal, September 2016



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Source: Imperial College London
This is the conclusion of a new study carried out by a researcher from Imperial College London. Cosmic dust particles originate from events such the arrival of comets in the inner solar system and collisions between asteroids, which pulverises them into dust. Some make it through the rapid descent through Earth’s atmosphere, providing microscopic records of some of the earliest events in our solar system.

The researcher found that cosmic dust particles containing water-rich minerals survive atmospheric entry more easily than water-free cosmic dust. Their calculations suggest the survival of water-rich cosmic dust is approximately double that of dry dust.

The reason why some of the water-rich particles survive the descent is because they contain clay minerals or mud, which have water trapped in them. During the decent through the Earth’s atmosphere, the dust turns into little droplets of molten rock, known as magma, and water inside it boils. This turns the dust into a magma foam bubble, which expands and becomes lighter and cooler, acting like a parachute.

As twice as many water-rich cosmic dust particles survive their decent to Earth, compared to water-free particles, it is likely that scientists have been analysing many more samples from ancient events involving water-rich asteroids, compared to events involving water-free asteroids. This may be skewing our understanding of the solar system.

Journal Reference:
Matthew J. Genge. Vesicular parachutes increase the abundance of micrometeorites from water-rich asteroids on Earth.. Geophysical Research Letters, 2017
http://dx.doi.org/10.1002/2016GL072490

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Source: University of Wisconsin-Madison
Plumbing a 90 million-year-old layer cake of sedimentary rock in Colorado, a team of scientists from the University of Wisconsin–Madison and Northwestern University has found evidence confirming a critical theory of how the planets in our solar system behave in their orbits around the sun.

The finding is important because it provides the first hard proof for what scientists call the “chaotic solar system,” a theory proposed in 1989 to account for small variations in the present conditions of the solar system. The variations, playing out over many millions of years, produce big changes in our planet’s climate — changes that can be reflected in the rocks that record Earth’s history.

The discovery promises not only a better understanding of the mechanics of the solar system, but also a more precise measuring stick for geologic time. Moreover, it offers a better understanding of the link between orbital variations and climate change over geologic time scales.

Using evidence from alternating layers of limestone and shale laid down over millions of years in a shallow North American seaway at the time dinosaurs held sway on Earth, the team led by UW–Madison Professor of Geoscience Stephen Meyers and Northwestern University Professor of Earth and Planetary Sciences Brad Sageman discovered the 87 million-year-old signature of a “resonance transition” between Mars and Earth. A resonance transition is the consequence of the “butterfly effect” in chaos theory. It plays on the idea that small changes in the initial conditions of a non-linear system can have large effects over time

Journal Reference:
Chao Ma, Stephen R. Meyers, Bradley B. Sageman. Theory of chaotic orbital variations confirmed by Cretaceous geological evidence. Nature, 2017; 542 (7642): 468
http://dx.doi.org/10.1038/nature21402

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Source: American Association for the Advancement of Science
Scientists have identified a neutron star that is consuming material so fast it emits more x-rays than any other. Its extreme brightness can only be explained if the star has a complex multipolar magnetic field, the researchers say. Ultraluminous x-ray sources (ULXs) are seen in some nearby galaxies and shine brighter than any x-ray source in our own galaxy.

Simple calculations show that, for such an intense amount of energy to be emitted, ULXs should be powered by black holes accreting surrounding material.

Here, using the X-ray Multi-Mirror Mission (XMM-Newton) and Nuclear Spectroscopic Telescope Array (NuSTAR) space telescopes, Gian Luca Israel and colleagues detected periodic signals in x-rays emitted by a ULX in the nearby spiral galaxy NGC 5907, indicating that it is instead powered by a spinning neutron star.

The star, known as NGC 5907 ULX, is accreting material so fast that its spin period is accelerating at astounding rates -- it evolved from 1.43 seconds in 2003 to 1.13 seconds in 2014. Its peak luminosity exceeds the Eddington limit, the theoretical maximum set by the balance between the force of radiation acting outward and the gravitational force acting inward, by roughly 1,000 times what would be expected for a neutron star.

The authors say that the only way to explain the data is if the neutron star does not have a simple (dipolar) magnetic field. Modelling shows that a strong, multipolar magnetic field could explain the extreme properties of NGC 5907 ULX and how it exceeds the Eddington limit.

Journal Reference:
Gian Luca Israel, Andrea Belfiore, Luigi Stella, Paolo Esposito, Piergiorgio Casella, Andrea De Luca, Martino Marelli, Alessandro Papitto, Matteo Perri, Simonetta Puccetti, Guillermo A. Rodríguez Castillo, David Salvetti, Andrea Tiengo, Luca Zampieri, Daniele D’Agostino, Jochen Greiner, Frank Haberl, Giovanni Novara, Ruben Salvaterra, Roberto Turolla, Mike Watson, Joern Wilms, Anna Wolter. An accreting pulsar with extreme properties drives an ultraluminous x-ray source in NGC 5907. Science, 2017; eaai8635
http://dx.doi.org/10.1126/science.aai8635


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Source: University of Cambridge
Astronomers are borrowing principles applied in biology and archaeology to build a family tree of the stars in the galaxy. By studying chemical signatures found in the stars, they are piecing together these evolutionary trees looking at how the stars formed and how they are connected to each other. The signatures act as a proxy for DNA sequences. It’s akin to chemical tagging of stars and forms the basis of a discipline astronomers refer to as Galactic archaeology.

It was Charles Darwin, who, in 1859 published his revolutionary theory that all life forms are descended from one common ancestor. This theory has informed evolutionary biology ever since but it was a chance encounter between an astronomer and an biologist over dinner at King’s College in Cambridge that got the astronomer thinking about how it could be applied to stars in the Milky Way.

Dr Paula Jofré, of the University of Cambridge’s Institute of Astronomy, describes how she set about creating a phylogenetic “tree of life” that connects a number of stars in the galaxy.

“The use of algorithms to identify families of stars is a science that is constantly under development. Phylogenetic trees add an extra dimension to our endeavours which is why this approach is so special. The branches of the tree serve to inform us about the stars’ shared history“ she says.

The team picked twenty-two stars, including the Sun, to study. The chemical elements have been carefully measured from data coming from ground-based high-resolution spectra taken with large telescopes located in the north of Chile. Once the families were identified using the chemical DNA, their evolution was studied with the help of their ages and kinematical properties obtained from the space mission Hipparcos, the precursor of Gaia, the spacecraft orbiting Earth that was launched by the European Space Agency and is almost halfway through a 5-year project to map the sky.

Journal Reference:
Paula Jofré, Payel Das, Jaume Bertranpetit, Robert Foley. Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree. Monthly Notices of the Royal Astronomical Society, 2017
http://dx.doi.org/10.1093/mnras/stx075

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Source: Carnegie Institution for Science
New work from Carnegie’s Stephen Elardo and Anat Shahar shows that interactions between iron and nickel under the extreme pressures and temperatures similar to a planetary interior can help scientists understand the period in our Solar System’s youth when planets were forming and their cores were created.

Earth and other rocky planets formed as the matter surrounding our young Sun slowly accreted. At some point in Earth’s earliest years, its core formed through a process called differentiation—when the denser materials, like iron, sunk inward toward the center. This formed the layered composition the planet has today, with an iron core and a silicate upper mantle and crust.

Scientists can’t take samples of the planets’ cores. But they can study iron chemistry to help understand the differences between Earth’s differentiation event and how the process likely worked on other planets and asteroids.

One key to researching Earth’s differentiation period is studying variations in iron isotopes in samples of ancient rocks and minerals from Earth, as well as from the Moon, and other planets or planetary bodies.

Journal Reference:
Stephen M. Elardo, Anat Shahar. Non-chondritic iron isotope ratios in planetary mantles as a result of core formation. Nature Geoscience, 2017
http://dx.doi.org/10.1038/ngeo2896
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