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Category: physics – Page 224

A dynamo mechanism could explain the incredibly strong magnetic fields in white dwarf stars according to an international team of scientists, including a University of Warwick astronomer.

One of the most striking phenomena in astrophysics is the presence of magnetic fields. Like the Earth, and stellar remnants such as have one. It is known that the magnetic fields of white dwarfs can be a million times stronger than that of the Earth. However, their origin has been a mystery since the discovery of the first magnetic white dwarf in the 1970s. Several theories have been proposed, but none of them has been able to explain the different occurrence rates of magnetic white dwarfs, both as individual stars and in different binary star environments.

This uncertainty may be resolved thanks to research by an international team of astrophysicists, including Professor Boris Gänsicke from the University of Warwick and led by Professor Dr. Matthias Schreiber from Núcleo Milenio de Formación Planetaria at Universidad Santa María in Chile. The team showed that a dynamo mechanism similar to the one that generates magnetic fields on Earth and other planets can work in white dwarfs, and produce much stronger fields. This research, part-funded by the Science and Technology Facilities Council (STFC) and the Leverhulme Trust, has been published in the prestigious scientific journal Nature Astronomy.

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Chemical organization in reaction-diffusion systems offer a strategy to generate materials with ordered morphologies and architecture. Periodic structures can be formed using molecules or nanoparticles. An emerging frontier in materials science aims to combine nanoparticles and molecules. In a new report on Science Advances, Amanda J. Ackroyd and a team of scientists in chemistry, physics and nanomaterials in Canada, Hungary and the U.S. noted how solvent evaporation from a suspension of cellulose nanocrystals (CNCs) and L-(+)-tartaric acid [abbreviated L-(+)-TA] caused the phase separation of precipitation to result in the rhythmic alteration of CNC-rich, L-(+)-TA rings. The CNC-rich regions maintained a cholesteric structure, while the L-(+)-TA-rich bands formed via radially elongated bundles to expand the knowledge of self-organizing reaction-diffusion systems and offer a strategy to design self-organizing materials.

Chemical organization

The process of self-organization and self-assembly occurs universally in non-equilibrium systems of living matter, geochemical environments, materials science and in industry. Existing experiments that lead to can be divided into two groups including the classical Liesegang-type experiments and chemical organization via periodic precipitation to generate materials with ordered morphologies and structural hierarchy. In this work, Ackroyd et al. developed a strategy for solvent evaporation to phase separate an aqueous solution of tartaric acid/cellulose nanocrystals [L-(+)-TA/CNC or TA/CNC] for its subsequent precipitation to result in a rhythmic alternation of CNC-rich or CNC-depleted ring-type regions. The team developed a kinetic model which agreed with the quantitatively. The work expands the range of self-organizing reaction-diffusion systems to pave the way for periodically structured functional materials.

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An international research team led by Michigan State University has helped create cosmic conditions at RIKEN’s heavy-ion accelerator in Japan.

Imagine taking all of the water in Lake Michigan — more than a quadrillion gallons — and squeezing it into a 4-gallon bucket, the kind you’d find at a hardware store.

A quick review of the numbers suggests that this should be impossible: that’s too much stuff and not enough space. But this outlandish density is a defining feature of celestial objects known as neutron stars. These stars are only about 15 miles across, yet they hold more mass than our sun thanks to some extreme physics.

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A breakthrough astrophysics code, named Octo-Tiger, simulates the evolution of self-gravitating and rotating systems of arbitrary geometry using adaptive mesh refinement and a new method to parallelize the code to achieve superior speeds.

This new code to model stellar collisions is more expeditious than the established code used for . The research came from a unique collaboration between experimental computer scientists and astrophysicists in the Louisiana State University Department of Physics & Astronomy, the LSU Center for Computation & Technology, Indiana University Kokomo and Macquarie University, Australia, culminating in over of a year of benchmark testing and scientific simulations, supported by multiple NSF grants, including one specifically designed to break the barrier between computer science and astrophysics.

“Thanks to a significant effort across this collaboration, we now have a reliable computational framework to simulate stellar mergers,” said Patrick Motl, professor of physics at Indiana University Kokomo. “By substantially reducing the to complete a simulation, we can begin to ask new questions that could not be addressed when a single-merger simulation was precious and very time consuming. We can explore more parameter space, examine a simulation at very high spatial resolution or for longer times after a merger, and we can extend the simulations to include more complete physical models by incorporating radiative transfer, for example.”

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This shows also the hertz of reality circa 2016.

Long ago, deep in space, two massive black holes—the ultrastrong gravitational fields left behind by gigantic stars that collapsed to infinitesimal points—slowly drew together. The stellar ghosts spiraled ever closer, until, about 1.3 billion years ago, they whirled about each other at half the speed of light and finally merged. The collision sent a shudder through the universe: ripples in the fabric of space and time called gravitational waves. Five months ago, they washed past Earth. And, for the first time, physicists detected the waves, fulfilling a 4-decade quest and opening new eyes on the heavens.

Here’s the first person to spot those gravitational waves

The discovery marks a triumph for the 1000 physicists with the Laser Interferometer Gravitational-Wave Observatory (LIGO), a pair of gigantic instruments in Hanford, Washington, and Livingston, Louisiana. Rumors of the detection had circulated for months. Today, at a press conference in Washington, D.C., the LIGO team made it official. “We did it!” says David Reitze, a physicist and LIGO executive director at the California Institute of Technology (Caltech) in Pasadena. “All the rumors swirling around out there got most of it right.”

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Hebrew University Researcher Introduces New Approach to Three-Body Problem, Predicts its Outcome Statistics.

The “three-body problem,” the term coined for predicting the motion of three gravitating bodies in space, is essential for understanding a variety of astrophysical processes as well as a large class of mechanical problems, and has occupied some of the world’s best physicists, astronomers and mathematicians for over three centuries. Their attempts have led to the discovery of several important fields of science; yet its solution remained a mystery.

At the end of the 17th century, Sir Isaac Newton succeeded in explaining the motion of the planets around the sun through a law of universal gravitation. He also sought to explain the motion of the moon. Since both the earth and the sun determine the motion of the moon, Newton became interested in the problem of predicting the motion of three bodies moving in space under the influence of their mutual gravitational attraction (see illustration to the right), a problem that later became known as “the three-body problem.”

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Auroral displays continue to intrigue scientists, whether the bright lights shine over Earth or over another planet. The lights hold clues to the makeup of a planet’s magnetic field and how that field operates.

New research about Jupiter proves that point — and adds to the intrigue.

Peter Delamere, a professor of space physics at the University of Alaska Fairbanks Geophysical Institute, is among an international team of 13 researchers who have made a key discovery related to the aurora of our solar system’s largest planet.

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Stephen Hawking thought an asteroid impact posed the greatest threat to life on Earth. Thanks to Kiwico for sponsoring this video. For 50% off your first month of any crate, go to https://kiwico.com/veritasium50
For other potential world ending catastrophes, check out Domain of Science: https://ve42.co/DoS

Special thanks to:
Prof. Dave Jewitt from UCLA Earth, Planetary, and Space Sciences.
Prof. Mark Boslough from Sandia National Labs.
Scott Manley: https://www.youtube.com/user/szyzyg.
Ryan Wyatt at Morrison Planetarium.
Prof. Amy Mainzer.
Alexandr Ivanov for the opening shot of Chelyabinsk Meteor.

Maps of Asteroid Impacts —https://ve42.co/Map.

Time passing animation from Universe Sandbox — http://universesandbox.com/

Opposition Effect — https://ve42.co/Belskaya2000
Belskaya, I. N., & Shevchenko, V. G. (2000). Opposition effect of asteroids. Icarus, 147, 94–105.

Potentially Hazardous Asteroids — https://ve42.co/Perna2013

Continue reading “These are the asteroids to worry about” | >