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Category: space – Page 5

At extremely high densities, quarks are expected to form pairs, as electrons do in a superconductor. This high-density quark behavior is called color superconductivity. The strength of pairing inside a color superconductor is difficult to calculate, but scientists have long known the strength’s relationship to the pressure of dense matter. Measuring the size of neutron stars and how they deform during mergers tells us their pressure and confirms that neutron stars are indeed the densest visible matter in the universe.

In a recent study, researchers used neutron star observations to infer the properties of quark matter at even higher densities where it is certain to be a color superconductor. This yields the first empirical upper bound on the strength of color superconducting pairing.

The work is published in the journal Physical Review Letters.

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Back in the old days—the really old days—the task of designing materials was laborious. Investigators, over the course of 1,000-plus years, tried to make gold by combining things like lead, mercury, and sulfur, mixed in what they hoped would be just the right proportions. Even famous scientists like Tycho Brahe, Robert Boyle, and Isaac Newton tried their hands at the fruitless endeavor we call alchemy.

Materials science has, of course, come a long way. For the past 150 years, researchers have had the benefit of the periodic table of elements upon which to draw, which tells them that different elements have different properties, and one can’t magically transform into another. Moreover, in the past decade or so, machine learning tools have considerably boosted our capacity to determine the structure and physical properties of various and substances.

New research by a group led by Ju Li—the Tokyo Electric Power Company Professor of Nuclear Engineering at MIT and professor of and engineering—offers the promise of a major leap in capabilities that can facilitate materials design. The results of their investigation appear in Nature Computational Science.

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The star HD 65,907 is not what it appears to be. It’s a star that looks young, but on closer inspection, it is actually much, much older. What’s going on? Research suggests that it is a resurrected star.

Astronomers employ different methods to measure a star’s age. One is based on its brightness and temperature. All stars follow a particular path in life, known as the main sequence. The moment they begin fusing hydrogen in their cores, they maintain a strict relationship between their brightness and temperature. By measuring these two properties, astronomers can roughly pin down the age of a star.

But there are other techniques, like measuring the amount of heavy elements in a stellar atmosphere. Older stars tend to have fewer of these elements, because they were born at a time before the galaxy had become enriched with them.

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The Perfect Cosmic Fireball

Astronomers have unveiled the extraordinary details of a nearly perfect spherical explosion—a kilonova—caused by the collision of two neutron stars. This dramatic event unfolded in 2017 in the galaxy NGC 4,993, located 140–150 million light years from Earth in the Hydra constellation. With a combined mass of 2.7 times that of the sun, the neutron stars had orbited each other for billions of years before their explosive merger.

Lead researcher Albert Sneppen of the Cosmic Dawn Center described the event as “a perfect explosion” due to its symmetry and scientific implications. The kilonova’s luminous fireball emitted a light equivalent to a billion suns for several days, dwarfing any earthly nuclear explosion in intensity.

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Collapsed dead stars, known as neutron stars, are a trillion times denser than lead, and their surface features are largely unknown. Nuclear theorists have explored mountain building mechanisms active on the moons and planets in our solar system. Some of these mechanisms suggest that neutron stars are likely to have mountains.

Neutron star “mountains” would be much more massive than any on Earth—so massive that gravity just from these mountains could produce small oscillations, or ripples, in the fabric of space and time.

Mountains, or non-axisymmetric deformations of rotating neutron stars, efficiently radiate gravitational waves. In a study published in the journal Physical Review D, nuclear theorists at Indiana University consider analogies between neutron star mountains and surface features of solar system bodies.

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The mechanisms resulting in particle acceleration to relativistic energies in space plasmas are an open question. Here, the authors show a reinforced shock acceleration model which enables electrons to efficiently achieve relativistic energies and reveal a low electron injection threshold.

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Emily Simpson has loved space since she was a 10-year-old kid celebrating her birthday at a planetarium. Now a recent Florida Tech graduate, she leaves with not only a dual degree in planetary science and astronomy and astrophysics but with published research, too. She mapped our solar system’s “alternate fate” had it housed an extra planet between Mars and Jupiter instead of the existing asteroid belt.

Simpson’s paper, “How might a planet between Mars and Jupiter influence the inner solar system? Effects on , obliquity, and eccentricity,” was published in Icarus, a journal devoted to the publication of research around solar system studies. It was co-authored by her advisor, assistant professor of Howard Chen.

They developed a 3D model that simulates how the solar system’s orbital architecture may have evolved differently with the formation of a planet that is at least twice the size of Earth’s mass—a super-Earth—instead of an asteroid belt.

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The amorphous state of matter is the most abundant form of visible matter in the universe, and includes all structurally disordered systems, such as biological cells or essential materials like glass and polymers.

An is a solid whose molecules and atoms form disordered structures, meaning that they do not occupy regular, well-defined positions in space.

This is the opposite of what happens in crystals, whose ordered structure facilitates their , as well as the identification of those “defects,” which practically control the physical properties of crystals, such as their plastic yielding and melting, or the way an electric current propagates through them.

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