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Category: space

Measuring how materials hotter than the sun’s surface conduct electricity

Warm dense matter is a state of matter that forms at extreme temperatures and pressures, like those found at the center of most stars and many planets, including Earth. It also plays a role in the generation of Earth’s magnetic field and in the process of nuclear fusion.

Although warm dense matter is found all over the universe, researchers don’t have many good theories to describe the physics of materials under those conditions. Measurements of a material’s electrical conductivity would help test and refine models of warm dense matter. However, classic probes for such measurements require contact with the material. These can’t be used because materials in a warm dense matter state are very hot, often as hot or even hotter than the surface of the sun. Consequently, information about the electrical conductivity has so far been inferred indirectly.

In other words, without direct measurements, “there’s a lot of stuff in the universe happening that we as physicists are still struggling to understand,” said Ben Ofori-Okai, assistant professor at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University and a researcher at the Stanford PULSE Institute.

New moonquake discovery could change NASA’s Moon plans

Moonquakes shook Apollo 17’s landing zone—and they could challenge the safety of future lunar outposts. Scientists have discovered that moonquakes, not meteoroids, are responsible for shifting terrain near the Apollo 17 landing site. Their analysis points to a still-active fault that has been generating quakes for millions of years. While the danger to short missions is low, long-term lunar bases could face increasing risk. The findings urge future planners to avoid building near scarps and to prioritize new seismic instruments.

A recently published study reports that shaking from moonquakes, rather than impacts from meteoroids, was the main force behind the shifting terrain in the Taurus-Littrow valley, the site where Apollo 17 astronauts landed in 1972. The researchers also identified a likely explanation for the changing surface features and evaluated potential damage by applying updated models of lunar seismic activity — results that could influence how future missions and long-term settlements are planned on the moon.

The work, conducted by Smithsonian Senior Scientist Emeritus Thomas R. Watters and University of Maryland Associate Professor of Geology Nicholas Schmerr, appeared in the journal Science Advances.

Comet 3I/ATLAS: Europa Clipper captures rare ultraviolet view

The Southwest Research Institute-led Ultraviolet Spectrograph (UVS) aboard NASA’s Europa Clipper spacecraft has made valuable observations of the interstellar comet 3I/ATLAS, which in July became the third officially recognized interstellar object to cross into our solar system. UVS had a unique view of the object during a period when Mars- and Earth-based observations were impractical or impossible.

Conventional entanglement can have thousands of hidden topologies in high dimensions

Researchers from the University of the Witwatersrand in South Africa, in collaboration with Huzhou University, discovered that the entanglement workhorse of most quantum optics laboratories can have hidden topologies, reporting the highest ever observed in any system: 48 dimensions with over 17,000 topological signatures, an enormous alphabet for encoding robust quantum information.

Most quantum optics laboratories produce entangled photons by a process of spontaneous parametric downconversion (SPDC), which naturally produces entanglement in “space,” the spatial degrees of freedom of light. Now the team have found that hidden in this space is a world of high-dimensional topologies, offering new paradigms for encoding information and making quantum information immune to noise. The topology was shown using the orbital angular momentum (OAM) of light, from two dimensional to very high dimensions.

Reporting in Nature Communications, the team showed that if one measures the OAM of two entangled photons it can be shown to have a topology: an underlying feature of the entanglement itself. Since OAM can take on an infinite number of possibilities, so too can the topology.

Color-superconducting quark matter may explain stability of massive neutron stars

Describing matter under extreme conditions, such as those found inside neutron stars, remains an unsolved problem. The density of such matter is equivalent to compressing around 100,000 Eiffel Towers into a single cubic centimeter. In particular, the properties of so-called quark matter—which consists of the universe’s fundamental building blocks, the quarks, and may exist in extremely dense regions—play a central role.

Researchers from TU Darmstadt and Goethe University Frankfurt have studied this matter and its thermodynamic properties. Their findings are published in the journal Physical Review Letters.

Theoretical studies suggest that quarks at very low temperatures enter a so-called color-superconducting state, which fundamentally alters the nature of matter. This state is analogous to the transition of an electron gas into an electrical superconductor—except that, instead of electrons, quarks pair up and create an energy gap in their excitation spectrum.

Rare brown dwarf discovered orbiting ancient star

Astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) and elsewhere report the discovery of a new brown dwarf about 60 times more massive than Jupiter. The newfound substellar object, designated TOI-7019 b, is a brown dwarf known to orbit a star that is part of the Milky Way’s ancient thick disk. The finding is detailed in a paper published December 5 on the arXiv preprint server.

Brown dwarfs (BDs) are intermediate objects between planets and stars, occupying the mass range between 13 and 80 Jupiter masses (0.012 and 0.076 solar masses). However, although many brown dwarfs have been detected to date, these objects orbiting other stars are a rare find.

Recently, a team of astronomers led by CfA’s Jea Adams Redai found another rare brown dwarf, which is a companion to the star TOI-7019. This star was initially observed with NASA’s Transiting Exoplanet Survey Satellite (TESS), which detected a transit signal in its light curve. Now, follow-up observations of this star confirmed that the transit signal is produced by a substellar object.

Hidden Patterns in Hot Jupiter Orbits Expose Their Secret Past

The first planet ever found orbiting another star was detected in 1995, and it belonged to a class now known as a “hot Jupiter.” These exoplanets are comparable in mass to Jupiter but circle their stars in just a few days. Scientists now believe that hot Jupiters originally formed far from their stars, similar to Jupiter in our Solar System, and later moved inward.

Two main processes have been proposed to explain this journey: high-eccentricity migration, where gravitational interactions with other objects distort a planet’s orbit before tidal forces near the star gradually make it circular; and disk migration, in which a planet slowly spirals inward while embedded in the protoplanetary disk of gas and dust.

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