For decades, astronomers lumped brown dwarfs into a single category defined by mass alone—too big to be classified as planets but too small to become stars. However, this definition ignores the two very different mechanisms that can form them: the direct collapse of gas clouds and formation within the accretion disks of massive stars.
Through a new analysis of NASA’s Transiting Exoplanet Survey Satellite (TESS), astronomers led by Nino Ephremidze at Harvard University have made the clearest observation to date of a brown dwarf in orbit around a massive, aging star, potentially offering important new clues about how these planet-like bodies form. Their results have been posted to the arXiv preprint server.
The tiny bones in your fingers withstand countless taps and swipes thanks to a precise blend of materials. Flexible collagen fibers form the framework, reinforced by hard calcium phosphate hydroxyapatite crystals. This is just one of countless examples in which living organisms weave organic materials directly into inorganic crystals with exquisite precision. In a recent study published in Nature Communications, scientists attempted to recreate such precise spatial arrangements in biomimetic composite materials.
The researchers made two types of tiny diblock copolymer nanoparticles designed to mimic pseudo-proteins. The first consisted of solid spheres about 100 nanometers big, with a poly(benzyl methacrylate) core and a shell of sulfate-containing chains tagged with a red fluorescent dye. The second consisted of hollow, bubble-like particles about 300 nanometers across. They had the same polymer core but a carboxylate-rich outer shell tagged with a green fluorescent dye.
These tiny polymer nanoparticles, engineered with different sizes and compositions, much like protein molecules, sorted themselves naturally as growing calcite crystals trapped them. Instead of mixing randomly, the two types ended up in separate regions of the crystal, creating an artificial biomineral with a distinctly organized structure—all driven by differences in the nanoparticles’ surface chemistry.
The Australian redback spider (Latrodectus hasselti), a cousin of the North American black widow spider, is known to practice sexual cannibalism, which is somewhat common among spider species. However, the male Australian redback has also been observed facilitating the process with strange moves. Despite the complexity of these behaviors, a new study, published in Biology Letters, indicates that one of these behaviors arises from simple genetics, while another may be more complex.
Australian redback males perform an extraordinary mating somersault that places their abdomen near the female’s fangs while mating. Although this results in a form of self-sacrifice, the behavior can help males mate longer and father more offspring. This means that even if the female eats them, they were successful from an evolutionary point of view. Some redback spiders also exhibit abdominal narrowing, which makes it more difficult for the female to bite them during mating, delaying death long enough for the male to complete a second mating.
A close New Zealand relative of the Australian redback, the katipo spider, lacks both male self-sacrifice traits and does not exhibit cannibalistic mating behavior. Yet, the two species are capable of mating, producing hybrids. This, however, is only possible with a katipo female and redback male, since the redback female displays only aggressive behavior toward the katipo male.
Altermagnetism is a new, third type of magnetism of great interest for spin-transport applications like computer memory. If properly harnessed, it could combine the benefits of the two existing types of magnetism, ferromagnetism and antiferromagnetism, ultimately reducing or eliminating heat during information transfer and increasing the ability to miniaturize next-generation technologies. Rice University’s Pengcheng Dai recently published a paper in Physical Review X describing the first successful efforts to put a proposed altermagnetic material into a single magnetic-domain state, allowing the research team to characterize the material’s intrinsic magnetic structure.
“Altermagnets like hexagonal manganese telluride typically form multidomain structures where the magnetic forces divide into separate equivalent domains that spin in different directions to satisfy the underlying threefold rotational symmetry of the hexagonal lattice,” said Dai, the Sam and Helen Worden Professor of Physics and Astronomy.
“The signals from these coexisting domains could overlap, making it hard to know what the underlying magnetic structure actually is. Here, we were able to apply a uniaxial strain, which resulted in a single magnetic domain we could clearly resolve into the underlying magnetic structure.”
A year after its final muon magnetic anomaly announcement, the Muon g-2 collaboration reports a new measurement of a different property of the muon: its electric dipole moment. The work is published on the arXiv preprint server.
Based on an analysis of 25% of Fermilab’s experimental data, this is the most sensitive direct search for a muon EDM ever accomplished. It is the first direct search for the muon EDM conducted at the U.S. Department of Energy’s Fermi National Accelerator Laboratory and only the third search worldwide in the past 50 years.
Searches for EDMs play a vital role in particle physics; detecting an EDM could be key to better understanding the matter-antimatter asymmetry required to explain the universe we see around us. This new result shows that if a muon EDM exists, it must be smaller than what the Muon g-2 experiment can currently detect.
A research team has developed a new theoretical framework that can suppress light scattering in certain directions while enhancing it in others, even in irregularly arranged materials. The work extends research on controlling light scattering, which has traditionally centered on ordered crystal structures, into the realm of disordered systems.
Scattering—the process by which light is dispersed in multiple directions when it encounters matter—plays a critical role in determining the performance of a wide range of optical technologies, including anti-reflective coatings for eyeglasses and camera lenses, display diffusers, LiDAR sensors for autonomous vehicles, and optical communication components. Ultimately, the ability to precisely control scattering is a key determinant of competitiveness in optical technologies.
The researchers, led by Professors Sunkyu Yu and Namkyoo Park of the Department of Electrical and Computer Engineering at Seoul National University College of Engineering, in collaboration with Professor Xianji Piao of the University of Seoul, proposed a theory they call “Non-Hermitian Statistical Crystallography,” which considers not only refractive properties but also absorption and amplification.