Physics Today Daily Edition
BBC: Pluto tends to steal the show in planetary science these days, but Ceres, the solar system's largest asteroid, is offering up some surprises of its own. New data from NASA's Dawn spacecraft, presented at the Lunar and Planetary Science Conference in The Woodlands, Texas, reveal evidence of buried water ice and offer an unprecedented look at a mysterious bright region in the middle of a crater. The probe's GRaND instrument has remotely probed the chemistry of the asteroid's surface and found large concentrations of hydrogen at high latitudes. Those hydrogen atoms may be part of water molecules frozen just under the surface. The new images of Ceres's puzzling bright spot show a feature resembling a fried egg. Scientists suspect the feature is largely composed of magnesium sulfate salts that remained on the surface after the water that accompanied them vented into space. Dawn's orbit now has the probe just 385 km above the surface of Ceres.
Ars Technica: Traditional batteries use liquid electrolytes because they are very effective at transporting ions. But the chemicals can be hazardous and have a limited range of operating temperatures. A 2011 paper showed that some solid crystals could effectively transport lithium ions by creating a line of lithium atoms within the crystal structure, but the known materials were either unstable or unreasonably expensive. Now the authors of that paper have identified two more materials that overcome both problems while also doubling the conductivity. The researchers used the new materials to build batteries that had operating temperatures between −30 °C and 100 °C, a much wider range than traditional lithium-ion batteries. They also had a charge/discharge rate competitive with supercapacitors and an energy density competitive with traditional lithium-ion batteries. The researchers still face trouble finding electrodes that can work across the same temperature range.
Guardian: Over a three-year span, NASA's Kepler space telescope captured two stars going supernova. Just before one of the stars exploded, researchers spotted evidence of a shockwave and pulse of light, an event that is thought to allow the star to self-destruct. This is the first sighting with visible light and with a high level of detail. Such a pre-explosion signal had previously been seen only in x-ray images. Brad Tucker of the Australian National University and his colleagues think the other star was so large that the shockwave wasn't strong enough to escape the star's gravity. The researchers hope that further analysis of Kepler data will reveal more supernovas, especially now that the telescope's field of view has been expanded to include many galaxies.
New York Times: A study that stirred controversy among climate scientists when a draft version first circulated last year has now been published in the journal Atmospheric Chemistry and Physics. In the paper, retired NASA climate scientist James Hansen and colleagues argue that the amount of warming set as a goal at the Paris climate talks is enough to cause major climate changes by the end of this century. The researchers reached that conclusion by comparing the modern situation with a period roughly 120 000 years ago, when Earth warmed naturally to a temperature only slightly higher than current levels. In that era most of the polar ice sheets melted and sea levels were 20–30 feet (6.1–9.1 m) higher. Melting of the polar ice sheets, the researchers say, would release a large amount of freshwater that could slow or even stop the ocean's system of currents that redistribute heat around the planet. As a result, more heat would accumulate in the oceans, accelerating melting, exacerbating the temperature difference between tropical and polar regions, and triggering powerful storms. The paper cites controversial evidence for significant storms in the previous warm period. The slowdown of ocean currents is also not widely accepted by climate researchers. But its inclusion in the paper may result in reexamining the scenario using modern computer simulations that were not available when the theory was proposed more than a decade ago.
BBC: A supercomputer simulation presented at the American Physical Society meeting in Baltimore, Maryland, this week, models the human circulatory system in three dimensions. The simulated network, which tracks blood flow through all arteries larger than 1 mm across, is based on images captured by full-body CT and MRI scans of the circulatory system of a single person. Flow measurements in the simulation closely matched those of a 3D printed version of the circulatory system, both when the blood was free-flowing and when it was pulsed in a way that mimicked a heartbeat. Amanda Randles of Duke University and her team attempted the project primarily as a proof-of-concept because most previous simulations have focused on smaller sections of the circulatory system. The goal is to model how medical interventions, such as stents or other surgical modifications, might affect the system as a whole.