NASA’s Perseverance rover has uncovered powerful new evidence that Mars’ Jezero Crater once hosted multiple rounds of flowing water, each creating conditions that could have supported life.
Category: space
Scientists find an explanation for odd-ball, water-rich exoplanets: They make their own water
As more and more exoplanets are discovered throughout the galaxy, scientists find some that defy explanation—at least for awhile. A new study, published in Nature, describes a process that might explain why a large portion of exoplanets have water on their surface, even when it doesn’t make sense.
Water where it shouldn’t be A particular category of exoplanets that are between the size of Earth and Neptune, referred to as “sub-Neptunes,” generally have a rocky core, which is surrounded by an envelope of either hydrogen or water. This makes sense if the planet forms farther away from its host planet, in a region where water can precipitate as ice. However, some of these planets are found much closer to their host stars, where it should be too hot to hold water at the surface.
While some planets may accumulate a certain amount of water from incoming comets and asteroids, that doesn’t work for these planets either. The amount of water that is typically found on their surfaces is too high for such explanations. Past experiments have also shown that hydrogen can reduce iron in silicates, producing water. However, they came to the conclusion that only small amounts of water would be produced at the kind of high pressures experienced at the surface of a sub-Neptune planet.
Quantum nonlocality may be inherent in the very nature of identical particles
At its deepest physical foundations, the world appears to be nonlocal: particles separated in space behave not as independent quantum systems, but as parts of a single one. Polish physicists have now shown that such nonlocality—arising from the simple fact that all particles of the same type are indistinguishable—can be observed experimentally for virtually all states of identical particles.
All particles of the same type—for example, photons or electrons—are entangled with one another, including those on Earth and those in the most distant galaxies. This surprising statement follows from a fundamental postulate of quantum mechanics: particles of the same type are, in their very nature, identical. Does this mean that a universal source of entanglement—underlying the peculiar, nonlocal features of the quantum world—is at our fingertips? And can we somehow outsmart quantum theory, which so carefully guards access to this extraordinary resource?
Answers to these questions have been provided by two Polish theorists from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Krakow and the Institute of Theoretical and Applied Informatics of the Polish Academy of Sciences (IITiS PAN) in Gliwice. Their findings, published in npj Quantum Information, show how the very identity of particles gives rise to observable quantum nonlocality.
Sounds modify visual perception: New links between hearing and vision in the rodent brain
Sounds can alter the way the brain interprets what it sees. This is the key finding of a new study by SISSA researchers in Trieste, published in PLOS Computational Biology. The research shows that, when sounds are paired with moving visual stimuli, the latter are perceived differently by rats. In particular, auditory cues systematically alter vision by compressing the animals’ “perceptual space.”
Derived from the integration of behavioral experiments and computational modeling, the researchers’ findings indicate that auditory signals exert an inhibitory influence on visual perception. The study thus provides a new perspective on how the senses communicate within the brain, revealing that even direct connections between primary sensory areas—not only integration within higher-order association cortices—can profoundly influence perceptual experience.
Nearby pulsar offers insights into emission physics near the death line
Using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), astronomers from the Chinese Academy of Sciences (CAS) and elsewhere have observed a nearby pulsar known as PSR J2129+4119. Results of the observational campaign, published October 30 on the arXiv pre-print server, deliver important insights into the behavior and properties of this pulsar.
Radio emission from pulsars exhibits a variety of phenomena, including subpulse drifting, nulling, or mode changing. In the case of subpulse drifting, radio emission from a pulsar appears to drift in spin phase within the main pulse profile. When it comes to nulling, the emission from a pulsar ceases abruptly from a few to hundreds of pulse periods before it is restored.
Discovered in 2017, PSR J2129+4119 is an old and nearby pulsar located some 7,500 light years away. It has a pulse period of 1.69 seconds, dispersion measure of 31 cm/pc3, and characteristic age of 342.8 million years. The pulsar lies below the so-called “death line”—a theoretical boundary in the period-period derivative diagram below which the coherent radio emission is sustained.
Dying Stars Are Swallowing Their Giant Planets
“This is strong evidence that as stars evolve off their main sequence they can quickly cause planets to spiral into them and be destroyed,” said Dr. Edward Bryant.
What happens to planets as their stars age and come closer to death? This is what a recent study published in the Monthly Notices of the Royal Astronomical Society hopes to address as a team of researchers investigated the interaction between stars near the end of their lifetimes and their exoplanets with short-period orbits. This study has the potential to help scientists better understand the evolution of stars and what this could mean for our Sun near the end of its lifetime.
For the study, the researchers analyzed data obtained from NASA’s Transiting Exoplanet Survey Satellite (TESS) mission for short-period exoplanets orbiting post-main-sequence stars, which are stars approximately the size of our Sun which have exhausted their hydrogen and have ballooned into red giants. Additionally, these short-period exoplanets have orbits that last mere days.
The goal of the study was to ascertain the influence of these red giants on their planetary populations, with the researchers settling on 130 exoplanets after careful data analysis. In the end, the researchers found that only 0.28 percent of older post-main sequence stars had giant exoplanets, with 0.35 percent of younger post-main-sequence stars having giant exoplanets. Finally, the researchers found only 0.11 percent of the oldest post-main-sequence stars had exoplanets.
Many mini-Neptunes once thought to be lava worlds may actually have solid surfaces
As telescopes have become more powerful, it’s turned out our solar system is not the only game in town: There are millions of other planets out there in the galaxy. But we’re still teasing out clues about what they are actually like.
One of the puzzles is a kind of planet that appears to be one of the most common types in the universe. Known as “mini-Neptunes” because they run a little smaller than Neptune in our solar system, these planets are made of some mix of rock and metal, with thick atmospheres mostly made of hydrogen, helium, and perhaps water. Strangely, despite their abundance elsewhere, they have no analog in our own solar system, making the population something of an enigma.
But a new study published Nov. 5, led by Prof. Eliza Kempton with the University of Chicago, adds a new wrinkle to our best picture yet of these distant worlds. The research is published in The Astrophysical Journal Letters.