FYFD

Category: Research

  • A Shallow Origin for the Sun’s Magnetic Field

    A Shallow Origin for the Sun’s Magnetic Field

    The Sun‘s complex magnetic field drives its 11-year solar activity cycle in ways we have yet to understand. During active periods, more sunspots appear, along with roiling flows within the Sun that scientists track through helioseismology. Longstanding theories posit that the Sun’s magnetic field has a deep origin, about 210,000 kilometers below the surface. But new measurements have prompted an alternate theory: that the Sun’s magnetic field originates in its outer 5-10% due to a magnetorotational instability.

    Magnetorotational instabilities are usually associated with the accretion disks around black holes and other massive objects. When an electrically-conductive fluid — like the Sun’s plasma — is rotating, even a small deviation in its path can get magnified by a magnetic field. In accretion disks, these little disruptions grow until the disk becomes turbulent.

    By applying this idea to the sun, researchers found they were better able to match measurements of the plasma flows beneath the Sun’s surface. With measurements from future heliophysics missions, they believe they can work out the mechanisms driving sunspot formation, which would help us better predict solar storms that can damage electronics here on Earth. (Image credit: NASA/SDO/AIA/LMSAL; research credit: G. Vasil et al.; via Physics World)

  • Sensing Sound Like Spiderwebs

    Sensing Sound Like Spiderwebs

    Most microphones — like our ears — work by sensing the tiny pressure changes caused by a sound wave‘s passing. But for microphones built this way, the smaller they get, the more sensitive they are to thermal noise. That’s one reason that the tiny microphones in a laptop or webcam just don’t sound as good as larger mics.

    Researchers turned to nature to look for alternative ways to measure sound and zeroed in on the mechanism spiders use. Spiders “listen” to their web’s vibrations; the tiny strands of silk quiver as air flow from a sound moves past. Instead of being pressure-based, this mechanism uses viscous drag to register a sound.

    The team fabricated an array of microbeams to test the concept of a viscosity-based microphone and found that tiny beams sensed sounds just as well as larger ones. That means these microphones can get smaller without sacrificing performance. For now, they’re not as sensitive as conventional microphones, but that’s not surprising, given that engineers have been improving pressure-based microphones for 150 years. It’s a promising start for a new technology, though. (Image credit: N. Fewings; research credit: J. Lai et al.; via APS Physics)

  • Universal Wingbeats

    Universal Wingbeats

    Eagles, butterflies, and whales don’t appear to have much in common, but a new study shows that they — along with over 400 other flying and swimming animals of all sizes — flap with a frequency determined by a simple equation. Their beat frequency is proportional to the square root of their mass divided by their wing area. As you can see in the graph below, this scaling collapses pretty much all of the data onto a single line:

    Illustration of the predicted relationship between size and wing freequency (black line) shown alongside various insects, birds, bats, penguins, and whales. The swimming animals also fall on the line, once adjustments are made for the difference in density between air and water.
    Illustration of the predicted relationship between size and wing frequency (black line) shown alongside various insects, birds, bats, penguins, and whales. The swimming animals also fall on the line, once adjustments are made for the difference in density between air and water.

    It’s surprising to find such a consistent relationship among animals of such vastly different sizes and types. The next big question for researchers will be unpicking exactly why and how animals evolved to use such a consistent pattern between their size and their wing(/fin) frequency. (Image credit: top – E. Ward, graph – J. Jensen et al.; research credit: J. Jensen et al.; via Physics World)

  • Rocky Exoplanet With an Atmosphere

    Rocky Exoplanet With an Atmosphere

    In the past few decades, the number of exoplanets we’ve found has ballooned to over 5,000, but most of these worlds are gas giants closer to Jupiter than our rocky Earth. But a recent study has turned up evidence of a rocky exoplanet that, like Earth, has an atmosphere made up of more than hydrogen.

    By combining observations from the JWST with those from other telescopes, the team found that 55 Cancri e — an exoplanet nearly 9 times more massive than Earth in a system about 41 light years from us — probably has an atmosphere made up of carbon dioxide or carbon monoxide. 55 Cancri e is still a planet extremely unlike our own, though; it’s tidally locked to its star so that one side always faces the star, and its equilibrium temperature is an estimated 2000 Kelvin. That’s actually a lower temperature than expected, indicating that an atmosphere is helping distribute heat around the planet. Based on the JWST measurements, the researchers suggest that the planet’s volatile atmosphere could be supported by outgassing from a magma ocean. (Image credit: NASA/ESA/CSA/R. Crawford; research credit: R. Hu et al.; via Gizmodo)

  • Melting Permafrost Stains Alaskan Rivers Orange

    Melting Permafrost Stains Alaskan Rivers Orange

    The swiftly melting permafrost of the Arctic is releasing toxic metals like zinc, cadmium, and iron into Alaskan waterways. The contaminant levels are so high that it’s staining many rivers orange — a feature that can be seen from space. A new study identified at least 75 affected rivers in the Brooks mountain range.

    In addition to staining the rivers, these metals make the water acidic, with some waterways reaching a pH as low as 2.3, similar to the acidity of vinegar. The combination is deadly to aquatic life in the rivers, and the acidity, unfortunately, will accelerate the dissolution of rocks that can release even more metals into the water. (Image credit: K. Hill/National Park Service; research credit: J. O’Donnell et al.; via LiveScience; submitted by Emily R.)

    A contaminated portion of the Kutuk River runs orange alongside an uncontaminated portion of the same waterway.
    A contaminated portion of the Kutuk River runs orange alongside an uncontaminated portion of the same waterway.
  • Venus Flower Basket Sponges

    Venus Flower Basket Sponges

    Venus flower basket sponges have an elaborate, vase-like skeleton pocked with holes that allow water to pass through the organism. A recent numerical study looked at how the sponge’s shape deflects incoming (horizontal) ocean currents into a vertical flow the sponge can use to filter out food.

    The sponges’ structure is porous and lined with helical structures. In their simulation, researchers reproduced a version of this structure (shown below) that used none of the real sponge’s active pumping mechanisms. The digital sponge was, instead, purely passive. Nevertheless, the simulation showed that, by their skeletal structure alone, sponges could redirect a significant fraction of incoming flow toward its filtering surfaces. Interestingly, the highest deflection fraction occurred at relatively low flow speeds, showing that the sponges are set up so that their structure is especially helpful for scavenging nutrients from nearly-still waters.

    In the real world, these sponges use a combination of passive filtering and active pumping to capture their food, but this study shows that the sponge’s clever structure helps it save energy, especially in tough flow conditions. (Image credit: sponges – NOAA, simulation – G. Falcucci et al.; research credit: G. Falcucci et al.; via APS Physics)

    A detail from a numerical simulation shows streamlines around and inside a model sponge.
    A detail from a numerical simulation shows streamlines around and inside a model sponge.
  • Slipping Along Enceladus

    Slipping Along Enceladus

    Home to a sub-surface ocean, Saturn‘s moon Enceladus is a fascinating candidate for life in our solar system. As it orbits Saturn, plumes periodically shoot out long surface features known as tiger stripes that sit near the icy moon’s southern pole. A recent study, based on numerical simulation, suggests a geophysical mechanism that could account for the plumes.

    The team suggests that, like the San Andreas Fault, the tiger stripes are a fault subject to strike-slip motion. In this type of fault, the ice on either side meets along a vertical face and the two sides will slide past one another in opposite directions. As Enceladus orbits, its proximity to Saturn causes tidal compression across the fault that modulates how much slip motion occurs. In their model, the authors found that strike-slip motion would intermittently open gaps in the fault that would allow water from the subsurface ocean to create plumes at intervals consistent with those observed. (Image credit: top – NASA/JPL-Caltech/Space Science Institute, illustration – A. Berne et al.; research credit: A. Berne et al.; via Gizmodo)

    Illustration of the strike-slip mechanism over the course of Enceladus's tides. The two sides of the "tiger stripe" fault move in opposite directions. How much they move depends on the amount of tidal compression caused by Enceladus's orbit around Saturn. At times, motion along the fault pulls apart narrow sections of the ice, allowing a plume to spray out.
    Illustration of the strike-slip mechanism over the course of Enceladus’s tides. The two sides of the “tiger stripe” fault move in opposite directions. How much they move depends on the amount of tidal compression caused by Enceladus’s orbit around Saturn. At times, motion along the fault pulls apart narrow sections of the ice, allowing a plume to spray out.
  • Searching for Stability in Cleaner Flames

    Searching for Stability in Cleaner Flames

    Spiking natural gas power plants with hydrogen could help them burn cleaner as we transition away from carbon power. But burners in power plants and jet engines can be extremely finicky, thanks to thermoacoustic instabilities. As a flame burns, it can sputter and fluctuate in its heat output. That creates pressure oscillations (which we sometimes hear as sound waves) that reflect off the burner’s walls and return toward the flame, causing further fluctuations. This feedback loop can be destructive enough to explode combustion chambers.

    Adding hydrogen to a burner designed purely for natural gas can trigger these instabilities (above image), but researchers hope that by exploring fuel-mixtures and their effect at lab-scale, they can help designers find safe ways to adapt industrial burners for the cleaner fuel mixture. (Image and research credit: B. Ahn et al.; via APS Physics)

  • Making Reconfigurable Liquid Circuits

    Making Reconfigurable Liquid Circuits

    Microfluidic circuits are key to “labs on a chip” used in medical diagnostics, inkjet printing, and basic research. Typically, channels in these circuits are printed or etched onto solid surfaces, making it difficult to reconfigure them. A group in China developed an alternative design, inspired by reconfigurable toys like Lego blocks. Their set-up, shown above, uses a pillared surface immersed in oil. To create the channels, they pipette water — one droplet at a time — into the space between pillars. The combination of oil and pillars traps the drop. With multiple drops linked together, they get channels, like the ones above that mix two fluids. When the time comes to reconfigure the channels, they just pipette the water out and cut the channel with a sheet of coated paper. (Image and research credit: Y. Zeng et al.; via Physics Today)

  • How Venus Is Losing Its Water

    How Venus Is Losing Its Water

    Since Venus formed at the same time as Earth and is similar in size, scientists believe it once had the same amount of water our planet does. Today, hellish Venus has hardly any water, a fact scientists have struggled to explain completely. Most of its water was lost long ago, as incoming particles from the solar wind stripped water from the upper atmosphere; unlike Earth, Venus doesn’t enjoy the protection of a magnetic field.

    But that mechanism doesn’t explain just how arid Venus is now. A new study instead suggests that Venus’s water loss is ongoing, driven by simple chemical reactions. The team found that molecules of HCO+ (an ion made from one hydrogen, one carbon, and one oxygen atom) could mix with any remaining water to form a positively-charged molecule. Due to that charge, the chemical easily attracts loose electrons. Once combined, however, the resulting molecule is too energetic and breaks apart; when it does so, it releases highly-energetic hydrogen, which escapes the atmosphere into space. Without that hydrogen, water molecules can’t reform. This process of dissociative recombination could explain why the rest of Venus’s water has disappeared.

    Science missions that have flown to Venus so far haven’t been equipped to measure HCO+, and the authors recommend this as a priority for future missions to our neighbor. With that data, we could confirm or disprove this mechanism for Venusian water loss. (Image credit: NASA; research credit: M. Chaffin et al.; via Gizmodo)