Explosively Jetting

Dropping water from a plastic pipette onto a pool of oil electrically charges the drop. Then, as it evaporates, it shrinks and concentrates the charges closer and closer. Eventually, the strength of the electrical charge overcomes surface tension, making the drop form a cone-shaped edge that jets out tiny, highly-charged microdrops. Afterward, the drop returns to its spherical shape… until shrinkage builds up the charge density again. This microjetting behavior can carry on for hours! (Video and image credit: M. Lin et al.; research preprint: M. Lin et al.)

#2024gofm #droplets #electrostaticCharge #fluidDynamics #jetting #magnetohydrodynamics #physics #satelliteDroplets #science #sessileDrop #surfaceTension

“Magic of the North”

Fires glow above and below in this award-winning image from photographer Josh Beames. In the foreground, lava from an Icelandic eruption spurts into the air and seeps across the landscape as it slowly cools. Above, the northern aurora ripples through the night sky, marking the dance of high-energy particles streaming into our atmosphere, guided by the lines of our magnetic field. Throw in some billowing turbulent smoke, and it’s hard to get more fluid dynamical (or beautiful!) than this. (Image credit: J. Beames/NLPOTY; via Colossal)

#aurora #eruption #fluidDynamics #fluidsAsArt #lava #magnetohydrodynamics #physics #science #solarWind #turbulence

Beneath a River of Red

A glowing arch of red, pink, and white anchors this stunning composite astrophotograph. This is a STEVE (Strong Thermal Emission Velocity Enhancement) caused by a river of fast-moving ions high in the atmosphere. Above the STEVE’s glow, the skies are red; that’s due either to the STEVE or to the heat-related glow of a Stable Auroral Red (SAR) arc. Find even more beautiful astrophotography at the artist’s website and Instagram. (Image credit: L. Leroux-Géré; via APOD)

#astronomy #atmosphericScience #aurora #fluidDynamics #magnetohydrodynamics #physics #planetaryScience #science #STEVE

A Magnetic Tsunami Warning

Tsunamis are devastating natural disasters that can strike with little to no warning for coastlines. Often the first sign of major tsunami is a drop in the sea level as water flows out to join the incoming wave. But researchers have now shown that magnetic fields can signal a coming wave, too. Because seawater is electrically conductive, its movement affects local magnetic fields, and a tsunami’s signal is large enough to be discernible. One study found that the magnetic field level changes are detectable a full minute before visible changes in the sea level. One minute may not sound like much, but in an evacuation where seconds count, it could make a big difference in saving lives. (Image credit: Jiji Press/AFP/Getty Images; research credit: Z. Lin et al.; via Gizmodo)

#fluidDynamics #geophysics #magneticField #magnetohydrodynamics #physics #science #tsunami

Reinterpreting Uranus’s Magnetosphere

NASA launched the Voyager 2 probe nearly 50 years ago, and, to date, it’s the only spacecraft to visit icy Uranus. This ice giant is one of our oddest planets — its axis is tilted so that it rotates on its side! — but a new interpretation of Voyager 2’s data suggests it’s not quite as strange as we’ve thought. Initially, Voyager 2’s data on Uranus’s magnetosphere suggested it was a very extreme place. Unlike other planets, it had energetic energy belts but no plasma. Now researchers have explained Voyager 2’s observations differently: they think the spacecraft arrived just after an intense solar wind event compressed Uranus’s magnetosphere, warping it to an extreme state. Their estimates suggest that Uranus would experience this magnetosphere state less than 5% of the time. But since Voyager 2’s data point is, so far, our only look at the planet, we just assumed this extreme was normal. (Image credit: NASA; research credit: J. Jasinski et al.; via Gizmodo)

#fluidDynamics #magnetohydrodynamics #physics #science #solarWind #Uranus

How Magnetic Fields Shape Core Flows

The Earth’s inner core is a hot, solid iron-rich alloy surrounded by a cooler, liquid outer core. The convection and rotation in this outer core creates our magnetic fields, but those magnetic fields can, in turn, affect the liquid metal flowing inside the Earth. Most of our models for these planetary flows are simplified — dropping this feedback where the flow-induced magnetic field affects the flow.

The simplification used, the Taylor-Proudman theorem, assumes that in a rotating flow, the flow won’t cross certain boundaries. (To see this in action, check out this Taylor column video.) The trouble is, our measurements of the Earth’s actual interior flows don’t obey the theorem. Instead, they show flows crossing that imaginary boundary.

To explore this problem, researchers built a “Little Earth Experiment” that placed a rotating tank (representing the Earth’s inner and outer core) filled with a transparent, magnetically-active fluid inside a giant magnetic. This setup allowed researchers to demonstrate that, in planetary-like flows, the magnetic field can create flow across the Taylor-Proudman boundary. (Image credit: C. Finley et al.; research credit: A. Pothérat et al.; via APS Physics)

#fluidDynamics #magnetohydrodynamics #physics #planetaryScience #rotatingFlow #science #TaylorColumn #TaylorProudmanTheorem

A purple glow arcs across the night sky. Just another aurora, or is it? First described in 2018, this is a STEVE — Strong Thermal Emission Velocity Enhancement. (Yes, the name “Steve” came first and the acronym came later.) Scientists still aren’t entirely sure how to classify this glowing phenomenon. Although it looks similar to an aurora, its color spectrum is continuous between 400 and 700 nanometers; classic auroras, in contrast, have a discrete spectrum dependent on which atmospheric molecules are getting stimulated by the incoming solar wind. Scientists have noticed that STEVE appears before midnight and is accompanied by a fast 5.5 km/s westward ion flow. A dawnside equivalent with an eastward ion flow was reported just this year.

With newly identified phenomena like this, the research papers are fast and furious as the scientific community searches for consensus on exactly what STEVE is and how it’s formed. But this domain is not reserved for professional astronomers alone; citizen scientists were the first to identify STEVE and open projects like Aurorasaurus continue to provide valuable data and observations. (Image credit: K. Trinder/NASA; research credit: S. Nanjo et al.; via Gizmodo)

https://fyfluiddynamics.com/2024/11/hello-steve/

#astronomy #aurora #fluidDynamics #magnetohydrodynamics #physics #science #solarWind #STEVE

This surreal image comes from an aurora on Halloween 2013. Photographer Ole C. Salomonsen captured it in Norway during one of the best auroral displays that year. The shimmering green and purple hues are the glow of oxygen and nitrogen in the upper atmosphere reacting to high-energy particles streaming in from the solar wind. These geomagnetic storms can disrupt GPS satellites, compromise radio communication, and even corrode pipelines, but they also create these stunning nighttime displays. (Image credit: O. Salomonsen; via APOD)

https://fyfluiddynamics.com/2024/10/eerie-aurora/

#aurora #fluidDynamics #fluidsAsArt #magnetohydrodynamics #physics #plasma #science #solarWind

Plasma lighters — as their name indicates — use plasma in place of burning butane. Plasma — our universe’s most common state of matter — is a gas that’s been stripped of its electrons, ionizing it so that it’s electrically and magnetically active. In these lighters (as well as other plasma generators), a high-voltage current jumps between two nodes to ignite the spark. In effect, it’s a tiny lightning bolt you can hold in your hand. (Though I don’t recommend that you try to literally hold it; plasma burns suck.) (Video and image credit: J. Rosenboom; via Nikon Small World in Motion)

https://fyfluiddynamics.com/2024/10/a-plasma-arc-lights/

#combustion #electricalField #fluidDynamics #magnetohydrodynamics #physics #plasma #science

Auroras happen when energetic particles — usually from the solar wind — interact with the atmosphere. Here on Earth, they’re most often found near the poles, where our strong global magnetic field converges, funneling particles down from space. Our neighbor Mars has no global magnetic field. Instead, its magnetic field is a hybrid of two sources: 1) induced magnetism from electric currents in the ionosphere and 2) patches of magnetized iron-rich crust. Together, they form an uneven and changeable field that deflects the solar wind less than one Mars radius above the planet’s surface. In contrast, Earth deflects the solar wind about 10-20 Earth radii away.

Discrete auroras (left panel) occur when electrons plunge down into the atmosphere on magnetic lines coming from Mars’ patchy crust. Global diffuse auroras (center panel) are caused by energetic solar storms that light up the whole atmosphere, sometimes for days at a time. In proton auroras (right panel), incoming solar protons steal electrons from native Martian hydrogen to form high-energy hydrogen atoms that cannot be magnetically deflected. Instead, they penetrate the planet’s bow shock and plunge into the atmosphere, creating a daytime aurora. (Image credit: UAE Space Agency/EMM/EMUS and NASA/MAVEN/IUVS; via Physics Today)

https://fyfluiddynamics.com/2024/09/martian-auroras/

#aurora #fluidDynamics #magneticField #magnetohydrodynamics #Mars #physics #science #solarWind

Our Sun is a maelstrom of light and heat, a constant battlefield for plasma and magnetic fields. This recent prominence, captured by Andrea Vanoni and others, bore a striking triangular shape. This fiery outburst — larger than our entire planet — formed and broke up over the course of a single day. The wavy solar surface features in the lower part of the image are solar fibrils, magnetically confined tubes of hot plasma. What changing magnetic fields might allow them to burst forth in a glorious candle of their own? (Image credit: A. Vanoni; via APOD)

https://fyfluiddynamics.com/2024/09/a-triangular-prominence/

#fluidDynamics #magneticField #magnetohydrodynamics #physics #plasma #prominence #science #solarDynamics

Once again, it’s time for a quick update of activity at the Open Journal of Astrophysics. This week we have published another batch of four papers which takes the count in Volume 7 (2024) up to 77 and the total published altogether by OJAp up to 192. Things are picking up again after the summer lull, and we’re moving towards a double century. If we keep up a steady average of four per week we’ll be at 200 per year.

In chronological order, the four papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.

First one up is “Quasi-two-dimensionality of three-dimensional, magnetically dominated, decaying turbulence” by Shreya Dwivedi, Chandranathan Anandavijayan, and Pallavi Bhat of TIFR, Bangalore, India. The paper presents an analysis of numerical simulations of MHD turbulence using Minkowski Functionals, with implications for local anisotropies revealed therein. It was published on 9th September 2024 and is in the folder marked High-Energy Astrophysical Phenomena.

Here is a screen grab of the overlay, which includes the abstract:

You can find the officially accepted version of the paper on the arXiv here.

The second paper to announce, also published on 9th September 2024, is “mochi_class: Modelling Optimisation to Compute Horndeski In class” by  Matteo Cataneo (Universität Bonn, Germany) and Emilio Bellini (SISSA, Trieste, Italy). This article presents a cosmological Einstein-Boltzmann solver adapted to work with Horndeski gravity, together with validation tests. It is in the folder Cosmology and NonGalactic Astrophysics.

You can see the overlay here:

The accepted version of this paper can be found on the arXiv here.

The third paper, published on 11th September 2024 in the folder marked High-Energy Astrophysical Phenomena, is by Jonathan Katz of Washington University, St Louis, USA. The title is “The Sources of Fast Radio Bursts” and it presents a discussion of the possible physical origin of Fast Radio Bursts, arguing that they fall into two distinct groups.

The final version accepted on arXiv is here.

Last in this batch, but by no means least, is “RMS asymmetry: a robust metric of galaxy shapes in images with varied depth and resolution” by Elizaveta Sazonova (U. Waterloo, Canada) with 15 other authors spread around the world (in Canada, USA, Australia, Italy, Chile, UK, Poland, Mexico, Germany, and Spain). This paper presents a method of quantifying distortion of galaxy images connected with mergers or other instabilities. It is in the folder marked Astrophysics of Galaxies and was published on September 12th 2024 with this overlay:

You can find the official accepted version on the arXiv here.

That’s all for now. I will post another update in a week.

https://telescoper.blog/2024/09/14/four-new-publications-at-the-open-journal-of-astrophysics-7/

#arXiv220713241v4 #arXiv240101965v2 #arXiv240405792v2 #arXiv240711968v2 #AstrophysicsOfGalaxies #CosmologyAndNonGalacticAstrophysics #EinsteinBoltzmannEquations #fastRadioBursts #galaxies #galaxyMergers #GalaxyShapes #HighEnergyAstrophysicalPhenomena #HorndeskiGravity #magnetohydrodynamics #MHD #MinkowskiFunctionals #OpenJournalOfAstrophysics #PlasmaPhysics #plasmaTurbulence #TheOpenJournalOfAstrophysics

Notes on #UAP Discussions : How would you introduce a class on "theoretical advances in novel propulsion systems " ?
if you were going to start with early history your candidates are primarily #Antigravity and #Electrostatics but a basic functional approach might start with concepts of mass levitation and associated phenomenologies like #Superconductivity, #Magnetohydrodynamics, #plasmas and #Solitons. Emphasis should be on the fact that there is more than one path to unconventional propulsion

The sun’s corona — its outer atmosphere — is usually impossible to see, since it’s far outshone by the rest of the sun. But during a total solar eclipse, the moon blocks out all but the vibrant, wispy corona. Getting a detailed image of the corona is tough; it’s constantly shifting. For this image, engineer Phil Hart used 5 main cameras, 4 refractors, 2 laptops, and plenty of digital image processing to capture some incredible details of the plasma and hot gases dancing along the sun’s magnetic field lines. You can learn about the awesome effort behind this image — and see more awesome photos from the eclipse — at his site. (Image credit: P. Hart; via APOD)

https://fyfluiddynamics.com/2024/08/the-solar-corona-in-detail/

#flowVisualization #fluidDynamics #fluidsAsArt #magnetohydrodynamics #physics #plasma #science #solarDynamics #solarEclipse #sun

From Earth, we rarely glimpse the violent flows of our home star. Here, a filament erupts from the photosphere creating a coronal mass ejection, captured in ultraviolet wavelengths by the Solar Dynamics Observatory. This particular eruption took place in 2012, and, while it was not aimed at the Earth, it did create auroras here a few days later. Eruptions like these occur as complex interactions between the sun’s hot, ionized plasma and its magnetic fields. Magnetohydrodynamics like these are particularly tough to understand because they combine magnetic physics, chemistry, and flow. (Image credit: NASA/GSFC/SDO; via APOD)

https://fyfluiddynamics.com/2024/07/solar-filament-eruption/

#coronalMassEjection #fluidDynamics #magneticField #magnetohydrodynamics #NASASDO #physics #plasma #science #solarDynamics #sun

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)

https://fyfluiddynamics.com/2024/07/a-shallow-origin-for-the-suns-magnetic-field/

#astrophysics #fluidDynamics #instability #magneticField #magnetohydrodynamics #physics #science #solarDynamics #sun #turbulence

The ESA’s Solar Orbiter captured this beautifully detailed video of our sun‘s corona last September. The Solar Orbiter took this footage from about 43 million kilometers away, a third of the distance between the sun and the Earth. Scattered across the visible surface are fluffy, lace-like features known as coronal moss. Along the curving horizon, gas spires called spicules stretch up to heights of 10,000 kilometers. The video also highlights a “small” eruption of plasma that is nevertheless larger than the entire Earth. We can even see evidence of coronal rain, denser and darker clumps of plasma that gravity pulls back toward the sun. (Video and image credit: ESA; via Colossal)

https://fyfluiddynamics.com/2024/06/the-solar-corona-in-stunning-detail/

#convection #fluidDynamics #magnetohydrodynamics #physics #plasma #science #solarDynamics #sun #turbulence

Ferrofluids are a great platform for exploring liquids and magnetism. Here, researchers trap ferrofluid droplets along an oil-water meniscus and then apply a magnetic field that makes the drops repel one another. The results are crystalline patterns formed from magnetic droplets. For a given patch of drops, increasing the magnetic field’s strength pushes drops further apart. But changing the drops’ size and levels of self-attraction also shifts the patterns. Check out the video to see the crystals in action. (Video and image credit: H. Khattak et al.)

https://fyfluiddynamics.com/2024/06/making-magnetic-crystals-from-ferrofluids/

#2024gosm #ferrofluid #fluidDynamics #magneticField #magnetohydrodynamics #physics #science

A comet‘s tail changes from day-to-day depending on how much material the comet is losing and how strong the solar wind it’s facing is. This image sequence shows Comet 12P/Pons-Brooks over nine days in 2024 from March 6th (top) through March 14th (bottom). The variations in the comet’s appearance are striking; some days show nearly no tail while others have long plumes with swirls of turbulence. It’s a reminder that, even if they appear unchanging in the moment you see one, a comet is in constant flux. (Image credit: Shengyu Li & Shaining; via APOD)

https://fyfluiddynamics.com/2024/05/a-comets-tail/

#comet #flowVisualization #fluidDynamics #magnetohydrodynamics #physics #plumes #science #solarWind #turbulence

This clever image is actually two solar eclipses stacked atop one another. The bottom half of the image shows the sun‘s corona — its wispy, dramatic outer atmosphere — during the a 2017 total solar eclipse, and top half shows a 2023 total solar eclipse. In both, the corona has been unwrapped from around the sun’s circumference and project instead into a rectangle.

The 2017 eclipse took place near the minimum of the sun’s solar cycle and appears relatively tranquil. The 2023 eclipse, in contrast, came near solar cycle’s maximum and shows a far more chaotic and turbulent environment. Notice the bright pink solar prominences dotting the mid-line and the field of shadowy plasma loops above them. (Image credit: P. Ward; via APOD)

https://fyfluiddynamics.com/2024/05/our-suns-corona-unfurled/

#coronalMassEjection #fluidDynamics #magnetohydrodynamics #physics #plasma #science #solarEclipse #sun