Geophysicists detect electron dance deep inside the Earth, with a Twist

Asia's Tech News Daily

Geophysicists detect electron dance deep inside the Earth, with a Twist

Most are aware that electrons are negatively charged particles that surround the nucleus of atoms and whose behaviour governs chemical interactions. However, it is less commonly known that electrons come in two distinct kinds: spin-up and spin-down. And the tendency for pairing between up and down spin electrons, forming “dance partners” with one another, is one of the most important behaviours affecting the electron clouds that control the chemistry of nature.

Under pressures like those deep inside the Earth, the orbits in which the electrons move are squeezed, the “dance floor” changes. Electron pairs are sometimes forced to change their dance pattern and the way that they partner with one another, giving rise to what is termed an “electron spin-pairing crossover” (“spin crossover” is often used as a shorthand expression).

Such a spin-crossover has long been predicted to occur at elevated pressures of the middle mantle (~1500 km deep) in a mineral called “ferro-periclase” that is thought to be the second-most abundant material in Earth’s rocky mantle. Such predictions for a ferropericlase spin-crossover have been broadly confirmed, both by high-pressure laboratory experiments as well as computational models based on quantum mechanics. However, the predicted effects of this spin-crossover escaped seismological detection, leaving deep-Earth researchers to wonder if the predictions were flawed or if conditions in the mantle suppress the seismic expression.

A new research paper published in Nature Communications by an international research team including Earth-Life Science Institute (ELSI) Professor John W. Hernlund (Tokyo Institute of Technology) and ELSI Specially Appointed Assistant Professor Christine Houser proposes a unique seismological signature of this spin crossover in ferropericlase.

The team’s detection method is based on the varying behaviour of the spin crossover for P-waves and S-waves, two distinct kinds of seismic waves that propagate through the Earth. Seismologists use both of these waves (generated by earthquakes and recorded at global seismographic stations) to produce tomographic images of the mantle in a procedure that is roughly analogous to a medical CT scan. The images reveal material that propagates these two kinds of seismic waves faster or slower than the average.

Seismic images of high wave-speed features imaged at mid-mantle depths show that the P-wave signatures of prominent seismically fast features become muted in comparison to their S-wave counterparts. As it turns out, precisely this kind of behaviour is expected for rock containing plausible amounts of ferropericlase at mid-mantle conditions and is caused by a combination of the spin crossover’s induced volume to decrease, as well as its broadening over a wider pressure range at higher temperatures.

Encouraged by this possible connection, the research team hypothesised that if the spin crossover explains this behaviour in fast seismic features in the mid-mantle, then it should also occur for slow features at greater depths owing to the characteristics of the spin transition at high temperatures. When they looked for this signature in slow features, they again found evidence for a weakening of P-wave features relative to S-wave counterparts at the greater depths they predicted.

The research team then had to exclude the possibility that these signals in P-wave and S-wave seismic images were not simply due to resolution artefacts such as differences in the behaviours of these waves and construction of the corresponding images. They used a variety of seismic images produced by different research groups, most of them using different imaging techniques, and then compared the features that all of them agreed upon. This “vote map” method was originally pioneered by lead author Grace Shephard at the University of Oslo. When they calculated and plotted profiles of the abundance of fast and slow S-wave and P-wave features, the muting of features in P-wave models consistent with the spin crossover was prevalent and unmistakable.

When asked which of the pieces of evidence seemed to give the strongest support for the detection of the spin crossover, co-author Christine Houser said that all of the evidence has to be considered together. Houser added that the “relative muting of P-wave signals at two different depths for fast and slow anomalies is difficult to explain away as the result of imaging errors. While not impossible, it would be an unlikely coincidence for models assembled using different data and methods to consistently display the same seismic signals as the spin crossover.”

While detecting the seismic signal of the iron spin crossover reveals regions where oceanic plates rise and sink in the deep mantle, one glaring problem remains the absence of the predicted signal in globally averaged seismic profiles of the Earth’s mantle. Members of the same team previously found that this could not be explained by averaging over the same kinds of materials at different temperatures. Instead, large scale changes in chemical composition may be necessary, such as the presence of regions in the mid-mantle containing rocks that have little ferropericlase (and hence no visible signature of a spin-crossover).

A previous study that several members of this research team were involved in proposed the presence of such features in the mid-mantle, which anchor the pattern of the Earth’s deep mantle convection and persist over billions of years owing to their high strength. They called these “Bridgmanite Enriched Ancient Mantle Structures” or BEAMS (bridgmanite is the most abundant mineral on the Earth and is also thought to be the strongest), and speculated that they might exert a fundamental control on the pattern of tectonic plate motions over Earth’s history.

The spin-crossover detection in the mantle’s fastest and slowest wave speed regions highlights another critical geophysical effect. Fast regions consist of former ocean bedrock diving across the mantle on its journey to the core-mantle boundary. In contrast, slow regions consist of rocks heated by contact with the molten iron core, rising to the surface like a lava lamp. This convection process recycles rocks between the surface and the interior, powering plate tectonics.

Identifying the distinct seismological signature of the spin-crossover in ferropericlase in the mantle shows that building a bridge between materials physics and geophysics is critical to understanding Earth and planetary interiors. The unique seismic signature allows us to determine which parts of the Earth’s deep mantle contain more or less of the mineral ferropericlase, effectively producing 4D geologic maps and revealing Earth’s history across the vast expanse of the deep interior and deep time.

Research Report: “Seismological expression of the iron spin crossover in ferropericlase in the Earth’s lower mantle”

Internet Explorer Channel Network
Asia's Tech News Daily
News Related


Too much heavy metal stops stars producing

Stars are giant factories that produce most of the elements in the Universe – including the elements in us, and in the Earth’s metal deposits. But what stars produce changes ... Read more »

Deciphering conditions around the Sun five million years ago

Using high-resolution data obtained from the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope, Wesleyan University Professor of Astronomy Seth Redfield can show the conditions the Sun encountered traveling ... Read more »

Researchers Observe Massive CME on Distant, Sun-Like Star

EK Draconis illuminates an unimagined picture of how superflares may affect interplanetary space through coronal mass ejections Welcome to the New Year! While Earth celebrated 2022’s arrival with displays of ... Read more »

North Pole solar eclipse excited auroras on the other side of the world

A solar eclipse over the Arctic created changes in auroras in both of Earth’s hemispheres due to connections through the planet’s magnetic field, according to a new study. The new ... Read more »

Increased space missions risk extraterrestrial contamination

The days of the U.S.-Soviet Space Race are over, and the domain of space exploration is expanding daily to include more countries than ever before. With the advent of private ... Read more »

Planet to launch 44 SuperDove satellites on SpaceX's Falcon 9

Planet Labs PBC reports announced that the launch of their Flock 4x, consisting of 44 SuperDove satellites, will take place on Thursday, January 13th on SpaceX’s Falcon 9 Transporter-3 SSO. ... Read more »

Mangata Networks announces funding for satellite edge computing network

Mangata Networks has closed a $33 million Series A round led by US-based venture capital firm Playground Global to continue its mission to transform the way the world interacts with ... Read more »

Advances in Space Transportation Systems Transforming Space Coast

From a seaside perch overlooking the hustle and bustle of ships coming and going at Port Canaveral on Florida’s east coast, Dale Ketcham reflects on decades of history with nostalgia. ... Read more »

Indian Space Agency tests cryogenic engine for its first-ever manned mission

India’s flagship human spaceflight mission, Gaganyaan, has completed the design and testing phases. The Indian Space Research Organisation (ISRO) plans to launch two uncrewed missions ahead of the final mission ... Read more »

Manufacturing revenues for Earth observation to grow to $76.1 billion by 2030

Euroconsult, the leading space consulting and market intelligence firm, has released its eagerly awaited ”Earth Observation Satellite Systems Market” report, providing a sweeping review analysis of the Earth Observation (EO) ... Read more »

NASA's new IXPE mission begins science operations

NASA’s newest X-ray eyes are open and ready for discovery! Having spent just over a month in space, the Imaging X-ray Polarimetry Explorer (IXPE) is working and already zeroing in ... Read more »

Ride into space on Vega-C secured for FLEX and Altius

A contract signed with Arianespace secures the joint launch for two satellites that will further knowledge of our home planet. Scheduled to lift off on a new class of rocket, ... Read more »

The Incredible ASIM: Distant galaxy edition

The Atmosphere-Space Interactions Monitor, or ASIM for short, is a first-of-its-kind complement of instruments on the International Space Station. Dubbed the ‘space storm hunter’, ASIM measures electric events in Earth’s ... Read more »

From dust to planet: how gas giants form

Gas giants are made of a massive solid core surrounded by an even larger mass of helium and hydrogen. But even though these planets are quite common in the Universe, ... Read more »

SDSS-V robots turn their eyes to the sky

After twenty-one years of observers loading heavy aluminum plates night after night, the Sloan Digital Sky Survey (SDSS) is now seeing the cosmos through robotic eyes. Following more than five ... Read more »

Cheops reveals a rugby ball-shaped exoplanet

ESA’s exoplanet mission Cheops has revealed that an exoplanet orbiting its host star within a day has a deformed shape more like that of a rugby ball than a sphere. ... Read more »

Advertising plays key role in satellite TV success, study shows

The pay television market in the United States was dominated by a handful of cable operators until the early 1990s with the entry of satellite TV, which has grown consistently ... Read more »

Elusive atmospheric molecule produced in a lab for the 1st time by UH

The previously elusive methanediol molecule of importance to the organic, atmospheric science and astrochemistry communities has been synthetically produced for the first time by University of Hawai?i at Manoa researchers. ... Read more »

Astroscale U.S. and Orbit Fab sign first on-orbit satellite fuel sale agreement

Orbit Fab, the Gas Stations in Space refueling service provider and Astroscale U.S. Inc., the U.S. subsidiary of Astroscale Holdings Inc. and market leader in securing long-term orbital sustainability, has ... Read more »

ASU instrument captures breathtaking 'first light' images

ASU scientists and engineers building the Europa Thermal Emission Imaging System (E-THEMIS) for NASA’s Europa Clipper passed a major hurdle recently by capturing the first successful test images from this ... Read more »

Astronomers identify potential clue to reinonization of universe

About 400,000 years after the universe was created began a period called “The Epoch of Reionization.” During this time, the once hotter universe began to cool and matter clumped together, ... Read more »

Mini monster black hole could hold clues to giant's growth

The discovery of a supermassive black hole in a relatively small galaxy could help astronomers unravel the mystery surrounding how the very biggest black holes grow. Researchers used NASA’s Chandra ... Read more »

Simulated Image Shows How NASA's Roman Could Expand on Hubble's Deepest View

A team of astrophysicists has created a simulated image that shows how the Nancy Grace Roman Space Telescope could conduct a mega-exposure similar to but far larger than Hubble’s celebrated ... Read more »

Ocean Physics Explain Cyclones on Jupiter

Hurtling around Jupiter and its 79 moons is the Juno spacecraft, a NASA-funded satellite that sends images from the largest planet in our solar system back to researchers on Earth. ... Read more »

Gilmour Space fires up for 2022 with Australia's largest rocket engine test

Rocket engineers at Gilmour Space Technologies have greeted the new year with a successful 110-kilonewton test fire of the most powerful rocket engine ever developed in Australia. The 75-second test ... Read more »

Prestwick Spaceport Files Planning Application Notice

South Ayrshire Council has started the process of submitting a formal planning application for the Prestwick Spaceport development. The Proposal of Application Notice (POAN) is the first step in the ... Read more »

Life could be thriving in the clouds of Venus

by Eric Verbeten for WISC News Is there life on Venus? For more than a century, scientists have pondered this question. Now, there is renewed interest in Venus as a ... Read more »

How the Earth's tilt creates short, cold January days

As the Earth orbits the sun, it spins around an axis – picture a stick going through the Earth, from the North Pole to the South Pole. During the 24 ... Read more »

NASA's newest astronaut class begins training in Houston

NASA swore in 10 new astronaut candidates Monday at Johnson Space Center in Houston — six men and four women — who someday may walk on the moon or Mars. ... Read more »

Shouzhou XIII crew finishes cargo spacecraft, space station docking test

The Shenzhou XIII astronauts in China’s space station core module have completed the manual rendezvous and docking experiment with the Tianzhou 2 cargo craft, the China Manned Space Agency (CMSA) ... Read more »

Take-Two to buy 'Farmville' creator Zynga for $12.7 bn

Video game publisher Take-Two announced Monday it reached a deal to acquire “Farmville” creator Zynga for $12.7 billion, in a major mobile gaming push by the maker of “Grand Theft ... Read more »

Hubble sees cosmic clues in a galactic duo

This spectacular image from the NASA/ESA Hubble Space Telescope captures the spiral galaxy NGC 105, which lies roughly 215 million light-years away in the constellation Pisces. While it looks like ... Read more »

Eccentric exoplanet discovered

Led by the University of Bern, an international research team has discovered a sub-Neptune exoplanet orbiting a red dwarf star. The discovery was also made thanks to observations performed by ... Read more »

Real-time alert system heralds new era in fast radio burst research

McGill University scientists have developed a new system for sharing the enormous amount of data being generated by the CHIME radio telescope in its search for fast radio bursts (FRBs), ... Read more »

NASA to host coverage for Webb Telescope's final unfolding

NASA will provide live coverage and host a media briefing Saturday, Jan. 8, for the conclusion of the James Webb Space Telescope’s major spacecraft deployments. Beginning no earlier than 9 ... Read more »

Loft Orbital extends production agreement with LeoStella

Loft Orbital Solutions, Inc. (Loft Orbital), a leading space infrastructure-as-a-service provider, and LeoStella, Inc., a specialized satellite constellation design and manufacturing company, have extended their production agreement to secure multiple ... Read more »

Asteroid with a refreshed surface

How did our Solar System form and evolve? Various models for the creation of our system of planets have been proposed, but the planets themselves provide unfortunately little information as ... Read more »

Arianespace consolidates leadership in commercial market with 15 Ariane, Soyuz and Vega launches in 2021

Arianespace confirmed its strong performance in 2021, with 15 successful launches – five more than in 2020 – and 305 satellites sent into orbit using its three launchers, Ariane, Soyuz ... Read more »

Debris from failed Russian rocket falls into sea near French Polynesia

The upper stage of a failed Russian Angara A5 rocket plummeted uncontrolled to Earth, crashing into open sea near French Polynesia. The U.S. 18th Space Control Squadron confirmed the 4 ... Read more »

Metaverse gets touch of reality at CES

A jacket equipped with sensors that let wearers feel hugs or even punches in virtual reality was among the innovations giving the metaverse a more realistic edge at the Consumer ... Read more »
On you will find lots of free English exam practice materials to help you improve your English skills: grammar, listening, reading, writing, ielts, toeic