Category: Breaking News

An Overlooked Piece Of The Solar Dynamo Puzzle

 

A previously unobserved mechanism is at work in the Sun’s rotating plasma: a magnetic instability, which scientists had thought was physically impossible under these conditions. The effect might even play a crucial role in the formation of the Sun’s magnetic field, say researchers from Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the University of Leeds and the Leibniz Institute for Astrophysics Potsdam (AIP) in the journal Physical Review Fluids.

Just like an enormous dynamo, the sun’s magnetic field is generated by electric currents. In order to better understand this self-reinforcing mechanism, researchers must elucidate the processes and flows in the solar plasma. Differing rotation speeds in different regions and complex flows in the sun’s interior combine to generate the magnetic field. In the process, unusual magnetic effects can occur — like this newly discovered magnetic instability.

Researchers have coined the term “Super HMRI” for this recently observed special case of magnetorotational instability (MRI). It is a magnetic mechanism that causes the rotating, electroconductive fluids and gases in a magnetic field to become unstable. What is special about this case is that the Super HMRI requires exactly the same conditions that prevail in the plasma close to the solar equator — the place where astrophysicists observe the most sunspots and, thus, the Sun’s greatest magnetic activity. So far, however, this instability in the Sun had gone completely unnoticed and is not yet integrated in models of the solar dynamo.

It is, nonetheless, known that magnetic instabilities are crucially involved in many processes in the universe. Stars and planets, for example, are generated by large rotating disks of dust and gas. In the absence of a magnetic field, this process would be inexplicable. Magnetic instabilities cause turbulence in the flows within the disks and thus enable the mass to agglomerate into a central object. Like a rubber band, the magnetic field connects neighboring layers that rotate at different speeds. It accelerates the slow particles of matter at the edges and slows down the fast ones on the inside. There the centrifugal force is not strong enough and the matter collapses into the center. Near the solar equator it behaves precisely the other way around. The inner layers move more slowly than the outer ones. Up to now, experts had considered this kind of flow profile to be physically extremely stable.

The researchers at HZDR, the University of Leeds and AIP still decided to investigate it more thoroughly. In the case of a circular magnetic field, they had already calculated that even when fluids and gases were rotating faster on the outside, magnetic instability could occur. However, only under unrealistic conditions: the rotational speed would have to increase too strongly towards the outer edge.

Trying another approach, they now based their investigations on a helical magnetic field. “We didn’t have any great expectations, but then we were in for a genuine surprise,” HZDR’s Dr. Frank Stefani remembers — because the magnetic instability can already occur when the speed between the rotating layers of plasma only increases slightly — which happens in the region of the Sun closest to the equator.

“This new instability could play an important role in generating the sun’s magnetic field,” Stefani estimates. “But in order to confirm it we first need to do further numerically complicated calculations.” Prof. Günther Rüdiger of AIP adds, “Astrophysicists and climate researchers still hope to better understand the cycle of sunspots. Perhaps the ‘Super HMRI’ we have now found will take us a decisive step forward. We’ll check it out.”

With its various specialisms in magnetohydrodynamics and astrophysics, the interdisciplinary research team has been investigating magnetic instabilities — in the lab, on paper and with the aid of sophisticated simulations — for more than 15 years. The scientists want to improve physical models, understand cosmic magnetic fields and develop innovative liquid metal batteries. Thanks to close cooperation, in 2006, they managed to experimentally prove the theory of magnetorotational instability for the first time. They are now planning the test for the special form they have predicted in theory: In a large-scale experiment that is currently being set up in the DRESDYN project at HZDR, they want to study this magnetic instability in the lab.

2019 Nobel Prize In Physics: Evolution Of The Universe And Discovery Of Exoplanet Orbiting Solar-Type Star

 

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2019 “for contributions to our understanding of the evolution of the universe and Earth’s place in the cosmos” with one half to James Peebles of Princeton University, USA, “for theoretical discoveries in physical cosmology” and the other half jointly to Michel Mayor of the University of Geneva, Switzerland, and Didier Queloz of the University of Geneva, Switzerland, and the University of Cambridge, UK, “for the discovery of an exoplanet orbiting a solar-type star.”

New perspectives on our place in the universe

This year’s Nobel Prize in Physics rewards new understanding of the universe’s structure and history, and the first discovery of a planet orbiting a solar-type star outside our solar system.

James Peebles’ insights into physical cosmology have enriched the entire field of research and laid a foundation for the transformation of cosmology over the last fifty years, from speculation to science. His theoretical framework, developed since the mid-1960s, is the basis of our contemporary ideas about the universe.

The Big Bang model describes the universe from its very first moments, almost 14 billion years ago, when it was extremely hot and dense. Since then, the universe has been expanding, becoming larger and colder. Barely 400,000 years after the Big Bang, the universe became transparent and light rays were able to travel through space. Even today, this ancient radiation is all around us and, coded into it, many of the universe’s secrets are hiding. Using his theoretical tools and calculations, James Peebles was able to interpret these traces from the infancy of the universe and discover new physical processes.

The results showed us a universe in which just five per cent of its content is known, the matter which constitutes stars, planets, trees — and us. The rest, 95 per cent, is unknown dark matter and dark energy. This is a mystery and a challenge to modern physics.

In October 1995, Michel Mayor and Didier Queloz announced the first discovery of a planet outside our solar system, an exoplanet, orbiting a solar-type star in our home galaxy, the Milky Way. At the Haute-Provence Observatory in southern France, using custom-made instruments, they were able to see planet 51 Pegasi b, a gaseous ball comparable with the solar system’s biggest gas giant, Jupiter.

This discovery started a revolution in astronomy and over 4,000 exoplanets have since been found in the Milky Way. Strange new worlds are still being discovered, with an incredible wealth of sizes, forms and orbits. They challenge our preconceived ideas about planetary systems and are forcing scientists to revise their theories of the physical processes behind the origins of planets. With numerous projects planned to start searching for exoplanets, we may eventually find an answer to the eternal question of whether other life is out there.

This year’s Laureates have transformed our ideas about the cosmos. While James Peebles’ theoretical discoveries contributed to our understanding of how the universe evolved after the Big Bang, Michel Mayor and Didier Queloz explored our cosmic neighbourhoods on the hunt for unknown planets. Their discoveries have forever changed our conceptions of the world.

James Peebles, born 1935 in Winnipeg, Canada. Ph.D. 1962 from Princeton University, USA. Albert Einstein Professor of Science at Princeton University, USA.

Michel Mayor, born 1942 in Lausanne, Switzerland. Ph.D. 1971 from University of Geneva, Switzerland. Professor at University of Geneva, Switzerland.

Didier Queloz, born 1966. Ph.D. 1995 from University of Geneva, Switzerland. Professor at University of Geneva, Switzerland and University of Cambridge, UK.

Prize amount: 9 million Swedish krona, with one half to James Peebles and the other half jointly to Michel Mayor and Didier Queloz

Putting The ‘Bang’ In The Big Bang

 

As the Big Bang theory goes, somewhere around 13.8 billion years ago the universe exploded into being, as an infinitely small, compact fireball of matter that cooled as it expanded, triggering reactions that cooked up the first stars and galaxies, and all the forms of matter that we see (and are) today.

Just before the Big Bang launched the universe onto its ever-expanding course, physicists believe, there was another, more explosive phase of the early universe at play: cosmic inflation, which lasted less than a trillionth of a second. During this period, matter — a cold, homogeneous goop — inflated exponentially quickly before processes of the Big Bang took over to more slowly expand and diversify the infant universe.

Recent observations have independently supported theories for both the Big Bang and cosmic inflation. But the two processes are so radically different from each other that scientists have struggled to conceive of how one followed the other.

Now physicists at MIT, Kenyon College, and elsewhere have simulated in detail an intermediary phase of the early universe that may have bridged cosmic inflation with the Big Bang. This phase, known as “reheating,” occurred at the end of cosmic inflation and involved processes that wrestled inflation’s cold, uniform matter into the ultrahot, complex soup that was in place at the start of the Big Bang.

“The postinflation reheating period sets up the conditions for the Big Bang, and in some sense puts the ‘bang’ in the Big Bang,” says David Kaiser, the Germeshausen Professor of the History of Science and professor of physics at MIT. “It’s this bridge period where all hell breaks loose and matter behaves in anything but a simple way.”

Kaiser and his colleagues simulated in detail how multiple forms of matter would have interacted during this chaotic period at the end of inflation. Their simulations show that the extreme energy that drove inflation could have been redistributed just as quickly, within an even smaller fraction of a second, and in a way that produced conditions that would have been required for the start of the Big Bang.

The team found this extreme transformation would have been even faster and more efficient if quantum effects modified the way that matter responded to gravity at very high energies, deviating from the way Einstein’s theory of general relativity predicts matter and gravity should interact.

“This enables us to tell an unbroken story, from inflation to the postinflation period, to the Big Bang and beyond,” Kaiser says. “We can trace a continuous set of processes, all with known physics, to say this is one plausible way in which the universe came to look the way we see it today.”

The team’s results appear today in Physical Review Letters. Kaiser’s co-authors are lead author Rachel Nguyen, and John T. Giblin, both of Kenyon College, and former MIT graduate student Evangelos Sfakianakis and Jorinde van de Vis, both of Leiden University in the Netherlands.

“In sync with itself”

The theory of cosmic inflation, first proposed in the 1980s by MIT’s Alan Guth, the V.F. Weisskopf Professor of Physics, predicts that the universe began as an extremely small speck of matter, possibly about a hundred-billionth the size of a proton. This speck was filled with ultra-high-energy matter, so energetic that the pressures within generated a repulsive gravitational force — the driving force behind inflation. Like a spark to a fuse, this gravitational force exploded the infant universe outward, at an ever-faster rate, inflating it to nearly an octillion times its original size (that’s the number 1 followed by 26 zeroes), in less than a trillionth of a second.

Kaiser and his colleagues attempted to work out what the earliest phases of reheating — that bridge interval at the end of cosmic inflation and just before the Big Bang — might have looked like.

“The earliest phases of reheating should be marked by resonances. One form of high-energy matter dominates, and it’s shaking back and forth in sync with itself across large expanses of space, leading to explosive production of new particles,” Kaiser says. “That behavior won’t last forever, and once it starts transferring energy to a second form of matter, its own swings will get more choppy and uneven across space. We wanted to measure how long it would take for that resonant effect to break up, and for the produced particles to scatter off each other and come to some sort of thermal equilibrium, reminiscent of Big Bang conditions.”

The team’s computer simulations represent a large lattice onto which they mapped multiple forms of matter and tracked how their energy and distribution changed in space and over time as the scientists varied certain conditions. The simulation’s initial conditions were based on a particular inflationary model — a set of predictions for how the early universe’s distribution of matter may have behaved during cosmic inflation.

The scientists chose this particular model of inflation over others because its predictions closely match high-precision measurements of the cosmic microwave background — a remnant glow of radiation emitted just 380,000 years after the Big Bang, which is thought to contain traces of the inflationary period.

A universal tweak

The simulation tracked the behavior of two types of matter that may have been dominant during inflation, very similar to a type of particle, the Higgs boson, that was recently observed in other experiments.

Before running their simulations, the team added a slight “tweak” to the model’s description of gravity. While ordinary matter that we see today responds to gravity just as Einstein predicted in his theory of general relativity, matter at much higher energies, such as what’s thought to have existed during cosmic inflation, should behave slightly differently, interacting with gravity in ways that are modified by quantum mechanics, or interactions at the atomic scale.

In Einstein’s theory of general relativity, the strength of gravity is represented as a constant, with what physicists refer to as a minimal coupling, meaning that, no matter the energy of a particular particle, it will respond to gravitational effects with a strength set by a universal constant.

However, at the very high energies that are predicted in cosmic inflation, matter interacts with gravity in a slightly more complicated way. Quantum-mechanical effects predict that the strength of gravity can vary in space and time when interacting with ultra-high-energy matter — a phenomenon known as nonminimal coupling.

Kaiser and his colleagues incorporated a nonminimal coupling term to their inflationary model and observed how the distribution of matter and energy changed as they turned this quantum effect up or down.

In the end they found that the stronger the quantum-modified gravitational effect was in affecting matter, the faster the universe transitioned from the cold, homogeneous matter in inflation to the much hotter, diverse forms of matter that are characteristic of the Big Bang.

By tuning this quantum effect, they could make this crucial transition take place over 2 to 3 “e-folds,” referring to the amount of time it takes for the universe to (roughly) triple in size. In this case, they managed to simulate the reheating phase within the time it takes for the universe to triple in size two to three times. By comparison, inflation itself took place over about 60 e-folds.

“Reheating was an insane time, when everything went haywire,” Kaiser says. “We show that matter was interacting so strongly at that time that it could relax correspondingly quickly as well, beautifully setting the stage for the Big Bang. We didn’t know that to be the case, but that’s what’s emerging from these simulations, all with known physics. That’s what’s exciting for us.”

This research was supported, in part, by the U.S. Department of Energy and the National Science Foundation.

ESO Telescope Reveals What Could Be The Smallest Dwarf Planet Yet In The Solar System

 

Astronomers using ESO’s SPHERE instrument at the Very Large Telescope (VLT) have revealed that the asteroid Hygiea could be classified as a dwarf planet. The object is the fourth largest in the asteroid belt after Ceres, Vesta and Pallas. For the first time, astronomers have observed Hygiea in sufficiently high resolution to study its surface and determine its shape and size. They found that Hygiea is spherical, potentially taking the crown from Ceres as the smallest dwarf planet in the Solar System.

 

As an object in the main asteroid belt, Hygiea satisfies right away three of the four requirements to be classified as a dwarf planet: it orbits around the Sun, it is not a moon and, unlike a planet, it has not cleared the neighbourhood around its orbit. The final requirement is that it has enough mass for its own gravity to pull it into a roughly spherical shape. This is what VLT observations have now revealed about Hygiea.

“Thanks to the unique capability of the SPHERE instrument on the VLT, which is one of the most powerful imaging systems in the world, we could resolve Hygiea’s shape, which turns out to be nearly spherical,” says lead researcher Pierre Vernazza from the Laboratoire d’Astrophysique de Marseille in France. “Thanks to these images, Hygiea may be reclassified as a dwarf planet, so far the smallest in the Solar System.”

The team also used the SPHERE observations to constrain Hygiea’s size, putting its diameter at just over 430 km. Pluto, the most famous of dwarf planets, has a diameter close to 2400 km, while Ceres is close to 950 km in size.

Surprisingly, the observations also revealed that Hygiea lacks the very large impact crater that scientists expected to see on its surface, the team report in the study published today in Nature Astronomy. Hygiea is the main member of one of the largest asteroid families, with close to 7000 members that all originated from the same parent body. Astronomers expected the event that led to the formation of this numerous family to have left a large, deep mark on Hygiea.

“This result came as a real surprise as we were expecting the presence of a large impact basin, as is the case on Vesta,” says Vernazza. Although the astronomers observed Hygiea’s surface with a 95% coverage, they could only identify two unambiguous craters. “Neither of these two craters could have been caused by the impact that originated the Hygiea family of asteroids whose volume is comparable to that of a 100 km-sized object. They are too small,” explains study co-author Miroslav Bro? of the Astronomical Institute of Charles University in Prague, Czech Republic.

The team decided to investigate further. Using numerical simulations, they deduced that Hygiea’s spherical shape and large family of asteroids are likely the result of a major head-on collision with a large projectile of diameter between 75 and 150 km. Their simulations show this violent impact, thought to have occurred about 2 billion years ago, completely shattered the parent body. Once the left-over pieces reassembled, they gave Hygiea its round shape and thousands of companion asteroids. “Such a collision between two large bodies in the asteroid belt is unique in the last 3-4 billion years,” says Pavel Ševe?ek, a PhD student at the Astronomical Institute of Charles University who also participated in the study.

Studying asteroids in detail has been possible thanks not only to advances in numerical computation, but also to more powerful telescopes. “Thanks to the VLT and the new generation adaptive-optics instrument SPHERE, we are now imaging main belt asteroids with unprecedented resolution, closing the gap between Earth-based and interplanetary mission observations,” Vernazza concludes.

Category 4 Hurricane Lorenzo is the Most Intense Hurricane So Far East in the Atlantic Ocean on Record

 

Hurricane Lorenzo became the most intense hurricane so far east in the Atlantic Ocean on record Thursday night, and poses a danger to the Azores next week.

Lorenzo rapidly intensified into a Category 4 hurricane Thursday, with maximum winds estimated at 145 mph.

According to Dr. Phil Klotzbach, a tropical scientist at Colorado State University, Lorenzo became the most intense hurricane east of 45 degrees West longitude in the historical record.

Lorenzo is even a bigger outlier when considering only those Category 4 hurricanes from Sept. 26 through the end of the season, as pointed out by Richard Dixon, a meteorologist at CatInsight and Michael Lowry, an atmospheric scientist at FEMA.

Even in the heart of hurricane season, tropical waves moving off the coast of western Africa usually take some time to mushroom into intense hurricanes.

This is often due to intrusions of dry air, known as Saharan air layers, moving off Africa’s Sahara Desert. Fledgling tropical disturbances need warm, moist air to intensify, so battling these intrusions can prevent intensification or even spell doom in the eastern Atlantic Ocean.

In Lorenzo’s case, that wasn’t a big problem.

A lack of shearing winds, typically warm ocean water and moist air allowed Lorenzo to rapidly intensify so far east.

Lorenzo strengthened from a tropical storm on Tuesday into a hurricane on Wednesday, before reaching Category 4 hurricane strength by late Thursday morning.

Azores Threat
The storm is no immediate threat to land, but it is forecast to pass near the Azores Tuesday night or early Wednesday as a weaker, but still formidable hurricane.

The National Hurricane Center mentioned Lorenzo’s wind field is large, increasing the chances it may impact the group of Portuguese islands about 900 miles west of Portugal.

NHC forecaster Eric Blake tweeted Thursday its size resembled that of a super typhoon in the western Pacific Ocean than an eastern Atlantic hurricane.

According to NOAA’s historical database, only seven Category 2 or stronger hurricanes have tracked within 200 nautical miles of the Azores, in records dating to the mid-19th century.

Ophelia passed south the Azores as a Category 3 hurricane in mid-October 2017, but produced tropical storm-force winds, downing a few trees and triggering some minor flooding, according to the NHC’s final report.

A September 1926 Category 2 hurricane with estimated winds of 105 mph tracked over the island of São Miguel.

As meteorologist Yaakov Cantor mentioned Thursday, there have been a number of strange eastern Atlantic hurricanes and tropical storms in recent years, including Leslie almost making it to Portugal as a hurricane in 2018 and a bizarre January strike from Hurricane Alex in the Azores.

Hidden World Of Undersea Volcanoes And Lava Flows Discovered Off Italian Coast

 

Hidden beneath the waves of the Tyrrhenian Sea near southwestern Italy lies a newfound volcanic mosaic dotted with geothermal chimneys and flat-topped seamounts.

This complex is new to both science and the planet, geologically speaking; it’s only about 780,000 years old. Scientists aren’t particularly surprised to find volcanism in the region, which is home to active volcanoes like Mount Vesuvius and Mount Etna. But the new complex is unusual because it was created by a rare kind of fault, said study leader Fabrizio Pepe, a geophysicist at the University of Palermo, in Italy.

“This is a very complex area,” Pepe told Live Science.

Restless region

The western Mediterranean is seismically restless because of the collision of three tectonic plates: the African, the Eurasian and the Anatolian. Making matters more complex is a small chunk of crust called the Adriatic-Ionian microplate, which broke off of the African Plate more than 65 million years ago and is now being pushed under the larger Eurasian Plate in a process called subduction. Mount Vesuvius is one of the volcanoes created by subduction.

Previously, scientists discovered a series of undersea volcanic arcs created by this tectonic unrest, starting near the Sardinian coast, with increasingly younger arcs southward and eastward. These arcs were like an arrow pointing ever farther eastward, prompting Pepe and his colleagues to search for an even younger arc about 9 miles (15 kilometers) off the coast of Calabria, called the “toe” of the “boot” of Italy.

There, based on seafloor mapping, seismic data and magnetic anomalies, the researchers found a 772-square-mile (2,000 square km) region of lava flows, volcanic mountains and hydrothermal chimneys; vents in the seafloor allow hot minerals to spew out and form chimney-like structures. They dubbed the new area the Diamante‐Enotrio‐Ovidio Volcanic‐Intrusive Complex, after three flat-topped seamounts (underwater mountains formed by extinct volcanoes) that dominate the seafloor.

STEP by step
Those fractures are what allowed magma to rise to the surface at the Diamonte-Enotrio-Ovidio complex, creating an undersea landscape of lava flows and mountainous volcanoes. These volcanic seamounts are now plateaus because they protruded from the ocean when the sea level was lower, and they eroded into their present, flat-topped shape, Pepe said.

The volcanic complex is inactive, but there are small intrusions of lava in some parts of the seafloor there, the researchers reported July 6 in the journal Tectonics. However, the area could become active in the future, Pepe said, and active volcanism is ongoing on the eastern side of the Tyrrhenian Sea. The researchers are working to build a volcanic risk map of the complex to better understand if it could endanger human life or property. They are also investigating the possibility of tapping the complex to produce geothermal energy.

Strong Earthquake Strikes Indonesia, Killing At Least 20 People

 

At least 20 people have been killed in a magnitude 6.5 earthquake on one of Indonesia’s least populated islands.

Graphic shows large earthquake logo over broken earth and Richter scale reading

The quake hit at 6:46 a.m. local time Thursday about 20.5 miles northeast of Ambon in Indonesia’s Maluku province, the U.S. Geological Survey said.

Indonesia’s disaster mitigation agency said dozens of homes, a number of buildings and other public facilities were damaged, including a major bridge in Ambon, Reuters reported.

A teacher was killed when parts of a building at an Islamic university collapsed, according to The Associated Press.

“He was just getting out of a car and entering a door and the collapsing rubble fell onto him,” Benny Bugis, a cameraman who works for Reuters, said. He also said two people were injured.

Agus Wibowo, a spokesman for the disaster mitigation agency, said at least 19 others were killed and about 100 were injured. He said more than 2,000 people took refuge in various shelters.

Rahmat Triyono, head of the earthquake and tsunami division at Indonesia’s Meteorology, Climatology and Geophysical Agency, told the AFP news agency the earthquake did not have the potential to cause a tsunami. Still people along the coast fled to higher ground.

“The tremor was so strong, causing us to pour into the streets,” said Musa, an Ambon resident who uses a single name.

Maluku is one of Indonesia’s least populous provinces with a population of about 1.7 million people.

The earthquake Thursday came two days ahead of the first anniversary of a magnitude 7.5 earthquake in Palu on Sulawesi island that killed more than 4,000 people.

Indonesia sits on the seismically active Pacific Ring of Fire and often experiences deadly earthquakes and tsunamis.

In 2004, a powerful Indian Ocean quake and tsunami killed 230,000 people in a dozen countries, most of them in Indonesia.