LOFAR Radio Telescope Reveals Secrets Of Solar Storms

An international team of scientists led by a researcher from Trinity College Dublin and University of Helsinki announced a major discovery on the very nature of solar storms in the journal Nature Astronomy.

The team showed that solar storms can accelerate particles simultaneously in several locations by combining data from the Low Frequency Array, LOFAR, with images from NASA, NOAA and ESA spacecraft.

The sun is the closest star to Earth, and like many stars, it is far from quiet. Sunspots many times the size of Earth can appear on its surface and store enormous reservoirs of energy. And it is within these regions that huge explosions called solar storms occur. Solar storms are spectacular eruptions of billions of tonnes of hot gas traveling at millions of kilometres an hour. The Nature Astronomy paper reports on a particularly large solar storm that occured on September 10, 2017, soon after the LOFAR station in Ireland came online.

How to predict space weather

“Our results are very exciting, as they give us an amazingly detailed insight into how solar storms propagate away from the sun and where they accelerate fast particles with speeds close to the speed of light,” says Dr. Diana Morosan, the lead author on the publication, and affiliated with Trinity College Dublin and the University of Helsinki.

These results may in the future help researchers to produce more accurate forecasts of solar radio bursts and determine how solar storms impact the Earth—they can produce beautiful displays of the aurora, but they can also cause problems with communication and navigation systems and power grids. Society is now even more dependent on technology, and solar storms have the potential to cause significant effects on their performance.

In 1859, the largest solar storm ever observed – the so-called Carrington Event – occurred. Within hours, it generated displays of aurora as far south as Italy and Cuba and caused interruptions in early telegraph systems in Europe and the U.S.

During a 2003 event, transformers in South Africa were damaged, and Swedish air traffic control systems were closed down in 2015 for more than an hour due to effects associated with a solar storm. More than 50 satellites reported problems. More recently, emergency response communications were interrupted during hurricane season in September 2017 in the Caribbean.

“We used data from the Low Frequency Array, LOFAR, together with images from NASA, NOAA and ESA spacecraft to show where solar storms accelerate fast particles,” says Morosan.

Spacecraft Measurements Reveal Mechanism Of Solar Wind Heating

Queen Mary University of London has led a study which describes the first direct measurement of how energy is transferred from the chaotic electromagnetic fields in space to the particles that make up the solar wind, leading to the heating of interplanetary space.

The study, published in Nature Communications and carried out with University of Arizona and the University of Iowa, shows that a process known as Landau damping is responsible for transferring energy from the electromagnetic plasma turbulence in space to electrons in the solar wind, causing their energisation.

This process, named after the Nobel-prize winning physicist Lev Landau (1908-1968), occurs when a wave travels through a plasma and the plasma particles that are travelling at a similar speed absorb this energy, leading to a reduction of energy (damping) of the wave.

Although this process had been measured in some simple situations previously, it was not known whether it would still operate in the highly turbulent and complex plasmas occurring naturally in space, or whether there would be a different process entirely.

All across the universe, matter is in an energised plasma state at far higher temperatures than expected. For example, the solar corona is hundreds of times hotter than the surface of the Sun, a mystery which scientists are still trying to understand.

It is also vital to understand the heating of many other astrophysical plasmas, such as the interstellar medium and the disks of plasma surrounding black holes, in order to explain some of the extreme behaviour displayed in these environments.

Being able to make direct measurements of the plasma energisation mechanisms in action in the solar wind (as shown in this paper for the first time) will help scientists to understand numerous open questions, such as these, about the universe.

The researchers discovered this using new high-resolution measurements from NASA’s Magnetospheric Multi-Scale (MMS) spacecraft (recently launched in 2015), together with a newly-developed data analysis technique (the field-particle correlation technique).

The solar wind is the stream of charged particles (i.e., plasma) that comes from the Sun and fills our entire solar system, and the MMS spacecraft are located in the solar wind measuring the fields and particles within it as it streams past.

Lead author Dr Christopher Chen, from Queen Mary University of London, said: “Plasma is by far the most abundant form of visible matter in the universe, and is often in a highly dynamic and apparently chaotic state known as turbulence. This turbulence transfers energy to the particles in the plasma leading to heating and energisation, making turbulence and the associated heating very widespread phenomena in nature.

“In this study, we made the first direct measurement of the processes involved in turbulent heating in a naturally occurring astrophysical plasma. We also verified the new analysis technique as a tool that can be used to probe plasma energisation and that can be used in a range of follow-up studies on different aspects of plasma behaviour.”

University of Iowa’s Professor Greg Howes, who co-devised this new analysis technique, said: “In the process of Landau damping, the electric field associated with waves moving through the plasma can accelerate electrons moving with just the right speed along with the wave, analogous to a surfer catching a wave. This first successful observational application of the field-particle correlation technique demonstrates its promise to answer long-standing, fundamental questions about the behavior and evolution of space plasmas, such as the heating of the solar corona.”

This paper also paves the way for the technique to be used on future missions to other areas of the solar system, such as the NASA Parker Solar Probe (launched in 2018) which is beginning to explore the solar corona and plasma environment near the Sun for the first time.

Gravitational Waves Will Settle Cosmic Conundrum

Measurements of gravitational waves from approximately 50 binary neutron stars over the next decade will definitively resolve an intense debate about how quickly our universe is expanding, according to findings from an international team that includes University College London (UCL) and Flatiron Institute cosmologists.

The cosmos has been expanding for 13.8 billion years. Its present rate of expansion, known as “the Hubble constant,” gives the time elapsed since the Big Bang.

However, the two best methods used to measure the Hubble constant have conflicting results, which suggests that our understanding of the structure and history of the universe — the “standard cosmological model” — may be incorrect.

The study, published today in Physical Review Letters, shows how new independent data from gravitational waves emitted by binary neutron stars called “standard sirens” will break the deadlock between the conflicting measurements once and for all.

“We’ve calculated that by observing 50 binary neutron stars over the next decade, we will have sufficient gravitational wave data to independently determine the best measurement of the Hubble constant,” said lead author Dr. Stephen Feeney of the Center for Computational Astrophysics at the Flatiron Institute in New York City. “We should be able to detect enough mergers to answer this question within five to 10 years.”

The Hubble constant, the product of work by Edwin Hubble and Georges Lemaître in the 1920s, is one of the most important numbers in cosmology. The constant “is essential for estimating the curvature of space and the age of the universe, as well as exploring its fate,” said study co-author UCL Professor of Physics & Astronomy Hiranya Peiris.

“We can measure the Hubble constant by using two methods — one observing Cepheid stars and supernovae in the local universe, and a second using measurements of cosmic background radiation from the early universe — but these methods don’t give the same values, which means our standard cosmological model might be flawed.”

Feeney, Peiris and colleagues developed a universally applicable technique that calculates how gravitational wave data will resolve the issue.

Gravitational waves are emitted when binary neutron stars spiral toward each other before colliding in a bright flash of light that can be detected by telescopes. UCL researchers were involved in detecting the first light from a gravitational wave event in August 2017.

Binary neutron star events are rare, but they are invaluable in providing another route to track how the universe is expanding. The gravitational waves they emit cause ripples in space-time that can be detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo experiments, giving a precise measurement of the system’s distance from Earth.

By additionally detecting the light from the accompanying explosion, astronomers can determine the system’s velocity, and hence calculate the Hubble constant using Hubble’s law.

For this study, the researchers modelled how many such observations would be needed to resolve the issue of measuring the Hubble constant accurately.

“This in turn will lead to the most accurate picture of how the universe is expanding and help us improve the standard cosmological model,” concluded Professor Peiris.

The study involved researchers from the Flatiron Institute (USA), UCL, Stockholm University, Radboud University (The Netherlands), Imperial College London, and the University of Chicago. UCL’s contribution was generously funded by the European Research Council.

Quarrying Of Stonehenge ‘Bluestones’ Dated To 3000 BC

Excavations at two quarries in Wales, known to be the source of the Stonehenge ‘bluestones’, provide new evidence of megalith quarrying 5,000 years ago, according to a new UCL-led study.

Geologists have long known that 42 of Stonehenge’s smaller stones, known as ‘bluestones’, came from the Preseli hills in Pembrokeshire, west Wales. Now a new study published in Antiquity pinpoints the exact locations of two of these quarries and reveals when and how the stones were quarried.

The discovery has been made by a team of archaeologists and geologists from UCL, Bournemouth University, University of Southampton, University of the Highlands and Islands and National Museum of Wales, which have been investigating the sites for eight years.

Professor Mike Parker Pearson (UCL Archaeology) and leader of the team, said: “What’s really exciting about these discoveries is that they take us a step closer to unlocking Stonehenge’s greatest mystery — why its stones came from so far away.”

“Every other Neolithic monument in Europe was built of megaliths brought from no more than 10 miles away.

We’re now looking to find out just what was so special about the Preseli hills 5,000 years ago, and whether there were any important stone circles here, built before the bluestones were moved to Stonehenge.”

The largest quarry was found almost 180 miles away from Stonehenge on the outcrop of Carn Goedog, on the north slope of the Preseli hills.

“This was the dominant source of Stonehenge’s spotted dolerite, so-called because it has white spots in the igneous blue rock. At least five of Stonehenge’s bluestones, and probably more, came from Carn Goedog,” said geologist Dr Richard Bevins (National Museum of Wales).

In the valley below Carn Goedog, another outcrop at Craig Rhos-y-felin was identified by Dr Bevins and fellow geologist Dr Rob Ixer (UCL Archaeology) as the source of one of the types of rhyolite — another type of igneous rock — found at Stonehenge.

According to the new study, the bluestone outcrops are formed of natural, vertical pillars. These could be eased off the rock face by opening up the vertical joints between each pillar. Unlike stone quarries in ancient Egypt, where obelisks were carved out of the solid rock, the Welsh quarries were easier to exploit.

Neolithic quarry workers needed only to insert wedges into the ready-made joints between pillars, then lower each pillar to the foot of the outcrop.

Although most of their equipment is likely to have consisted of perishable ropes and wooden wedges, mallets and levers, they left behind other tools such as hammer stones and stone wedges.

“The stone wedges are made of imported mudstone, much softer than the hard dolerite pillars. An engineering colleague has suggested that hammering in a hard wedge could have created stress fractures, causing the thin pillars to crack. Using a soft wedge means that, if anything were to break, it would be the wedge and not the pillar,” said Professor Parker Pearson.

Archaeological excavations at the foot of both outcrops uncovered the remains of human-made stone and earth platforms, with each platform’s outer edge terminating in a vertical drop of about a metre.

“Bluestone pillars could be eased down onto this platform, which acted as a loading bay for lowering them onto wooden sledges before dragging them away,” said Professor Colin Richards (University of the Highlands and Islands), who has excavated Britain’s only other identified megalith quarry in the Orkney islands, off the north coast of Scotland.

An important aim of Professor Parker Pearson’s team was to date megalith-quarrying at the two outcrops. In the soft sediment of a hollowed-out track leading from the loading bay at Craig Rhos-y-felin, and on the artificial platform at Carn Goedog, the team recovered pieces of charcoal dating to around 3000 BC.

The team now thinks that Stonehenge was initially a circle of rough, unworked bluestone pillars set in pits known as the Aubrey Holes, near Stonehenge, and that the sarsens (sandstone blocks) were added some 500 years later.

The new discoveries also cast doubt on a popular theory that the bluestones were transported by sea to Stonehenge.

“Some people think that the bluestones were taken southwards to Milford Haven and placed on rafts or slung between boats and then paddled up the Bristol Channel and along the Bristol Avon towards Salisbury Plain. But these quarries are on the north side of the Preseli hills so the megaliths could have simply gone overland all the way to Salisbury Plain,” said Professor Kate Welham (Bournemouth University).

The research was funded by the British Academy, the Natural Environment Research Council (NERC), the National Geographic Society, the Society of Antiquaries, the Royal Archaeological Institute and the Cambrian Archaeological Association.

Coast-To-Coast Storm To Bring Weather Misery To 200 Million

A powerful storm that began its journey Sunday in California will roar across the country over the next two to three days, spreading heavy snow, torrential rain and crippling ice to more than 200 million Americans.

That’s about 60 percent of the population, AccuWeather said. “Parts of 39 of the 48 contiguous United States will be touched by the massive storm, including every state east of the Mississippi River,” AccuWeather meteorologist Faith Eherts said.

On Monday, the storm aimed its fury on the southern Rockies. As much as a foot of snow fell in Arizona, Colorado and New Mexico.

By Tuesday, the storm will spread heavy snow and strong winds into the central U.S., the National Weather Service said.

Late Tuesday and into Wednesday, the threat for heavy snow, ice and dangerous travel will expand across the Midwest, Ohio Valley, Mid Atlantic and the Northeast.

“Kansas City, Omaha, Des Moines, Minneapolis and Duluth could all receive several inches of snow,” said AccuWeather meteorologist Tyler Roys.

The Weather Channel warned that the Washington D.C., Baltimore and Philadelphia metro areas will see accumulating snow to start before it changes to a mix of sleet, freezing rain and then rain. That could make the Wednesday morning commute in those cities hazardous.

Freezing rain and ice will be especially dangerous in the mountains of West Virginia, Virginia and North Carolina, weather.com said, causing tree damage and scattered power outages. Lighter amounts of ice are forecast for portions of Indiana, Ohio and Pennsylvania.

In the South, several rounds of heavy, flooding rainfall and even some severe thunderstorms are expected Tuesday and Wednesday.

Up to a half foot of rain could swamp much of northern Mississippi, northern Alabama and Tennessee, where flood watches and warnings have been posted.

Summer will continue to pay an early visit to Florida on Tuesday as temperatures soar into the 80s. Several Florida cities set record highs Monday, including Vero Beach, which tied an all-time February record high of 89 degrees.

The unusual warmth is expected to continue in the Sunshine State for most of the week.

JUST IN: Fresco Painting of Narcissus Discovered in Pompeii

Archaeologists have discovered a fresco in an ancient Pompeii residence that portrays the mythological hunter Narcissus, who fell in love with his own reflection.

The discovery announced Thursday is in the atrium of a house where a fresco was found late last year depicting a sensual scene between the Roman god Jupiter disguised as a swan and Leda, a queen of Sparta from Greek mythology.

Pompeii director Alfonsina Russo said that the “beauty of these rooms” has prompted officials to continue to uncover more treasures so that one day the house can be at least partially opened to the public.

Officials noted archaeologists also found inside the ancient atrium a dozen glass containers, eight terracotta vases and a bronze funnel in a space underneath a staircase.

A Nearby River Of Stars

Astronomy & Astrophysics publishes the work of researchers from the University of Vienna, who have found a river of stars, a stellar stream in astronomical parlance, covering most of the southern sky. The stream is relatively nearby and contains at least 4000 stars that have been moving together in space since they formed, about 1 billion years ago. Due to its proximity to Earth, this stream is a perfect workbench on which to test the disruption of clusters, measure the gravitational field of the Milky Way, and learn about coeval extrasolar planet populations with upcoming planet-finding missions. For their search, the authors used data from the ESA Gaia satellite.

Our own host galaxy, the Milky Way, is home to star clusters of variable sizes and ages. We find many baby clusters within molecular clouds, fewer middle-age and old age clusters in the Galactic disk, and even fewer massive, old globular clusters in the halo. These clusters, regardless of their origin and age, are all subject to tidal forces along their orbits in the Galaxy. Given enough time, the Milky Way gravitational forces relentlessly pull them apart, dispersing their stars into the collection of stars we know as the Milky Way.

“Most star clusters in the Galactic disk disperse rapidly after their birth as they do not contain enough stars to create a deep gravitational potential well, or in other words, they do not have enough glue to keep them together. Even in the immediate solar neighborhood, there are, however, a few clusters with sufficient stellar mass to remain bound for several hundred million years. So, in principle, similar, large, stream-like remnants of clusters or associations should also be part of the Milky Way disk.” says Stefan Meingast, lead author of the paper published in Astronomy & Astrophysics.

Thanks to the precision of the Gaia measurements, the authors could measure the 3D motion of stars in space. When carefully looking at the distribution of nearby stars moving together, one particular group of stars, as yet unknown and unstudied, immediately caught the eye of the researchers. It was a group of stars that showed precisely the expected characteristics of a cluster of stars born together but being pulled apart by the gravitational field of the Milky Way.

“Identifying nearby disk streams is like looking for the proverbial needle in a haystack. Astronomers have been looking at, and through, this new stream for a long time, as it covers most of the night sky, but only now realize it is there, and it is huge, and shockingly close to the Sun” says João Alves, second author of the paper. “Finding things close to home is very useful, it means they are not too faint nor too blurred for further detailed exploration, as astronomers dream.”

Due to sensitivity limitations of the Gaia observations, their selection only contained about 200 sources. An extrapolation beyond these limits suggests the stream should have at least 4000 stars, thereby making the structure more massive than most know clusters in the immediate solar neighborhood. The authors also determined the stream’s age to be around one billion years. As such, it already has completed four full orbits around the Galaxy, enough time to develop the stream-like structure as a consequence of gravitational interaction with the Milky Way disk.

“As soon as we investigated this particular group of stars in more detail, we knew that we had found what we were looking for: A coeval, stream-like structure, stretching for hundreds of parsecs across a third of the entire sky.” Says Verena Fürnkranz, co-author and Masters student at the University of Vienna. “It was so thrilling to be part of a new discovery” she adds.

This newly discovered nearby system can be used as a valuable gravity probe to measure the mass of the Galaxy. With follow-up work, this stream can tell us how galaxies get their stars, test the gravitational field of the Milky Way, and, because of its proximity, become a wonderful target for planet-finding missions. The authors hope to unravel even more such structures in the future with the help of the rich Gaia database.