Swarm Of Earthquakes Hits North Iceland

Almost thirty earthquakes occurred in North Iceland and the ocean north of Iceland last night. The largest earthquake of the swarm occcured at 2.30 AM at a magnitude of 3.0. Its origins were around 20 km North East of Siglufjörður.

The swarm began at around 00.30 last night and most of them were at a magnitude of between 1.0 and 2.0. An earthquake of 2.8 occurred North East of Grímsey.

The Iceland Met Office sees no cause for concern but is carefully monitoring events.

Kepler Solves Mystery Of Fast And Furious Explosions

The universe is full of mysterious exploding phenomena that go boom in the dark. One particular type of ephemeral event, called a Fast-Evolving Luminous Transient (FELT), has bewildered astronomers for a decade because of its very brief duration.

Now, NASA’s Kepler Space Telescope—designed to go hunting for planets across our galaxy—has also been used to catch FELTs in the act and determine their nature. They appear to be a new kind of supernova that gets a brief turbo boost in brightness from its surroundings.

Kepler’s ability to precisely sample sudden changes in starlight has allowed astronomers to quickly arrive at this model for explaining FELTs, and rule out alternative explanations.

Researchers conclude that the source of the flash is from a star after it collapses to explode as a supernova. The big difference is that the star is cocooned inside one or more shells of gas and dust. When the tsunami of explosive energy from the blast slams into the shell, most of the kinetic energy is immediately converted to light. The burst of radiation lasts for only a few days—one-tenth the duration of a typical supernova explosion.

Over the past decade several FELTs have been discovered with timescales and luminosities not easily explained by traditional supernova models. And, only a few FELTs have been seen in sky surveys because they are so brief. Unlike Kepler, which collects data on a patch of sky every 30 minutes, most other telescopes look every few days. Therefore they often slip through undetected or with only one or two measurements, making understanding the physics of these explosions tricky.

In the absence of more data, there have been a variety of theories to explain FELTs: the afterglow of a gamma-ray burst, a supernova boosted by a magnetar (neutron star with a powerful magnetic field), or a failed Type Ia supernova.

Then along came Kepler with its precise, continuous measurements that allowed astronomers to record more details of the FELT event. “We collected an awesome light curve,” said Armin Rest of the Space Telescope Science Institute in Baltimore, Maryland. “We were able to constrain the mechanism and the properties of the blast. We could exclude alternate theories and arrive at the dense-shell model explanation. This is a new way for massive stars to die and distribute material back into space.

“With Kepler, we are now really able to connect the models with the data,” he continued. “Kepler just makes all the difference here. When I first saw the Kepler data, and realized how short this transient is, my jaw dropped. I said, ‘Oh wow!'”

“The fact that Kepler completely captured the rapid evolution really constrains the exotic ways in which stars die. The wealth of data allowed us to disentangle the physical properties of the phantom blast, such as how much material the star expelled at the end of its life and the hypersonic speed of the explosion. This is the first time that we can test FELT models to a high degree of accuracy and really connect theory to observations,” said David Khatami of the University of California at Berkeley.

This discovery is an unexpected spinoff of Kepler’s unique capability to sample changes in starlight continuously for several months. This capability is needed for Kepler to discover extrasolar planets that briefly pass in front of their host stars, temporarily dimming starlight by a small percent.

The Kepler observations indicate that the star ejected the shell less than a year before it went supernova. This gives insight into the poorly understood death throes of stars—the FELTs apparently come from stars that undergo “near-death experiences” just before dying, belching out shells of matter in mini-eruptions before exploding entirely.

The science team’s study appears in the March 26, 2018 online issue of Nature Astronomy.

Rest says the next steps will be to find more of these objects in the ongoing K2 mission, or in the next mission of that kind, TESS. This will allow astronomers to start a follow-up campaign spanning different wavelength regimes, which constrains the nature and physics of this new kind of explosion.

Hubble Solves Cosmic ‘Whodunit’ With Interstellar Forensics

On the outskirts of our galaxy, a cosmic tug-of-war is unfolding-and only NASA’s Hubble Space Telescope can see who’s winning.

The players are two dwarf galaxies, the Large Magellanic Cloud and the Small Magellanic Cloud, both of which orbit our own Milky Way Galaxy. But as they go around the Milky Way, they are also orbiting each other. Each one tugs at the other, and one of them has pulled out a huge cloud of gas from its companion.

Called the Leading Arm, this arching collection of gas connects the Magellanic Clouds to the Milky Way. Roughly half the size of our galaxy, this structure is thought to be about 1 or 2 billion years old. Its name comes from the fact that it’s leading the motion of the Magellanic Clouds.

The enormous concentration of gas is being devoured by the Milky Way and feeding new star birth in our galaxy. But which dwarf galaxy is doing the pulling, and whose gas is now being feasted upon? After years of debate, scientists now have the answer to this “whodunit” mystery.

“There’s been a question: Did the gas come from the Large Magellanic Cloud or the Small Magellanic Cloud? At first glance, it looks like it tracks back to the Large Magellanic Cloud,” explained lead researcher Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland. “But we’ve approached that question differently, by asking: What is the Leading Arm made of? Does it have the composition of the Large Magellanic Cloud or the composition of the Small Magellanic Cloud?”

Fox’s research is a follow-up to his 2013 work, which focused on a trailing feature behind the Large and Small Magellanic Clouds. This gas in this ribbon-like structure, called the Magellanic Stream, was found to come from both dwarf galaxies. Now Fox wondered about its counterpart, the Leading Arm. Unlike the trailing Magellanic Stream, this tattered and shredded “arm” has already reached the Milky Way and survived its journey to the galactic disk.

The Leading Arm is a real-time example of gas accretion, the process of gas falling onto galaxies. This is very difficult to see in galaxies outside the Milky Way, because they are too far away and too faint. “As these two galaxies are in our backyard, we essentially have a front-row seat to view the action,” said collaborator Kat Barger at Texas Christian University.

In a new kind of forensics, Fox and his team used Hubble’s ultraviolet vision to chemically analyze the gas in the Leading Arm. They observed the light from seven quasars, the bright cores of active galaxies that reside billions of light-years beyond this gas cloud. Using Hubble’s Cosmic Origins Spectrograph, the scientists measured how this light filters through the cloud.

In particular, they looked for the absorption of ultraviolet light by oxygen and sulfur in the cloud. These are good gauges of how many heavier elements reside in the gas. The team then compared Hubble’s measurements to hydrogen measurements made by the National Science Foundation’s Robert C. Byrd Green Bank Telescope at the Green Bank Observatory in West Virginia, as well as several other radio telescopes.

“With the combination of Hubble and Green Bank Telescope observations, we can measure the composition and velocity of the gas to determine which dwarf galaxy is the culprit,” explained Barger.

After much analysis, the team finally had conclusive chemical “fingerprints” to match the origin of the Leading Arm’s gas. “We’ve found that the gas matches the Small Magellanic Cloud,” said Fox. “That indicates the Large Magellanic Cloud is winning the tug-of-war, because it has pulled so much gas out of its smaller neighbor.”

This answer was possible only because of Hubble’s unique ultraviolet capability. Because of the filtering effects of Earth’s atmosphere, ultraviolet light cannot be studied from the ground. “Hubble is the only game in town,” explained Fox. “All the lines of interest, including oxygen and sulfur, are in the ultraviolet. So if you work in the optical and infrared, you can’t see them.”

Gas from the Leading Arm is now crossing the disk of our galaxy. As it crosses, it interacts with the Milky Way’s own gas, becoming shredded and fragmented.

This is an important case study of how gas gets into galaxies and fuels star birth. Astronomers use simulations and try to understand the inflow of gas in other galaxies. But here, the gas is being caught red-handed as it moves across the Milky Way’s disk. Sometime in the future, planets and solar systems in our galaxy may be born out of material that used to be part of the Small Magellanic Cloud.

As Fox and his team look ahead, they hope to map out the full size of the Leading Arm-something that is still unknown.

Mysterious Head Of A Pharaoh Discovered By Swansea Egyptologist

Swansea University Egyptology lecturer Dr Ken Griffin has found a depiction of one of the most famous pharaoh’s in history Hatshepsut (one of only a handful of female pharaohs) on an object in the Egypt Centre stores, which had been chosen for an object handling session.

The opportunity to handle genuine Egyptian artefacts is provided by the Egypt Centre to students studying Egyptology at Swansea University. During a recent handling session for an Egyptian Art and Architecture module Dr Kenneth Griffin, from the University’s Department of Classics, Ancient History and Egyptology, noticed that one of the objects chosen was much more interesting than initially thought.

Consisting of two irregularly shaped limestone fragments that have been glued together, the object had been kept in storage for over twenty years and was requested for the handling session based only on an old black and white photograph.

The front side depicts the head of a figure whose face is unfortunately missing, with the remains of a fan directly behind. Traces of hieroglyphs are also present above the head. The iconography of the piece indicates that it represents a ruler of Egypt, particularly with the presence of the uraeus (cobra) on the forehead of the figure. Who is this mysterious pharaoh and where did the fragment originate from?

A search of the Egypt Centre records provides no information on the original provenance or find spot of the object. What is known is that it came to Swansea in 1971 as part of the distribution of objects belonging to Sir Henry Wellcome (1853-1936), the pharmaceutical entrepreneur based in London. The fragments are less than 5cm thick and had clearly been removed from the wall of a temple or tomb, as can be seen from the cut marks on the back.

Having visited Egypt on over fifty occasions, Dr Griffin quickly recognised the iconography as being similar to reliefs within the temple of Hatshepsut at Deir el-Bahri (Luxor), which was constructed during the height of the New Kingdom. In particular, the treatment of the hair, the fillet headband with twisted uraeus, and the decoration of the fan are all well-known at Deir el-Bahri.

Most importantly, the hieroglyphs above the head — part of a formulaic text attested elsewhere at the temple — use a feminine pronoun, a clear indication that the figure is female.

Hatshepsut was the fifth pharaoh of the Eighteenth Dynasty (c.1478-1458 BC) and one of only a handful of women to have held this position. Early in her reign she was represented as a female wearing a long dress, but she gradually took on more masculine traits, including being depicted with a beard. The reign of Hatshepsut was one of peace and prosperity, which allowed her to construct monuments throughout Egypt. Her memorial temple at Deir el-Bahri, built to celebrate and maintain her cult, is a masterpiece of Egyptian architecture.

Many fragments were taken from this site during the late nineteenth century, before the temple was excavated by the Egypt Exploration Fund (now Egypt Exploration Society) between 1902-1909. Since 1961 the Polish Archaeological Mission to Egypt has been excavating, restoring, and recording the temple.

Yet the mystery of the precious find doesn’t end there. On the rear of the upper fragment, the head of a man with a short beard is depicted. Initially there was no explanation for this, but it is now clear that the upper fragment had been removed and recarved in more recent times in order to complete the face of the lower fragment. The replacement of the fragment below the figure would also explain the unusual cut of the upper fragment. This was probably done by an antiques dealer, auctioneer, or even the previous owner of the piece in order to increase its value and attractiveness. It was eventually decided at an unknown date to glue the fragments together in the original layout, which is how they now appear.

While Deir el-Bahri seems the most likely provenance for this artefact, further research is needed in order to confirm this and it may even be possible to one day determine the exact spot the fragments originated from.

Given the importance of the object, the head of Hatshepsut has now been placed on display in a prominent position within the House of Life at the Egypt Centre so that the relief can be appreciated by visitors to the Centre.

Dr Griffin said: “The Egypt Centre is a wonderful resource and is certainly one of the major factors in attracting students to study Egyptology at Swansea University.”

“The identification of the object as depicting Hatshepsut caused great excitement amongst the students. After all, it was only through conducting handling sessions for them that this discovery came to light.”

“While most of the students have never visited Egypt before, the handling sessions help to bring Egypt to them.”

Landslide Modeling After Kaikoura Quake Provides Data To First Responders

Hours after the 2016 Kaikoura earthquake hit New Zealand, researchers were able to share information with first responders about where significant landsliding might have occurred to block roads and rivers, according to a new report in the Bulletin of the Seismological Society of America.

The modeling approach used to predict earthquake-related landslides was in the middle of being tested in New Zealand when the Kaikoura quake offered a serendipitous opportunity to test its capabilities, said Tom Robinson of Durham University in the United Kingdom.

Robinson and his colleagues were able to model landslide locations and runouts (the maximum distance landslide debris travels) within 24 hours of the event and produced a second, refined model 72 hours after the event. The modeling predicted that landsliding would be widespread and could impact major roads and numerous rivers. While the approach performed well at predicting road blockages, it overpredicted the occurrence of landslides in general, which limits the model’s use in determining the exact location of all landslides.

However, this near-real time analysis allowed members of the New Zealand Civil Defence and other responders to plan reconnaissance flights over the affected regions to determine where the landslides might cause further damage.

“For me, that’s the really exciting thing about this research, that we’re actually able to translate hazard knowledge into ‘here is where the impacts could be’ and ‘here are where losses could be as a result of that,'” said Robinson.

“Landslides used to get forgotten a lot in earthquakes, but that is changing now,” he said, after recent studies have confirmed that significant damage to infrastructure such as roads often results from subsequent landsliding, and not the ground shaking that occurs during an earthquake.

In mountainous regions such as in Nepal or China, up to 25% or more of earthquake fatalities can come from landsliding, Robinson noted.

A landslide inventory completed after the magnitude 7.8 Kaikoura event counted more than 10,000 landslides, blocking roads, rivers and railways, and damaging agricultural areas, according to another BSSA study led by Chris Massey of GNS Science in New Zealand.

Robinson said the Kaikoura earthquake did comparatively little damage to buildings in New Zealand, a country with strong earthquake building codes, “yet the landslides on the roads, particularly State Highway 1, which was the main road that was affected, have been catastrophic.”

When he visited the region in November 2017, a year after the earthquake, only one lane of State Highway 1 had been opened and the road remained closed overnight and during strong rain, including a cyclone that washed new debris into the roadway. The estimate for restoring the highway to full capacity is close to NZ$1 billion, Robinson said.

Landslides are “extremely complicated to predict” and are most often studied after the fact, he noted. To remedy this, he and his colleagues have developed modeling approaches that draw from recent global data collected on landslide hazards, “to see if we can learn something from multiple events and use that to predict where landslides might happen in future events elsewhere.”

The researchers combined these data in their model with information on landslide reach angles, a measurement that helps determine the maximum runout. Their model is one of the first to attempt to predict where landslides might block roads and dam up rivers after an earthquake in near real-time.

Information on both of these impacts, but especially landslide dams, is important for first responders, “Landslide dams often happen in remote, difficult terrain, and are often spotted only by chance,” said Robinson. “These dams can overtop and cause outburst flooding very quickly, and can be very dangerous to downstream communities.”

The New Zealand model was designed to predict the likelihood of landslides occurring in 25 x 25 meter cells across the affected area. To verify the model, an inventory of landslide points collected after the earthquake was used. The model’s overprediction tendency might be an artifact of how these landslides are represented by points, Robinson said, since a large landslide might in reality encompass hundreds or thousands of cells.

Fixing the overprediction problem might also require knowing more about the factors that drive landsliding, he said. “There are also so many different factors that contribute to landsliding, and even if we know relatively well what those factors are, it still seems to be somewhat random whether a slope will fail or not.

“For instance, we know shaking and slope angle drive the majority of landsliding, but in that part of New Zealand, you have high slope angles everywhere, and everywhere got shaken strongly, but not every slope fell down, so there are other intricacies at work there,” he added.

Modeling after the Kaikoura earthquake had to be done manually, but automating the program could significantly reduce the time needed to make landslide predictions after an earthquake, Robinson said.

He and his colleagues say more high resolution global data on landslides, including 3D satellite imaging, could help refine the landsliding model and allow it to be used around the world. But storing and manipulating these data would require more computer capacity, Robinson noted. “At the moment this is just done on a simple desktop like somebody might have at home.”

“In the immediate hours after an earthquake, it’s not possible for us to get satellite imagery to map every single landslide,” he said. “This is where we think modeling could potentially fill a gap, in the days after an earthquake when responders need information.”

Astronomers Discover A Giant Planet Orbiting A Brown Dwarf

Using microlensing technique, astronomers have found a new giant planet orbiting a brown dwarf located in the bulge of the Milky Way galaxy. The newly discovered exoplanet, designated OGLE-2017-BLG-1522Lb, is most likely 25 percent less massive than Jupiter. The finding is reported March 14 in a paper published on arXiv.org.

Based on the gravitational lens effect, the microlensing method is mainly used to detect planetary and stellar-mass objects regardless of the light they emit. This technique is therefore sensitive to the mass of the objects, especially to low-mass planets orbiting beyond the so-called “snow line” around relatively faint host stars like M dwarfs or brown dwarfs. Such planets are of special interest for astronomers, as just beyond this line, the most active planet formation occurs.

The OGLE-2017-BLG-1522 microlensing event was detected August 7, 2017 by the Optical Gravitational Lensing Experiment (OGLE) using the 1.3m Warsaw telescope at the Las Campanas Observatory in Chile. Afterward, an international team of astronomers, including scientists from the OGLE Collaboration and the Korea Microlensing Telescope Network (KMTNet) Collaboration, has analyzed the event and found a system composed of a brown dwarf orbited by a giant planet.

“We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively short event timescale of tE ~ 7.5 days,” the researchers wrote in the paper.

According to the study, OGLE-2017-BLG-1522Lb is a giant planet with a mass of about 0.75 Jupiter masses, orbiting its host at a distance of about 0.59 AU. The researchers noted that they are 75 percent sure that the host is a brown dwarf approximately 46 times more massive than our solar system’s biggest planet. Therefore, additional observations should be conducted in order to definitely confirm whether the host is a low-mass star or a an intermediate-mass brown dwarf.

The projected companion-host separation indicates that OGLE-2017-BLG-1522Lb is placed beyond the snow line—the distance at which molecular species freeze, thus where the planet formation starts. Moreover, the authors of the paper calculated that the system is located in the galactic bulge.

In concluding remarks, the astronomers underlined the importance of their discovery, noting that OGLE-2017-BLG-1522Lb could be the first giant planet orbiting around a brown dwarf host having a planetary mass ratio.

“Planet formation scenarios combined with the small companion-host mass ratio q ∼ 0.016 and separation suggest that the companion could be the first discovery of a giant planet that formed in a protoplanetary disk around a brown dwarf host,” the scientists concluded.

6.3-Magnitude Earthquake Hits Papua New Guinea

A 6.3-magnitude earthquake struck off the north-east coast of an island of the Pacific Ocean nation of Papua New Guinea on Saturday (March 24), officials said, but the tremor posed no tsunami threat to the region.

There were no immediate reports of damage or casualties from the quake, which was centred in a much more remote region than a magnitude-7.5 tremor that rocked the country’s mountainous mainland highlands on Feb 26, killing 100 people.

The epicentre of Saturday’s quake was located 180km south-west of Rabaul on New Britain island, some 900km north-east of the capital Port Moresby, at a depth of 68km, the US Geological Survey (USGS) said.

The quake was revised down from an initial reading of magnitude 6.8 and a depth of 60km.

“Based on all available data a destructive Pacific-wide tsunami is not expected,” the Hawaii-based Pacific Tsunami Warning Centre said in a bulletin.

Quakes are common in Papua New Guinea, which sits on the Pacific’s “Ring of Fire”, a hotspot for seismic activity due to friction between tectonic plates. Rabaul lies in the shadow of Mount Tavurvur, an active volcano that destroyed the town in 1994 during a severe eruption.

The latest quake comes as Papua New Guinea struggles to get aid to desperate survivors of the Feb 26 quake, which flattened whole villages and spoiled water supplies on the country’s main island.

A month on, disaster and relief officials say the scale of the emergency is testing the finances and capacity of one of the world’s poorest countries.

The impoverished country is also missing its largest revenue-earner, after the quake forced a shutdown of Exxon Mobil Corp’s liquefied natural gas (LNG) project, which has annual sales of US$3 billion (S$3.95 billion) at current LNG prices.

The firm is still assessing quake damage at its facilities.