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.

Most Massive Neutron Star Ever Detected, Almost Too Massive To Exist

 

Neutron stars — the compressed remains of massive stars gone supernova — are the densest “normal” objects in the known universe. (Black holes are technically denser, but far from normal.) Just a single sugar-cube worth of neutron-star material would weigh 100 million tons here on Earth, or about the same as the entire human population. Though astronomers and physicists have studied and marveled at these objects for decades, many mysteries remain about the nature of their interiors: Do crushed neutrons become “superfluid” and flow freely? Do they breakdown into a soup of subatomic quarks or other exotic particles? What is the tipping point when gravity wins out over matter and forms a black hole?

A team of astronomers using the National Science Foundation’s (NSF) Green Bank Telescope (GBT) has brought us closer to finding the answers.

The researchers, members of the NANOGrav Physics Frontiers Center, discovered that a rapidly rotating millisecond pulsar, called J0740+6620, is the most massive neutron star ever measured, packing 2.17 times the mass of our Sun into a sphere only 30 kilometers across. This measurement approaches the limits of how massive and compact a single object can become without crushing itself down into a black hole. Recent work involving gravitational waves observed from colliding neutron stars by LIGO suggests that 2.17 solar masses might be very near that limit.

“Neutron stars are as mysterious as they are fascinating,” said Thankful Cromartie, a graduate student at the University of Virginia and Grote Reber pre-doctoral fellow at the National Radio Astronomy Observatory in Charlottesville, Virginia. “These city-sized objects are essentially ginormous atomic nuclei. They are so massive that their interiors take on weird properties. Finding the maximum mass that physics and nature will allow can teach us a great deal about this otherwise inaccessible realm in astrophysics.”

Pulsars get their name because of the twin beams of radio waves they emit from their magnetic poles. These beams sweep across space in a lighthouse-like fashion. Some rotate hundreds of times each second. Since pulsars spin with such phenomenal speed and regularity, astronomers can use them as the cosmic equivalent of atomic clocks. Such precise timekeeping helps astronomers study the nature of spacetime, measure the masses of stellar objects, and improve their understanding of general relativity.

In the case of this binary system, which is nearly edge-on in relation to Earth, this cosmic precision provided a pathway for astronomers to calculate the mass of the two stars.

As the ticking pulsar passes behind its white dwarf companion, there is a subtle (on the order of 10 millionths of a second) delay in the arrival time of the signals. This phenomenon is known as “Shapiro Delay.” In essence, gravity from the white dwarf star slightly warps the space surrounding it, in accordance with Einstein’s general theory of relativity. This warping means the pulses from the rotating neutron star have to travel just a little bit farther as they wend their way around the distortions of spacetime caused by the white dwarf.

Astronomers can use the amount of that delay to calculate the mass of the white dwarf. Once the mass of one of the co-orbiting bodies is known, it is a relatively straightforward process to accurately determine the mass of the other.

Cromartie is the principal author on a paper accepted for publication in Nature Astronomy. The GBT observations were research related to her doctoral thesis, which proposed observing this system at two special points in their mutual orbits to accurately calculate the mass of the neutron star.

“The orientation of this binary star system created a fantastic cosmic laboratory,” said Scott Ransom, an astronomer at NRAO and coauthor on the paper. “Neutron stars have this tipping point where their interior densities get so extreme that the force of gravity overwhelms even the ability of neutrons to resist further collapse. Each “most massive” neutron star we find brings us closer to identifying that tipping point and helping us to understand the physics of matter at these mindboggling densities.”

These observation were also part of a larger observing campaign known as NANOGrav, short for the North American Nanohertz Observatory for Gravitational Waves, which is a Physics Frontiers Center funded by the NSF.

Water Detected On An Exoplanet Located In Its Star’s Habitable Zone

 

 

Ever since the discovery of the first exoplanet in the 1990s, astronomers have made steady progress towards finding and probing planets located in the habitable zone of their stars, where conditions can lead to the formation of liquid water and the proliferation of life.

Results from the Kepler satellite mission, which discovered nearly 2/3 of all known exoplanets to date, indicate that 5 to 20% of Earths and super-Earths are located in the habitable zone of their stars. However, despite this abundance, probing the conditions and atmospheric properties on any of these habitable zone planets is extremely difficult and has remained elusive… until now.

A new study by Professor Björn Benneke of the Institute for Research on Exoplanets at the Université de Montréal, his doctoral student Caroline Piaulet and several of their collaborators reports the detection of water vapour and perhaps even liquid water clouds in the atmosphere of the planet K2-18b. This exoplanet is about nine times more massive than our Earth and is found in the habitable zone of the star it orbits. This M-type star is smaller and cooler than our Sun, but due to K2-18b’s close proximity to its star, the planet receives almost the same total amount of energy from its star as our Earth receives from the Sun.

The similarities between the exoplanet K2-18b and the Earth suggest to astronomers that the exoplanet may potentially have a water cycle possibly allowing water to condense into clouds and liquid water rain to fall. This detection was made possible by combining eight transit observations — the moment when an exoplanet passes in front of its star — taken by the Hubble Space Telescope.

The Université de Montréal is no stranger to the K2-18 system located 111 light years away. The existence of K2-18b was first confirmed by Prof. Benneke and his team in a 2016 paper using data from the Spitzer Space Telescope. The mass and radius of the planet were then determined by former Université de Montréal and University of Toronto PhD student Ryan Cloutier. These promising initial results encouraged the iREx team to collect follow-up observations of the intriguing world.”

Scientists currently believe that the thick gaseous envelope of K2-18b likely prevents life as we know it from existing on the planet’s surface. However, the study shows that even these planets of relatively low mass which are therefore more difficult to study can be explored using astronomical instruments developed in recent years. By studying these planets which are in the habitable zone of their star and have the right conditions for liquid water, astronomers are one step closer to directly detecting signs of life beyond our Solar System.

“This represents the biggest step yet taken towards our ultimate goal of finding life on other planets, of proving that we are not alone. Thanks to our observations and our climate model of this planet, we have shown that its water vapour can condense into liquid water. This is a first,” says Björn Benneke.

 

Scientists Detect The Ringing Of A Newborn Black Hole For The First Time

 

Now, physicists from MIT and elsewhere have “heard” the ringing of an infant black hole for the first time, and found that the pattern of this ringing does, in fact, predict the black hole’s mass and spin — more evidence that Einstein was right all along.

The findings, published today in Physical Review Letters, also favor the idea that black holes lack any sort of “hair” — a metaphor referring to the idea that black holes, according to Einstein’s theory, should exhibit just three observable properties: mass, spin, and electric charge. All other characteristics, which the physicist John Wheeler termed “hair,” should be swallowed up by the black hole itself, and would therefore be unobservable.

The team’s findings today support the idea that black holes are, in fact, hairless. The researchers were able to identify the pattern of a black hole’s ringing, and, using Einstein’s equations, calculated the mass and spin that the black hole should have, given its ringing pattern. These calculations matched measurements of the black hole’s mass and spin made previously by others.

If the team’s calculations deviated significantly from the measurements, it would have suggested that the black hole’s ringing encodes properties other than mass, spin, and electric charge — tantalizing evidence of physics beyond what Einstein’s theory can explain. But as it turns out, the black hole’s ringing pattern is a direct signature of its mass and spin, giving support to the notion that black holes are bald-faced giants, lacking any extraneous, hair-like properties.

“We all expect general relativity to be correct, but this is the first time we have confirmed it in this way,” says the study’s lead author, Maximiliano Isi, a NASA Einstein Fellow in MIT’s Kavli Institute for Astrophysics and Space Research. “This is the first experimental measurement that succeeds in directly testing the no-hair theorem. It doesn’t mean black holes couldn’t have hair. It means the picture of black holes with no hair lives for one more day.”

A chirp, decoded

On Sept. 9, 2015, scientists made the first-ever detection of gravitational waves — infinitesimal ripples in space-time, emanating from distant, violent cosmic phenomena. The detection, named GW150914, was made by LIGO, the Laser Interferometer Gravitational-wave Observatory. Once scientists cleared away the noise and zoomed in on the signal, they observed a waveform that quickly crescendoed before fading away. When they translated the signal into sound, they heard something resembling a “chirp.”

Scientists determined that the gravitational waves were set off by the rapid inspiraling of two massive black holes. The peak of the signal — the loudest part of the chirp — linked to the very moment when the black holes collided, merging into a single, new black hole. While this infant black hole likely gave off gravitational waves of its own, its signature ringing, physicists assumed, would be too faint to decipher amid the clamor of the initial collision.

Isi and his colleagues, however, found a way to extract the black hole’s reverberation from the moments immediately after the signal’s peak. In previous work led by Isi’s co-author, Matthew Giesler, the team showed through simulations that such a signal, and particularly the portion right after the peak, contains “overtones” — a family of loud, short-lived tones. When they reanalyzed the signal, taking overtones into account, the researchers discovered that they could successfully isolate a ringing pattern that was specific to a newly formed black hole.

In the team’s new paper, the researchers applied this technique to actual data from the GW150914 detection, concentrating on the last few milliseconds of the signal, immediately following the chirp’s peak. Taking into account the signal’s overtones, they were able to discern a ringing coming from the new, infant black hole. Specifically, they identified two distinct tones, each with a pitch and decay rate that they were able to measure.

“We detect an overall gravitational wave signal that’s made up of multiple frequencies, which fade away at different rates, like the different pitches that make up a sound,” Isi says. “Each frequency or tone corresponds to a vibrational frequency of the new black hole.”

Listening beyond Einstein

Einstein’s theory of general relativity predicts that the pitch and decay of a black hole’s gravitational waves should be a direct product of its mass and spin. That is, a black hole of a given mass and spin can only produce tones of a certain pitch and decay. As a test of Einstein’s theory, the team used the equations of general relativity to calculate the newly formed black hole’s mass and spin, given the pitch and decay of the two tones they detected.

They found their calculations matched with measurements of the black hole’s mass and spin previously made by others. Isi says the results demonstrate that researchers can, in fact, use the very loudest, most detectable parts of a gravitational wave signal to discern a new black hole’s ringing, where before, scientists assumed that this ringing could only be detected within the much fainter end of the gravitational wave signal, and only with much more sensitive instruments than what currently exist.

“This is exciting for the community because it shows these kinds of studies are possible now, not in 20 years,” Isi says.

As LIGO improves its resolution, and more sensitive instruments come online in the future, researchers will be able to use the group’s methods to “hear” the ringing of other newly born black holes. And if they happen to pick up tones that don’t quite match up with Einstein’s predictions, that could be an even more exciting prospect.

“In the future, we’ll have better detectors on Earth and in space, and will be able to see not just two, but tens of modes, and pin down their properties precisely,” Isi says. “If these are not black holes as Einstein predicts, if they are more exotic objects like wormholes or boson stars, they may not ring in the same way, and we’ll have a chance of seeing them.”

This research was supported, in part, by NASA, the Sherman Fairchild Foundation, the Simons Foundation, and the National Science Foundation.

Mantle Rock Behind Yellowstone’s Supereruptions Extends To Northern California

Victor Camp has spent a lifetime studying volcanic eruptions all over the world, starting in Saudi Arabia, then Iran, and eventually the Pacific Northwest. The geology lecturer finds mantle plumes that feed the largest of these eruptions fascinating, because of their massive size and the impact they can have on our environment.

Over the past two years, this abiding interest helped him connect the dots and discover that the mantle source rock that rises upward from beneath Yellowstone National Park to feed its periodic supereruptions also spreads out west all the way to Northern California and Oregon.

On its westward journey, it acts as the catalyst for fairly young—meaning less than 2 million years old—volcanic eruptions at places such as Craters of the Moon National Monument and Preserve in Idaho, before reaching Medicine Lake Volcano in the northeastern tip of California, close to the Oregon border.

The mantle rock spreads laterally through narrow flow-line channels well below the earth’s crust for over 500 miles, bifurcating twice: once as it leaves Yellowstone and again as it reaches the California-Oregon border. These lines end at Medicine Lake, an active volcano near Mount Shasta, and at Newberry Volcano, an active volcano about 20 miles south of Bend, Ore.

This discovery is significant because it reveals how mantle plumes similar to the one beneath Yellowstone behave as they feed the majority of the world’s largest volcanic eruptions of basaltic lava, including the ones in Hawaii.

“Since the plume is not controlled by plate tectonics, it can rise and emerge anywhere on earth, depending on where it manages to break through the earth’s surface,” Camp said. “So, knowing this will help us understand supereruptions that have occurred before, and those that will occur in the future.”

The results of his self-funded study were published in the journal Geology in May.

Mantle plumes are composed of very hot, low-density mantle rock. Mantle is one of three major layers of planet earth—we live on the earth’s crust, the thinnest layer, and mantle is the second denser layer that extends from about 100 kilometers (62 miles) below the earth’s surface all the way down to about 2,700 kilometers (about 1,680 miles), and further down is the core of the earth comprised mostly of iron mixed with a few other elements.

Mantle plumes are technically mantle rock, but because they are hotter and more buoyant than surrounding mantle they rise in a plume-like form. When the Yellowstone plume first reached the base level of the North American tectonic plate, it was blocked by the rigidity of the cold plate base which acted as a barrier. At this depth of about 100 kilometers, the plume began to decompress and melt, while simultaneously spreading laterally to the west.

The mantle rock that Camp traced to California took many millions of years to move out west. What’s interesting is that the source of the mantle rock under Yellowstone today originated at the core-mantle boundary geographically centered near present-day San Diego, but very deep beneath the earth’s surface we reside on—and took a circuitous route through different regions of the mantle before it rose up underneath the Yellowstone volcano.

Camp sourced seismic tomography images, similar to X-rays and CT-scans (computerized tomography scans), that show how the mantle plume ascended, and he analyzed field data as well as published chemistry and age data on volcanic rocks at the surface, to demonstrate its westward flow.

Earth’s Last Magnetic Field Reversal Took Far Longer Than Once Thought

Earth’s magnetic field seems steady and true—reliable enough to navigate by.

Yet, largely hidden from daily life, the field drifts, waxes and wanes. The magnetic North Pole is currently careening toward Siberia, which recently forced the Global Positioning System that underlies modern navigation to update its software sooner than expected to account for the shift.

And every several hundred thousand years or so, the magnetic field dramatically shifts and reverses its polarity: Magnetic north shifts to the geographic South Pole and, eventually, back again. This reversal has happened countless times over the Earth’s history, but scientists have only a limited understanding of why the field reverses and how it happens.

New work from University of Wisconsin-Madison geologist Brad Singer and his colleagues finds that the most recent field reversal, some 770,000 years ago, took at least 22,000 years to complete. That’s several times longer than previously thought, and the results further call into question controversial findings that some reversals could occur within a human lifetime.

The new analysis—based on advances in measurement capabilities and a global survey of lava flows, ocean sediments and Antarctic ice cores—provides a detailed look at a turbulent time for Earth’s magnetic field. Over millennia, the field weakened, partially shifted, stabilized again and then finally reversed for good to the orientation we know today.

The results provide a clearer and more nuanced picture of reversals at a time when some scientists believe we may be experiencing the early stages of a reversal as the field weakens and moves. Other researchers dispute the notion of a present-day reversal, which would likely affect our heavily electronic world in unusual ways.

Singer published his work Aug. 7 in the journal Science Advances. He collaborated with researchers at Kumamoto University in Japan and the University of California, Santa Cruz.

“Reversals are generated in the deepest parts of the Earth’s interior, but the effects manifest themselves all the way through the Earth and especially at the Earth’s surface and in the atmosphere,” explains Singer. “Unless you have a complete, accurate and high-resolution record of what a field reversal really is like at the surface of the Earth, it’s difficult to even discuss what the mechanics of generating a reversal are.”

Earth’s magnetic field is produced by the planet’s liquid iron outer core as it spins around the solid inner core. This dynamo action creates a field that is most stable going through roughly the geographic North and South poles, but the field shifts and weakens significantly during reversals.

As new rocks form—typically either as volcanic lava flows or sediments being deposited on the sea floor—they record the magnetic field at the time they were created. Geologists like Singer can survey this global record to piece together the history of magnetic fields going back millions of years. The record is clearest for the most recent reversal, named Matuyama-Brunhes after the researchers who first described reversals.

For the current analysis, Singer and his team focused on lava flows from Chile, Tahiti, Hawaii, the Caribbean and the Canary Islands. The team collected samples from these lava flows over several field seasons.

“Lava flows are ideal recorders of the magnetic field. They have a lot of iron-bearing minerals, and when they cool, they lock in the direction of the field,” says Singer. “But it’s a spotty record. No volcanoes are erupting continuously. So we’re relying on careful field work to identify the right records.”

The researchers combined magnetic readings and radioisotope dating of samples from seven lava flow sequences to recreate the magnetic field over a span of about 70,000 years centered on the Matuyama-Brunhes reversal. They relied on upgraded methods developed in Singer’s WiscAr geochronology lab to more accurately date the lava flows by measuring the argon produced from radioactive decay of potassium in the rocks.

They found that the final reversal was quick by geological standards, less than 4,000 years. But it was preceded by an extended period of instability that included two excursions—temporary, partial reversals—stretching back another 18,000 years. That span is more than twice as long as suggested by recent proposals that all reversals wrap up within 9,000 years.

The lava flow data was corroborated by magnetic readings from the seafloor, which provides a more continuous but less precise source of data than lava rocks. The researchers also used Antarctic ice cores to track the deposition of beryllium, which is produced by cosmic radiation colliding with the atmosphere. When the magnetic field is reversing, it weakens and allows more radiation to strike the atmosphere, producing more beryllium.

Since humanity began recording the strength of the magnetic field, it has decreased in strength about five percent each century. As records like Singer’s show, a weakening field seems to be a precursor to an eventual reversal, although it’s far from clear that a reversal is imminent.

A reversing field might significantly affect navigation and satellite and terrestrial communication. But the current study suggests that society would have generations to adapt to a lengthy period of magnetic instability.

“I’ve been working on this problem for 25 years,” says Singer, who stumbled into paleomagnetism when he realized the volcanoes he was studying served as a good record of Earth’s magnetic fields. “And now we have a richer record and better-dated record of this last reversal than ever before.”

Archaeologists Discover Almost 40 New Monuments Close To Newgrange

The research is part of the ‘Boyne to Brodgar’ project, which is examining connections between Neolithic sites in the Boyne Valley and the Orkney Islands.

The area surveyed included locations both sides of the Boyne, within the bend of the Boyne River, and across from the prehistoric tombs at Newgrange, Knowth and Dowth.

Newgrange is synonymous with the Winter Solstice, where the dawn light illuminates the burial chamber, and is among the best known of the passage tombs in Brú na Boinne.

Since 1993 the site has been a World Heritage Site designated by UNESCO.

Dr. Davis, who has worked for over a decade at Brú na Bóinne , said the monuments among the latest discoveries likely range from “early Neolithic houses to Neolithic timber enclosures as well as Bronze Age burial monuments and some early medieval farmsteads”.

“There are still significant gaps, most notably in our understanding of settlement, but we are continuing to work to understand these.”

The results of this year’s surveys “build on the exceptional summer last year in Brú na Bóinne and continue to demonstrate what a globally significant archaeological landscape we have in Brú na Bóinne,” he added.

When finished, the Boyne to Brodgar project, which began five years ago, will have surveyed more than five square kilometres.