Month: January 2019

Panicked Residents Flee Their Home As 6.6-Magnitude Earthquake Rocks Aru Islands

A 6.6-magnitude earthquake rocked the Aru Islands, Maluku, on Saturday at 5:12 p.m. local time, prompting residents to run out of their homes.

Two buildings were damaged. No injuries or casualties have been reported.

The earthquake’s epicenter was detected northwest off the coast of Dobo, the center of the archipelagic regency, and at a depth of 10 kilometers. Tremors were felt as far away as Timika, Papua.

They were strong enough to lightly damage a house and a hospital in Dobo, according to the National Disaster Mitigation Agency (BNPB).

“All of us ran outside because the tremors were strong,” said Dobo resident Demy as quoted by kompas.com.

He also said that the earthquake lasted almost 10 seconds.

Local authorities are still assessing the extent of the damage caused by the earthquake.

Earthquake: 6.2 Quake Strikes Near Taro, Solomon Islands

A deep magnitude 6.2 earthquake was reported Friday evening 22 miles from Taro, Solomon Islands, according to the U.S. Geological Survey. The temblor occurred at 7:51 p.m. Pacific time at a depth of 221.8 miles.

According to the USGS, the epicenter was 73 miles from Arawa, Papua New Guinea.

In the last 10 days, there have been no earthquakes of magnitude 3.0 or greater centered nearby.

How To Escape A Black Hole: Simulations Provide New Clues About Powerful Plasma Jets

Black holes are known for their voracious appetites, binging on matter with such ferocity that not even light can escape once it’s swallowed up.

Less understood, though, is how black holes purge energy locked up in their rotation, jetting near-light-speed plasmas into space to opposite sides in one of the most powerful displays in the universe. These jets can extend outward for millions of light years.

New simulations led by researchers working at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have combined decades-old theories to provide new insight about the driving mechanisms in the plasma jets that allows them to steal energy from black holes’ powerful gravitational fields and propel it far from their gaping mouths.

The simulations could provide a useful comparison for high-resolution observations from the Event Horizon Telescope, an array that is designed to provide the first direct images of the regions where the plasma jets form.

The telescope will enable new views of the black hole at the center of our own Milky Way galaxy, as well as detailed views of other supermassive black holes.

“How can the energy in a black hole’s rotation be extracted to make jets?” said Kyle Parfrey, who led the work on the simulations while he was an Einstein Postdoctoral Fellow affiliated with the Nuclear Science Division at Berkeley Lab. “This has been a question for a long time.”

Now a senior fellow at NASA Goddard Space Flight Center in Maryland, Parfrey is the lead author of a study, published Jan. 23 in Physical Review Letters, that details the simulations research.

The simulations, for the first time, unite a theory that explains how electric currents around a black hole twist magnetic fields into forming jets, with a separate theory explaining how particles crossing through a black hole’s point of no return — the event horizon — can appear to a distant observer to carry in negative energy and lower the black hole’s overall rotational energy.

It’s like eating a snack that causes you to lose calories rather than gaining them. The black hole actually loses mass as a result of slurping in these “negative-energy” particles.

Computer simulations have difficulty in modeling all of the complex physics involved in plasma-jet launching, which must account for the creation of pairs of electrons and positrons, the acceleration mechanism for particles, and the emission of light in the jets.

Berkeley Lab has contributed extensively to plasma simulations over its long history. Plasma is a gas-like mixture of charged particles that is the universe’s most common state of matter.

Parfrey said he realized that more complex simulations to better describe the jets would require a combination of expertise in plasma physics and the general theory of relativity.

“I thought it would be a good time to try to bring these two things together,” he said.

Performed at a supercomputing center at NASA Ames Research Center in Mountain View, California, the simulations incorporate new numerical techniques that provide the first model of a collisionless plasma — in which collisions between charged particles do not play a major role — in the presence of a strong gravitational field associated with a black hole.

The simulations naturally produce effects known as the Blandford-Znajek mechanism, which describes the twisting magnetic fields that form jets, and a separate Penrose process that describes what happens when negative-energy particles are gulped down by the black hole.

The Penrose process, “even though it doesn’t necessarily contribute that much to extracting the black hole’s rotation energy,” Parfrey said, “is possibly directly linked to the electric currents that twist the jets’ magnetic fields.”

While more detailed than some earlier models, Parfrey noted that his team’s simulations are still playing catch-up with observations, and are idealized in some ways to simplify the calculations needed to perform the simulations.

The team intends to better model the process by which electron-positron pairs are created in the jets in order to study the jets’ plasma distribution and their emission of radiation more realistically for comparison to observations. They also plan to broaden the scope of the simulations to include the flow of infalling matter around the black hole’s event horizon, known as its accretion flow.

“We hope to provide a more consistent picture of the whole problem,” he said.

Planetary Collision That Formed The Moon Made Life Possible On Earth

Most of Earth’s essential elements for life — including most of the carbon and nitrogen in you — probably came from another planet.

Earth most likely received the bulk of its carbon, nitrogen and other life-essential volatile elements from the planetary collision that created the moon more than 4.4 billion years ago, according to a new study by Rice University petrologists in the journal Science Advances.

“From the study of primitive meteorites, scientists have long known that Earth and other rocky planets in the inner solar system are volatile-depleted,” said study co-author Rajdeep Dasgupta. “But the timing and mechanism of volatile delivery has been hotly debated. Ours is the first scenario that can explain the timing and delivery in a way that is consistent with all of the geochemical evidence.”

The evidence was compiled from a combination of high-temperature, high-pressure experiments in Dasgupta’s lab, which specializes in studying geochemical reactions that take place deep within a planet under intense heat and pressure.

In a series of experiments, study lead author and graduate student Damanveer Grewal gathered evidence to test a long-standing theory that Earth’s volatiles arrived from a collision with an embryonic planet that had a sulfur-rich core.

The sulfur content of the donor planet’s core matters because of the puzzling array of experimental evidence about the carbon, nitrogen and sulfur that exist in all parts of the Earth other than the core.

“The core doesn’t interact with the rest of Earth, but everything above it, the mantle, the crust, the hydrosphere and the atmosphere, are all connected,” Grewal said. “Material cycles between them.”

One long-standing idea about how Earth received its volatiles was the “late veneer” theory that volatile-rich meteorites, leftover chunks of primordial matter from the outer solar system, arrived after Earth’s core formed. And while the isotopic signatures of Earth’s volatiles match these primordial objects, known as carbonaceous chondrites, the elemental ratio of carbon to nitrogen is off. Earth’s non-core material, which geologists call the bulk silicate Earth, has about 40 parts carbon to each part nitrogen, approximately twice the 20-1 ratio seen in carbonaceous chondrites.

Grewal’s experiments, which simulated the high pressures and temperatures during core formation, tested the idea that a sulfur-rich planetary core might exclude carbon or nitrogen, or both, leaving much larger fractions of those elements in the bulk silicate as compared to Earth. In a series of tests at a range of temperatures and pressure, Grewal examined how much carbon and nitrogen made it into the core in three scenarios: no sulfur, 10 percent sulfur and 25 percent sulfur.

“Nitrogen was largely unaffected,” he said. “It remained soluble in the alloys relative to silicates, and only began to be excluded from the core under the highest sulfur concentration.”

Carbon, by contrast, was considerably less soluble in alloys with intermediate sulfur concentrations, and sulfur-rich alloys took up about 10 times less carbon by weight than sulfur-free alloys.

Using this information, along with the known ratios and concentrations of elements both on Earth and in non-terrestrial bodies, Dasgupta, Grewal and Rice postdoctoral researcher Chenguang Sun designed a computer simulation to find the most likely scenario that produced Earth’s volatiles. Finding the answer involved varying the starting conditions, running approximately 1 billion scenarios and comparing them against the known conditions in the solar system today.

“What we found is that all the evidence — isotopic signatures, the carbon-nitrogen ratio and the overall amounts of carbon, nitrogen and sulfur in the bulk silicate Earth — are consistent with a moon-forming impact involving a volatile-bearing, Mars-sized planet with a sulfur-rich core,” Grewal said.

Dasgupta, the principal investigator on a NASA-funded effort called CLEVER Planets that is exploring how life-essential elements might come together on distant rocky planets, said better understanding the origin of Earth’s life-essential elements has implications beyond our solar system.

“This study suggests that a rocky, Earth-like planet gets more chances to acquire life-essential elements if it forms and grows from giant impacts with planets that have sampled different building blocks, perhaps from different parts of a protoplanetary disk,” Dasgupta said.

“This removes some boundary conditions,” he said. “It shows that life-essential volatiles can arrive at the surface layers of a planet, even if they were produced on planetary bodies that underwent core formation under very different conditions.”

Dasgupta said it does not appear that Earth’s bulk silicate, on its own, could have attained the life-essential volatile budgets that produced our biosphere, atmosphere and hydrosphere.

“That means we can broaden our search for pathways that lead to volatile elements coming together on a planet to support life as we know it.”

Birth Of Massive Black Holes In The Early Universe

The light released from around the first massive black holes in the universe is so intense that it is able to reach telescopes across the entire expanse of the universe. Incredibly, the light from the most distant black holes (or quasars) has been traveling to us for more than 13 billion light years. However, we do not know how these monster black holes formed.

New research led by researchers from Georgia Institute of Technology, Dublin City University, Michigan State University, the University of California at San Diego, the San Diego Supercomputer Center and IBM, provides a new and extremely promising avenue for solving this cosmic riddle. The team showed that when galaxies assemble extremely rapidly — and sometimes violently — that can lead to the formation of very massive black holes. In these rare galaxies, normal star formation is disrupted and black hole formation takes over.

The new study finds that massive black holes form in dense starless regions that are growing rapidly, turning upside down the long-accepted belief that massive black hole formation was limited to regions bombarded by the powerful radiation of nearby galaxies. Conclusions of the study, reported on January 23rd in the journal Nature and supported by funding from the National Science Foundation, the European Union and NASA, also finds that massive black holes are much more common in the universe than previously thought.

The key criteria for determining where massive black holes formed during the universe’s infancy relates to the rapid growth of pre-galactic gas clouds that are the forerunners of all present-day galaxies, meaning that most supermassive black holes have a common origin forming in this newly discovered scenario, said John Wise, an associate professor in the Center for Relativistic Astrophysics at Georgia Tech and the paper’s corresponding author. Dark matter collapses into halos that are the gravitational glue for all galaxies. Early rapid growth of these halos prevented the formation of stars that would have competed with black holes for gaseous matter flowing into the area.

“In this study, we have uncovered a totally new mechanism that sparks the formation of massive black holes in particular dark matter halos,” Wise said. “Instead of just considering radiation, we need to look at how quickly the halos grow. We don’t need that much physics to understand it — just how the dark matter is distributed and how gravity will affect that. Forming a massive black hole requires being in a rare region with an intense convergence of matter.”

When the research team found these black hole formation sites in the simulation, they were at first stumped, said John Regan, research fellow in the Centre for Astrophysics and Relativity in Dublin City University. The previously accepted paradigm was that massive black holes could only form when exposed to high levels of nearby radiation.

“Previous theories suggested this should only happen when the sites were exposed to high levels of star-formation killing radiation,” he said. “As we delved deeper, we saw that these sites were undergoing a period of extremely rapid growth. That was the key. The violent and turbulent nature of the rapid assembly, the violent crashing together of the galaxy’s foundations during the galaxy’s birth prevented normal star formation and led to perfect conditions for black hole formation instead. This research shifts the previous paradigm and opens up a whole new area of research.”

The earlier theory relied on intense ultraviolet radiation from a nearby galaxy to inhibit the formation of stars in the black hole-forming halo, said Michael Norman, director of the San Diego Supercomputer Center at UC San Diego and one of the work’s authors. “While UV radiation is still a factor, our work has shown that it is not the dominant factor, at least in our simulations,” he explained.

The research was based on the Renaissance Simulation suite, a 70-terabyte data set created on the Blue Waters supercomputer between 2011 and 2014 to help scientists understand how the universe evolved during its early years. To learn more about specific regions where massive black holes were likely to develop, the researchers examined the simulation data and found ten specific dark matter halos that should have formed stars given their masses but only contained a dense gas cloud. Using the Stampede2 supercomputer, they then re-simulated two of those halos — each about 2,400 light-years across — at much higher resolution to understand details of what was happening in them 270 million years after the Big Bang.

“It was only in these overly-dense regions of the universe that we saw these black holes forming,” Wise said. “The dark matter creates most of the gravity, and then the gas falls into that gravitational potential, where it can form stars or a massive black hole.”

The Renaissance Simulations are the most comprehensive simulations of the earliest stages of the gravitational assembly of the pristine gas composed of hydrogen and helium and cold dark matter leading to the formation of the first stars and galaxies. They use a technique known as adaptive mesh refinement to zoom in on dense clumps forming stars or black holes. In addition, they cover a large enough region of the early universe to form thousands of objects — a requirement if one is interested in rare objects, as is the case here. “The high resolution, rich physics and large sample of collapsing halos were all needed to achieve this result,” said Norman.

The improved resolution of the simulation done for two candidate regions allowed the scientists to see turbulence and the inflow of gas and clumps of matter forming as the black hole precursors began to condense and spin. Their growth rate was dramatic.

“Astronomers observe supermassive black holes that have grown to a billion solar masses in 800 million years,” Wise said. “Doing that required an intense convergence of mass in that region. You would expect that in regions where galaxies were forming at very early times.”

Another aspect of the research is that the halos that give birth to black holes may be more common than previously believed.

“An exciting component of this work is the discovery that these types of halos, though rare, may be common enough,” said Brian O’Shea, a professor at Michigan State University. “We predict that this scenario would happen enough to be the origin of the most massive black holes that are observed, both early in the universe and in galaxies at the present day.”

Future work with these simulations will look at the lifecycle of these massive black hole formation galaxies, studying the formation, growth and evolution of the first massive black holes across time. “Our next goal is to probe the further evolution of these exotic objects. Where are these black holes today? Can we detect evidence of them in the local universe or with gravitational waves?” Regan asked.

For these new answers, the research team — and others — may return to the simulations.

“The Renaissance Simulations are sufficiently rich that other discoveries can be made using data already computed,” said Norman. “For this reason we have created a public archive at SDSC containing called the Renaissance Simulations Laboratory where others can pursue questions of their own.”

Where Is Earth’s Submoon?

“Can moons have moons?”

This simple question — asked by the four-year old son of Carnegie’s Juna Kollmeier — started it all. Not long after this initial bedtime query, Kollmeier was coordinating a program at the Kavli Institute for Theoretical Physics (KITP) on the Milky Way while her one-time college classmate Sean Raymond of Université de Bordeaux was attending a parallel KITP program on the dynamics of Earth-like planets. After discussing this very simple question at a seminar, the two joined forces to solve it. Their findings are the basis of a paper published in Monthly Notices of the Royal Astronomical Society.

The duo kicked off an internet firestorm late last year when they posted a draft of their article examining the possibility of moons that orbit other moons on a preprint server for physics and astronomy manuscripts.

The online conversation obsessed over the best term to describe such phenomena with options like moonmoons and mini-moons being thrown into the mix. But nomenclature was not the point of Kollmeier and Raymond’s investigation (although they do have a preference for submoons). Rather, they set out to define the physical parameters for moons that would be capable of being stably orbited by other, smaller moons.

“Planets orbit stars and moons orbit planets, so it was natural to ask if smaller moons could orbit larger ones,” Raymond explained.

Their calculations show that only large moons on wide orbits from their host planets could host submoons. Tidal forces from both the planet and moon act to destabilize the orbits of submoons orbiting smaller moons or moons that are closer to their host planet.

They found that four moons in our own Solar System are theoretically capable of hosting their own satellite submoons. Jupiter’s moon Callisto, Saturn’s moons Titan and Iapetus, and Earth’s own Moon all fit the bill of a satellite that could host its own satellite, although none have been found so far. However, they add that further calculations are needed to address possible sources of submoon instability, such as the non-uniform concentration of mass in our Moon’s crust.

“The lack of known submoons in our Solar System, even orbiting around moons that could theoretically support such objects, can offer us clues about how our own and neighboring planets formed, about which there are still many outstanding questions,” Kollmeier explained.

The moons orbiting Saturn and Jupiter are thought to have been born from the disk of gas and dust that encircle gas giant planets in the later stages of their formation. Our own Moon, on the other hand, is thought to have originated in the aftermath of a giant impact between the young Earth and a Mars-sized body. The lack of stable submoons could help scientists better understand the different forces that shaped the satellites we do see.

Kollmeier added: “and, of course, this could inform ongoing efforts to understand how planetary systems evolve elsewhere and how our own Solar System fits into the thousands of others discovered by planet-hunting missions.”

For example, the newly discovered possible exomoon orbiting the Jupiter-sized Kepler 1625b is the right mass and distance from its host to support a submoon, Kollmeier and Raymond found. Although, the inferred tilt of its orbit might make it difficult for such an object to remain stable. However, detecting a submoon around an exomoon would be very difficult.

Given the excitement surrounding searches for potentially habitable exoplanets, Kollmeier and Raymond calculated that the best case scenario for life on large submoons is around massive stars. Although extremely common, small red dwarf stars are so faint and their habitable zones so close that tidal forces are very strong and submoons (and often even moons themselves) are unstable.

Finally, the authors point out that an artificial submoon may be stable and thereby serve as a time capsule or outpost. On a stable orbit around the Moon — such as the one for NASA’s proposed Lunar Gateway — a submoon would keep humanity’s treasures safe for posterity long after Earth became unsuitable for life. Kollmeier and Raymond agree that there is much more work to be done (and fun to be had) to understand submoons (or the lack thereof) as a rocky record of the history of planet-moon systems.

Sean Raymond maintains a science blog (planetplanet.net) where more details and illustrations (including a poem he wrote about the article) can be found.

This research was supported by a grant from the Agence Nationale pour la Recherche, the NASA Astrobiology Institute’s Virtual Planetary Laboratory Lead Team, and the National Science Foundation.

UPDATE : Large Storm Hitting Central US, Heading East With Flooding Rain, Strong Winds

A large storm that developed in the central U.S. is moving east on Wednesday and bringing snow, a wintry mix, severe weather and flooding rain.

he storm dumped over 17 inches of snow in the mountains of Colorado, and widespread 2 to 4 inches of snow from the Colorado Plains to the upper Midwest. Freezing rain also was reported in parts of Iowa, Illinois and Indiana on Tuesday night.

Locally heavy snow is moving through parts of the Midwest, including Cedar Rapids, Iowa, and Milwaukee, Wisconsin, on Wednesday morning. In Chicago, a wintry mix, with some snow, is possible as colder air is being wrapped into the storm. However, most of the frozen precipitation will stay north and west of the city. A dangerous morning commute is likely in these areas.

Additionally, a wintry mix is likely across parts New York state Wednesday morning as precipitation is interacting with colder air.

There are numerous alerts being issued for this wide-ranging storm, including winter storm warnings and winter weather advisories from Kansas to Michigan to Maine. Since there is a threat for heavy rain in the Northeast, there are new flood watches being issued for the major cities, including New York, Philadelphia and Washington, D.C. Additionally, there are alerts being issued for blowing snow in the Northern Plains in the storm’s wake.

A line of very heavy rain will extend through the Mississippi and Tennessee Valley late in the day Wednesday. Additionally, severe weather is likely across parts of the Gulf — from New Orleans to Mobile — where damaging winds and brief tornadoes are possible. Since this cold front is very strong, it will also cause gusty winds over 35 mph in spots.

Out ahead of the cold front, very mild air will surge up the East Coast. Temperatures will be 10 to 20 degrees above average in the New York City area, where temperatures might be in the mid-50s Thursday morning. But the warmth will be brief.

Early Thursday morning, the heavy rain and strong winds will move into the southeast U.S. and toward Atlanta. By Thursday morning, the line of heavy rain, with some locally strong thunderstorms, will stretch along the entire East Coast. Very heavy rain will fall Thursday during morning rush hour in the major northeast cities. Locally, 1 to 2 inches of rain could cause flash flooding and strong gusty winds are possible.

An additional complication in parts of the Northeast is that the heavy rain, combined with mild temperatures, will cause last week’s snow to rapidly melt and cause additional flooding concerns.

Chill behind the storm

Behind this storm, another frontal system will pass and deliver a cold blast. Wind chills on Friday in the Midwest will dip locally to minus 30 degrees. Chicago will feel like minus 21 on Friday morning.

Some of this cold air makes its way east, but moderates before reaching the major Northeast cities. It will not be as cold as last weekend.

However, another powerful blast of cold air will come in behind it over the weekend and wind chills approaching minus 50 are possible in parts of the upper Midwest by Sunday. Duluth will feel like minus 47 and Minneapolis like minus 29 on Sunday morning — this is life-threatening cold.