Month: October 2018

JUST IN: Newly Detected Gamma-Rays From Milky Way

The first-ever detection of highly energetic radiation from a microquasar has astrophysicists scrambling for new theories to explain the extreme particle acceleration. The team’s observations led by Hui Li, Los Alamos National Laboratory’s Theoretical Division says; “”What’s amazing about this discovery is that all current particle acceleration theories have difficulties explaining the observations.”

A microquasar is a black hole that gobbles up debris from a nearby companion star and blasts out powerful jets of material. The team’s observations, described in the Oct. 4 issue of the journal Nature, strongly suggest that particle collisions at the ends of the microquasar’s jets produced the powerful gamma rays. Scientists think that studying messages from this microquasar, dubbed SS 433, may offer a glimpse into more extreme events happening at the centers of distant galaxies.

The team gathered data from the High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC), which is a mountain-top detector in Mexico that observes gamma ray emission from supernova remnants, rotating dense stars called pulsars, and quasars. Los Alamos, funded by Department of Energy Office of High-Energy Physics, helped build HAWC, which was completed in 2015.

Based on their analysis, the researchers concluded that electrons in the jets attain energies that are about 1,000 times higher than can be achieved using earth-bound particle accelerators, such as the Large Hadron Collider. The jet electrons collide with the low-energy microwave background radiation that permeates space, resulting in gamma ray emission. This is a newly observed mechanism for getting high-energy gamma rays out of this kind of system and is different from what scientists have observed when the jets are aimed at Earth.

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Alexa’s and Sophia’s Kids Heart Challenge Fundraiser (American Heart Association)

At my school, I’m learning how I can help make a difference by raising lifesaving donations to help kids with heart disease.  I’m also learning about my own heart, and how to keep it healthy. And I’m getting active!

I’m excited about raising money for other kids – kids with hearts that don’t exactly work right and to help fund new medicines and treatments to be discovered.                     Please help me make a difference!  Thank you!

Alexa’s Link: http://bit.ly/2y1xSV5

Sophia’s Link: http://bit.ly/2PgnhfK

 

UPDATE : Typhoon Kong-Rey Heads Toward Japan

Typhoon Kong-rey is expected to make landfall in Japan on Saturday, becoming the ninth tropical storm to hit the country this year.

When it lands, Kong-rey is expected to have wind speeds of approximately 75 mph — the equivalent of a Category 1 hurricane, CNN reported.

The storm was about 600 miles south-southeast of Okinawa with wind speeds clocking at 100 mph Wednesday. By Thursday, Kong-rey is expected to pass over Japan’s Ryukyu Islands, which are still dealing with the impacts from Typhoon Trami last weekend.

Taiwan and China are not in Kong-rey’s path, but parts of South Korea could be impacted.

Japan is still reeling from last month’s devastation of Typhoon Jebi, one of the strongest typhoons to hit the mainland in 25 years.

At least 11 died from the impacts of Jebi, and massive flooding caused the Kansai International Airport near Osaka to be closed for nearly one month.

How Liquefaction Made Mud Flow ‘Like Waves’ in Indonesia’s Earthquake Disaster

When a devastating earthquake and tsunami struck central Sulawesi, Indonesia on Friday, survivors found even the ground beneath their feet offered no safety: it had turned to liquid.

Many who attempted to find shelter were trapped by waves of earth that churned like water, the result of an earthquake process known as liquefaction.

“The ground rose up like a spine and suddenly fell. Many people were trapped and buried under collapsed houses. I could do nothing to help,” one survivor told the Associated Press this week.

The official death toll from the twin disasters — a 7.5-magnitude earthquake that triggered a tsunami — surpassed 1400 on Wednesday. But officials expect the number to rise as rescue workers dig more bodies from under collapsed buildings.

Much of the damage was wreaked by liquefaction. In one neighborhood, an estimated 1,700 houses were consumed by the roiling earth, according to Indonesia’s national rescue agency.

Here’s what to know about the nightmarish phenomenon:

What is liquefaction?

The U.S. Geological Survey explains liquefaction as a process that occurs when water-saturated soil, shaken by an earthquake, acts like a liquid. The ground temporarily loses its ability to bear structures like buildings or homes, often with deadly results.

Earthquake tremors can cause the water-logged soil to oscillate like waves, flow down inclined slopes, or be ejected upward in formations called “sand boils.”

Liquefaction also often causes the ground to settle unevenly, which can upset roads, bridges, pipelines and other infrastructure.

Where does it happen?

Areas near bays or marshland that were filled with dredged or reclaimed land are most vulnerable to liquefaction, according to the U.S.G.S. Land that is made of loose, granular sediment like sand is also highly susceptible.

Liquefaction has been observed during other major earthquakes, such as during the 1989 Loma Prieta earthquake in California, or the during the 1948 Fukui earthquake in Japan, when an estimated 67,000 homes were destroyed and 3,894 people were killed.

Why was it so damaging?
Conditions for liquefaction were ripe in Palu, the seaside town that bore the brunt of Indonesia’s recent disasters. Palu sits at the end of a bay, and is surrounded by a river delta.

Videos of the earthquake in action show buildings crumbling or even more unnervingly, pitching across the ground as if bucked by waves. Trees and telephone poles were uprooted and sent flying, or else consumed by the roiling soil.

“When the quake hit, the layers below the surface of the earth became muddy and loose,” Sutopo Purwo Nugroho, the spokesperson for Indonesia’s national rescue agency, told Reuters.

Among the victims were 34 children attending a Bible study camp, who were killed when their church collapsed from liquefaction, according to a Red Cross official.

Another 2,000 people are feared dead in Petobo, south of Palu, after a quake-triggered mudslide washed away homes, the Jakarta Post reported Monday. Local residents said the mud flowed “like waves,” according to the Post.

A Wrench In Earth’s Engine

Researchers at CU Boulder report that they may have solved a geophysical mystery, pinning down the likely cause of a phenomenon that resembles a wrench in the engine of the planet.

In a study published today in Nature Geoscience, the team explored the physics of “stagnant slabs.” These geophysical oddities form when huge chunks of Earth’s oceanic plates are forced deep underground at the edges of certain continental plates. The chunks sink down into the planet’s interior for hundreds of miles until they suddenly—and for reasons scientists can’t explain—stop like a stalled car.

CU Boulder’s Wei Mao and Shijie Zhong, however, may have found the reason for that halt. Using computer simulations, the researchers examined a series of stagnant slabs in the Pacific Ocean near Japan and the Philippines. They discovered that these cold rocks seem to be sliding on a thin layer of weak material lying at the boundary of the planet’s upper and lower mantle—roughly 660 kilometers, or 410 miles, below the surface.

And the stoppage is likely temporary: “Although we see these slabs stagnate, they are a fairly recent phenomena, probably happening in the last 20 million years,” said Zhong, a co-author of the new study and a professor in CU Boulder’s Department of Physics.

The findings matter for tectonics and volcanism on the Earth’s surface. Zhong explained that the planet’s mantle, which lies above the core, generates vast amounts of heat. To cool the globe down, hotter rocks rise up through the mantle and colder rocks sink.

“You can think of this mantle convection as a big engine that drives all of what we see on Earth’s surface: earthquakes, mountain building, plate tectonics, volcanos and even Earth’s magnetic field,” Zhong said.

The existence of stagnant slabs, which geophysicists first located about a decade ago, however, complicates that metaphor, suggesting that Earth’s engine may grind to a halt in some areas. That, in turn, may change how scientists think diverse features, such as East Asia’s roiling volcanos, form over geologic time.

Scientists have mostly located such slabs in the western Pacific Ocean, specifically off the east coast of Japan and deep below the Mariana Trench. They occur at the sites of subduction zones, or areas where oceanic plates at the surface of the planet plunge hundreds of miles below ground.

Slabs seen at similar sites near North and South America behave in ways that geophysicists might expect: They dive through Earth’s upper mantle and into the lower mantle where they heat up near the core.

But around Asia, “they simply don’t go down,” Zhong said. Instead, the slabs spread out horizontally near the boundary between the upper and lower mantle, a point at which heat and pressure inside Earth cause minerals to change from one phase to another.

To find out why slabs go stagnant, Zhong and Mao, a graduate student in physics, developed realistic simulations of how energy and rock cycle around the entire planet.

They found that the only way they could explain the behavior of the stagnant slabs was if a thin layer of less-viscous rock was wedged in between the two halves of the mantle. While no one has directly observed such a layer, researchers have predicted that it exists by studying the effects of heat and pressure on rock.

If it does, such a layer would act like a greasy puddle in the middle of the planet. “If you introduce a weak layer at that depth, somehow the reduced viscosity helps lubricate the region,” Zhong said. “The slabs get deflected and can keep going for a long distance horizontally.”

Stagnant slabs seem to occur off the coast of Asia, but not the Americas, because the movement of the continents above gives those chunks of rock more room to slide. Zhong, however, said that he doesn’t think the slabs will stay stuck. With enough time, he suspects that they will break through the slick part of the mantle and continue their plunge toward the planet’s core.

The planet, in other words, would still behave like an engine—just with a few sticky spots. “New research suggests that the story may be more complicated than we previously thought,” Zhong said.

Astronomers Find First Compelling Evidence For A Moon Outside Our Solar System

A pair of Columbia University astronomers using NASA’s Hubble Space Telescope and Kepler Space Telescope have assembled compelling evidence for the existence of a moon orbiting a gas-giant planet 8,000 light-years away.

In a paper published Oct. 3 in the journal Science Advances, Alex Teachey and David Kipping report that the detection of a candidate exomoon—that is, moons orbiting planets in other star systems—is unusual because of its large size, comparable to the diameter of Neptune. Such gargantuan moons do not exist in our own solar system, where nearly 200 natural satellites have been cataloged.

“This would be the first case of detecting a moon outside our solar system,” said Kipping, an assistant professor of astronomy at Columbia. “If confirmed by follow-up Hubble observations, the finding could provide vital clues about the development of planetary systems and may cause experts to revisit theories of how moons form around planets.”

In looking for exomoons, the researchers analyzed data from 284 Kepler-discovered planets that were in comparatively wide orbits, with periods greater than 30 days, around their host star. The observations measured the momentary dimming of starlight as a planet passed in front of its star, called a transit. The researchers found one instance, in Kepler 1625b, that had intriguing anomalies.

“We saw little deviations and wobbles in the light curve that caught our attention,” Kipping said.

The Kepler results were enough for the team to get 40 hours of time with Hubble to intensively study the planet, obtaining data four times more precise than that of Kepler. The researchers monitored the planet before and during its 19-hour-long transit across the face of the star. After it ended, Hubble detected a second and much smaller decrease in the star’s brightness 3.5 hours later, consistent with “a moon trailing the planet like a dog following its owner on a leash,” Kipping said. “Unfortunately, the scheduled Hubble observations ended before the complete transit of the moon could be measured.”

In addition to this dip in light, Hubble provided supporting evidence for the moon hypothesis by measuring that the planet began its transit 1.25 hours earlier than predicted. This is consistent with the planet and moon orbiting a common center of gravity (barycenter) that would cause the planet to wobble from its predicted location.

“An extraterrestrial civilization watching the Earth and Moon transit the Sun would note similar anomalies in the timing of Earth’s transit,” Kipping said.

The researchers note that in principle this anomaly could be caused by the gravitational pull of a hypothetical second planet in the system, although Kepler found no evidence for additional planets around the star during its four-year mission.

“A companion moon is the simplest and most natural explanation for the second dip in the light curve and the orbit-timing deviation,” said lead author Teachey, NSF Graduate Fellow in astronomy at Columbia. “It was a shocking moment to see that light curve, my heart started beating a little faster and I just kept looking at that signature. But we knew our job was to keep a level head testing every conceivable way in which the data could be tricking us until we were left with no other explanation.”

The moon is estimated to be only 1.5 percent the mass of its companion planet, which itself estimated to be several times the mass of Jupiter. This value is close to the mass-ratio between the Earth and its moon. But in the case of the Earth-Moon system and the Pluto-Charon system—the largest of the five known natural satellites of the dwarf planet Pluto—an early collision with a larger body is hypothesized to have blasted off material that later coalesced into a moon. Kepler 1625b and its satellite, however, are gaseous, not rocky, and, therefore, such a collision may not lead to the condensation of a satellite.

Exomoons are difficult to find because they are smaller than their companion planet and so their transit signal is weak; they also shift position with each transit because the moon is orbiting the planet. In addition, the ideal candidate planets hosting moons are in large orbits, with long and infrequent transit times. In this search, the Neptune-sized moon would have been among the easiest to first detect because of its large size.

The host planet and its moon lie within the solar mass star’s (Kepler 1625) habitable zone, where moderate temperatures allow for the existence of liquid water on any solid planetary surface. “Both bodies, however, are considered to be gaseous and therefore unsuitable for life as we know it,” Kipping said.

Future searches will target Jupiter-sized planets that are farther from their star than Earth is from the Sun. There are just a handful of these in the Kepler database. NASA’s upcoming James Webb Space Telescope could really “clean-up” in the satellite search, Kipping said. “We can expect to see really tiny moons.”

Black Holes Ruled Out As Universe’s Missing Dark Matter

For one brief shining moment after the 2015 detection of gravitational waves from colliding black holes, astronomers held out hope that the universe’s mysterious dark matter might consist of a plenitude of black holes sprinkled throughout the universe.

University of California, Berkeley, physicists have dashed those hopes.

Based on a statistical analysis of 740 of the brightest supernovas discovered as of 2014, and the fact that none of them appear to be magnified or brightened by hidden black hole “gravitational lenses,” the researchers concluded that primordial black holes can make up no more than about 40 percent of the dark matter in the universe. Primordial black holes could only have been created within the first milliseconds of the Big Bang as regions of the universe with a concentrated mass tens or hundreds of times that of the sun collapsed into objects a hundred kilometers across.

The results suggest that none of the universe’s dark matter consists of heavy black holes, or any similar object, including massive compact halo objects, so-called MACHOs.

Dark matter is one of astronomy’s most embarrassing conundrums: despite comprising 84.5 percent of the matter in the universe, no one can find it. Proposed dark matter candidates span nearly 90 orders of magnitude in mass, from ultralight particles like axions to MACHOs.

Several theorists have proposed scenarios in which there are multiple types of dark matter. But if dark matter consists of several unrelated components, each would require a different explanation for its origin, which makes the models very complex.

“I can imagine it being two types of black holes, very heavy and very light ones, or black holes and new particles. But in that case one of the components is orders of magnitude heavier than the other, and they need to be produced in comparable abundance. We would be going from something astrophysical to something that is truly microscopic, perhaps even the lightest thing in the universe, and that would be very difficult to explain,” said lead author Miguel Zumalacárregui, a Marie Curie Global Fellow at the Berkeley Center for Cosmological Physics.

An as-yet unpublished reanalysis by the same team using an updated list of 1,048 supernovas cuts the limit in half, to a maximum of about 23 percent, further slamming the door on the dark matter-black hole proposal.

“We are back to the standard discussions. What is dark matter? Indeed, we are running out of good options,” said Uroš Seljak, a UC Berkeley professor of physics and astronomy and BCCP co-director. “This is a challenge for future generations.”

The analysis is detailed in a paper published this week in the journal Physical Review Letters.

Dark matter lensing

Their conclusions are based on the fact that an unseen population of primordial black holes, or any massive compact object, would gravitationally bend and magnify light from distant objects on its way to Earth. Therefore, gravitational lensing should affect the light from distant Type Ia supernovas. These are the exploding stars that scientists have used as standard brightness sources to measure cosmic distances and document the expansion of the universe.

Zumalacárregui conducted a complex statistical analysis of data on the brightness and distance supernovas catalogued in two compilations — 580 in the Union and 740 in the joint light-curve analysis (JLA) catalogs — and concluded that eight should be brighter by a few tenths of a percent than predicted based on observations of how these supernovas brighten and fade over time. No such brightening has been detected.

Other researchers have performed similar but simpler analyses that yielded inconclusive results. But Zumalacárregui incorporated the precise probability of seeing all magnifications, from small to huge, as well as uncertainties in brightness and distance of each supernova. Even for low-mass black holes — those 1 percent the mass of the sun — there should be some highly magnified distant supernovas, he said, but there are none.

“You cannot see this effect on one supernova, but when you put them all together and do a full Bayesian analysis you start putting very strong constraints on the dark matter, because each supernova counts and you have so many of them,” Zumalacárregui said. The more supernovas included in the analysis, and the farther away they are, the tighter the constraints. Data on 1,048 bright supernovas from the Pantheon catalog provided an even lower upper limit — 23 percent — than the newly published analysis.

Seljak published a paper proposing this type of analysis in the late 1990s, but when interest shifted from looking for big objects, MACHOs, to looking for fundamental particles, in particular weakly interacting massive particles, or WIMPs, follow-up plans fell by the wayside. By then, many experiments had excluded most masses and types of MACHOs, leaving little hope of discovering such objects.

At the time, too, only a small number of distant Type Ia supernovas had been discovered and their distances measured.

Only after the LIGO observations brought up the issue again did Seljak and Zumalacárregui embark on the complicated analysis to determine the limits on dark matter.

“What was intriguing is that the masses of the black holes in the LIGO event were right where black holes had not yet been excluded as dark matter,” Seljak said. “That was an interesting coincidence that got everyone excited. But it was a coincidence.”

New Extremely Distant Solar System Object Found During Hunt For Planet X

Carnegie’s Scott Sheppard and his colleagues — Northern Arizona University’s Chad Trujillo, and the University of Hawaii’s David Tholen — are once again redefining our Solar System’s edge. They discovered a new extremely distant object far beyond Pluto with an orbit that supports the presence of an even-farther-out, Super-Earth or larger Planet X.

The newly found object, called 2015 TG387, will be announced Tuesday by the International Astronomical Union’s Minor Planet Center. A paper with the full details of the discovery has also been submitted to the Astronomical Journal.

2015 TG387 was discovered about 80 astronomical units (AU) from the Sun, a measurement defined as the distance between Earth and the Sun. For context, Pluto is around 34 AU, so 2015 TG387 is about two and a half times further away from the Sun than Pluto is right now.

The new object is on a very elongated orbit and never comes closer to the Sun, a point called perihelion, than about 65 AU. Only 2012 VP113 and Sedna at 80 and 76 AU respectively have more-distant perihelia than 2015 TG387. Though 2015 TG387 has the third-most-distant perihelion, its orbital semi-major axis is larger than 2012 VP113 and Sedna’s, meaning it travels much farther from the Sun than they do. At its furthest point, it reaches all the way out to about 2,300 AU. 2015 TG387 is one of the few known objects that never comes close enough to the Solar System’s giant planets, like Neptune and Jupiter, to have significant gravitational interactions with them.

“These so-called Inner Oort Cloud objects like 2015 TG387, 2012 VP113, and Sedna are isolated from most of the Solar System’s known mass, which makes them immensely interesting,” Sheppard explained. “They can be used as probes to understand what is happening at the edge of our Solar System.”

The object with the most-distant orbit at perihelion, 2012 VP113, was also discovered by Sheppard and Trujillo, who announced that find in 2014. The discovery of 2012 VP113 led Sheppard and Trujillo to notice similarities of the orbits of several extremely distant Solar System objects, and they proposed the presence of an unknown planet several times larger than Earth — sometimes called Planet X or Planet 9 — orbiting the Sun well beyond Pluto at hundreds of AUs.

“We think there could be thousands of small bodies like 2015 TG387 out on the Solar System’s fringes, but their distance makes finding them very difficult,” Tholen said. “Currently we would only detect 2015 TG387 when it is near its closest approach to the Sun. For some 99 percent of its 40,000-year orbit, it would be too faint to see.”

The object was discovered as part of the team’s ongoing hunt for unknown dwarf planets and Planet X. It is the largest and deepest survey ever conducted for distant Solar System objects.

“These distant objects are like breadcrumbs leading us to Planet X. The more of them we can find, the better we can understand the outer Solar System and the possible planet that we think is shaping their orbits — a discovery that would redefine our knowledge of the Solar System’s evolution,” Sheppard added.

It took the team a few years of observations to obtain a good orbit for 2015 TG387 because it moves so slowly and has such a long orbital period. They first observed 2015 TG387 in October of 2015 at the Japanese Subaru 8-meter telescope located atop Mauna Kea in Hawaii. Follow-up observations at the Magellan telescope at Carnegie’s Las Campanas Observatory in Chile and the Discovery Channel Telescope in Arizona were obtained in 2015, 2016, 2017 and 2018 to determine 2015 TG387’s orbit.

2015 TG387 is likely on the small end of being a dwarf planet since it has a diameter near 300 kilometers. The location in the sky where 2015 TG387 reaches perihelion is similar to 2012 VP113, Sedna, and most other known extremely distant trans-Neptunian objects, suggesting that something is pushing them into similar types of orbits.

Trujillo and University of Oklahoma’s Nathan Kaib ran computer simulations for how different hypothetical Planet X orbits would affect the orbit of 2015 TG387. The simulations included a Super-Earth-mass planet at several hundred AU on an elongated orbit as proposed by Caltech’s Konstantin Batygin and Michael Brown in 2016. Most of the simulations showed that not only was 2015 TG387’s orbit stable for the age of the Solar System, but it was actually shepherded by Planet X’s gravity, which keeps the smaller 2015 TG387 away from the massive planet. This gravitational shepherding could explain why the most-distant objects in our Solar System have similar orbits. These orbits keep them from ever approaching the proposed planet too closely, which is similar to how Pluto never gets too close to Neptune even though their orbits cross.

“What makes this result really interesting is that Planet X seems to affect 2015 TG387 the same way as all the other extremely distant Solar System objects. These simulations do not prove that there’s another massive planet in our Solar System, but they are further evidence that something big could be out there” Trujillo concludes.

This research was funded by NASA Planetary Astronomy grant NNX15AF44G.

Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. These results made use of the Discovery Channel Telescope at Lowell Observatory. Lowell is a private, non-profit institution dedicated to astrophysical research and public appreciation of astronomy and operates the DCT in partnership with Boston University, the University of Maryland, the University of Toledo, Northern Arizona University and Yale University. These results used the Large Monolithic Imager, which was built by Lowell Observatory using funds provided by the National Science Foundation (AST-1005313). This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.