Scientists get first glimpse of black hole eating star, ejecting high-speed flare

This artists impression shows a black hole consuming a star that has been torn apart by the black hole's strong gravity. As a result of this massive "meal" the black hole begins to launch a powerful jet that we can detect with radio telescopes.

An international team of astrophysicists led by a Johns Hopkins University scientist has for the first time witnessed a star being swallowed by a black hole and ejecting a flare of matter moving at nearly the speed of light.

The finding reported in the journal Science tracks the star -- about the size of our sun -- as it shifts from its customary path, slips into the gravitational pull of a supermassive black hole and is sucked in, said Sjoert van Velzen, a Hubble fellow at Johns Hopkins.

"These events are extremely rare," van Velzen said. "It's the first time we see everything from the stellar destruction followed by the launch of a conical outflow, also called a jet, and we watched it unfold over several months."

Black holes are areas of space so dense that irresistible gravitational force stops the escape of matter, gas and even light, rendering them invisible and creating the effect of a void in the fabric of space. Astrophysicists had predicted that when a black hole is force-fed a large amount of gas, in this case a whole star, then a fast-moving jet of plasma -- elementary particles in a magnetic field -- can escape from near the black hole rim, or "event horizon." This study suggests this prediction was correct, the scientists said.

"Previous efforts to find evidence for these jets, including my own, were late to the game," said van Velzen, who led the analysis and coordinated the efforts of 13 other scientists in the United States, the Netherlands, Great Britain and Australia.

Supermassive black holes, the largest of black holes, are believed to exist at the center of most massive galaxies. This particular one lies at the lighter end of the supermassive black hole spectrum, at only about a million times the mass of our sun, but still packing the force to gobble a star.

The first observation of the star being destroyed was made by a team at the Ohio State University, using an optical telescope in Hawaii. That team announced its discovery on Twitter in early December 2014.

After reading about the event, van Velzen contacted an astrophysics team led by Rob Fender at the University of Oxford in Great Britain. That group used radio telescopes to follow up as fast as possible. They were just in time to catch the action.

By the time it was done, the international team had data from satellites and ground-based telescopes that gathered X-ray, radio and optical signals, providing a stunning "multi-wavelength" portrait of this event.

It helped that the galaxy in question is closer to Earth than those studied previously in hopes of tracking a jet emerging after the destruction of a star. This galaxy is about 300 million light years away, while the others were at least three times farther away. One light year is 5.88 trillion miles.

The first step for the international team was to rule out the possibility that the light was from a pre-existing expansive swirling mass called an "accretion disk" that forms when a black hole is sucking in matter from space. That helped to confirm that the sudden increase of light from the galaxy was due to a newly trapped star.

"The destruction of a star by a black hole is beautifully complicated, and far from understood," van Velzen said. "From our observations, we learn the streams of stellar debris can organize and make a jet rather quickly, which is valuable input for constructing a complete theory of these events."

Van Velzen last year completed his doctoral dissertation at Radboud University in the Netherlands, where he studied jets from supermassive black holes. In the last line of the dissertation, he expressed his hope to discover these events within four years. It turned out to take only a few months after the ceremony for his dissertation defense.

Van Velzen and his team were not the only ones to hunt for radio signals from this particular unlucky star. A group at Harvard observed the same source with radio telescopes in New Mexico and announced its results online. Both teams presented results at a workshop in Jerusalem in early November. It was the first time the two competing teams had met face to face.

"The meeting was an intense, yet very productive exchange of ideas about this source," van Velzen said. "We still get along very well; I actually went for a long hike near the Dead Sea with the leader of the competing group."

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The above post is reprinted from materials provided by Johns Hopkins University. Note: Materials may be edited for content and length.

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Journal Reference:

1. S. van Velzen, G. E. Anderson, N. C. Stone, M. Fraser, T. Wevers, B. D. Metzger, P. G. Jonker, A. J. van der Horst, T. D. Staley, A. J. Mendez, J. C. A. Miller-Jones, S. T. Hodgkin, H. C. Campbell, R. P. Fender. A radio jet from the optical and X-ray bright stellar tidal disruption flare ASASSN-14li. Science, 2015; DOI: 10.1126/science.aad1182

To see or not to see: Answering questions about neurons

A thalamocortical, or TC neuron labeled with fluorescent dye, as used in Dr. Augustinaite’s study. The image shows a voltage recording device, at bottom left, entering the yellow cell body, and a stimulation device, at top, reaching the dendrites. Color in this image shows the depth in the slice.

The brain is a complicated network of small units called neurons, all working to carry information from the outside world, create an internal model, and generate a response. Neurons sense a signal through branching dendrites, carry this signal to the cell body, and send it onwards through a long axon to signal the next neuron. However, neurons can function in many different ways; some of which researchers are still exploring. Some signals that the dendrites receive do not continue to the next neuron; instead they seem to change the way that the neuron handles the subsequent signals. This could help neurons function as part of a large network, but researchers still have many questions. Dr. Sigita Augustinaite, a researcher in the Optical Neuroimaging Unit at the Okinawa Institute of Science and Technology Graduate University, suggested one mechanism explaining how neurons help the network function. Her findings, part of collaboration between the University of Oslo and OIST, were published August 13, 2014 as the cover article in The Journal of Neuroscience.

Dr. Augustinaite studies the visual pathway, where signals from the retina are sent to the visual cortex, where the brain interprets signals from the eye. Between the eye and the visual cortex, the signals must pass through the visual thalamus, that is, through thalamocortical, or TC neurons. These neurons can switch between a “sleeping” state and a “waking” state depending on input they receive from neurons and other brain areas. When an animal is awake, TC neurons transmit the incoming retinal signals on to the cortex, but when the animal is asleep, the neurons block retinal signals.

The visual cortex also sends a massive input back to TC neurons to control retinal signals traveling through the thalamus. But Dr. Augustinaite says that the suggested mechanisms of this control bring more questions than answers. To understand more, she conducted experiments in acute brain slices, small pieces of brain tissue where neurons stay alive and maintain their physiological properties. She added glutamate to dendrites far from the cell body to emulate a feedback signal from the visual cortex. Then she measured the neuron’s response, shown as a voltage difference between inside and outside of the membrane.

Dr. Augustinaite found that stimulating the neurons in this way depolarizes their membranes, creating something called NMDA spike/plateau potentials. If strong enough, depolarization can cause a neuron to fire an action potential, which travels through the axon to activate other neurons. Action potentials look like a sharp, one-millisecond increase in membrane voltage, and they transmit signals from retina to cortex. But if NMDA spike/plateaus induces action potentials, signals from the cortex and signals from the retina would be indistinguishable. With her experiments, Dr. Augustinaite showed that the NMDA spike/plateau potentials in TC neurons do not trigger action potentials. Instead, they lift the voltage of the membrane, changing the neuron’s properties for few hundred milliseconds, creating conditions for reliable signal transmission from retina to cortex.

“The research gives, for the first time, a clear view on what dendritic potentials are good for,” explained Prof. Bernd Kuhn, who leads the lab where Dr. Augustinaite works. “It points directly to the mechanism,” he concluded. Showing how dendritic plateaus function is just one important step toward understanding how neurons function as a network. “This mechanism could also be used in many other neuronal circuits, where one input regulates how another input moves through the network,” Dr. Augustinaite said. “This mechanism is an exciting logical element in the neuronal network, but just the start of putting the puzzle together.”

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Story Source:

The above post is reprinted from materials provided byOkinawa Institute of Science and Technology - OIST. The original item was written by Poncie Rutsch. Note: Materials may be edited for content and length.

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Journal Reference:

1. Sigita Augustinaite, Bernd Kuhn, Paul Johannes Helm, And Paul Heggelund. NMDA Spike/Plateau Potentials in Dendrites of Thalamocortical Neurons. The Journal of Neuroscience, September 2014 DOI:10.1523/JNEUROSCI.1205-13.2014

Sensor sees nerve action as it happens

Researchers at Duke and Stanford Universities have devised a way to watch the details of neurons at work, pretty much in real time.

Every second of every day, the 100 billion neurons in your brain are capable of firing off a burst of electricity called an action potential up to 100 times per second. For neurologists trying to study how this overwhelming amount of activity across an entire brain translates into specific thoughts and behaviors, they need a faster way to watch.

Existing techniques for monitoring neurons are too slow or too tightly focused to generate a holistic view. But in a new study, researchers reveal a technique for watching the brain's neurons in action with a time resolution of about 0.2 milliseconds -- a speed just fast enough to capture the action potentials in mammalian brains.

The paper appeared early online in Science.

"We set out to combine a protein that can quickly sense neural voltage potentials with another protein that can amplify its signal output," said Yiyang Gong, assistant professor of biomedical engineering at Duke and first author on the paper. "The resulting increase in sensor speed matches what is needed to read out electrical spikes in the brains of live animals."

Gong did the work as a postdoctoral fellow in the laboratory of Mark Schnitzer, associate professor of biological sciences and applied physics at Stanford, and an investigator of the Howard Hughes Medical Institute. Gong and his colleagues sought out a voltage sensor fast enough to keep up with neurons. After several trials, the group landed on one found in algae, and engineered a version that is both sensitive to voltage activity and responds to the activity very quickly.

The amount of light it puts out, however, wasn't bright enough to be useful in experiments. It needed an amplifier.

To meet this engineering challenge, Gong fused the newly engineered voltage sensor to the brightest fluorescing protein available at the time. He linked the two close enough to interact optically without slowing the system down.

"When the voltage sensing component we engineered detects a voltage potential, it absorbs more light," explained Gong. "And by absorbing more of the bright fluorescent protein's light, the overall fluorescence of the system dims in response to a neuron firing."

The new sensor was delivered to the brains of mice using a virus and incorporated into fruit flies through genetic modification. In both cases, the researchers were able to express the protein in selected neurons and observe voltage activity. They were also able to read voltage movements in different sub-compartments of individual neurons, which is very difficult to do with other techniques.

"Being able to read voltage spikes directly from the brain and also see their specific timing is very helpful in determining how brain activity drives animal behavior," said Gong. "Our hope is that the community will explore those types of questions in more detail using this particular sensor. Already I've received multiple emails from groups interested in trying the technique in their own labs."

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1. Yiyang Gong, Cheng Huang, Jin Zhong Li, Benjamin F. Grewe, Yanping Zhang, Stephan Eismann, Mark J. Schnitzer. High-speed recording of neural spikes in awake mice and flies with a fluorescent voltage sensor. Science, November 2015 DOI:10.1126/science.aab0810

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The above post is reprinted from materials provided by Duke University. The original item was written by Ken Kingery. Note: Materials may be edited for content and length.

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Eight new planets found in 'Goldilocks' zone: Two are most similar to Earth of any known exoplanets

This artist's conception depicts an Earth-like planet orbiting an evolved star that has formed a stunning "planetary nebula." Earlier in its life, this planet may have been like one of the eight newly discovered worlds orbiting in the habitable zones of their stars.

Astronomers announced today that they have found eight new planets in the "Goldilocks" zone of their stars, orbiting at a distance where liquid water can exist on the planet's surface. This doubles the number of small planets (less than twice the diameter of Earth) believed to be in the habitable zone of their parent stars. Among these eight, the team identified two that are the most similar to Earth of any known exoplanets to date.

"Most of these planets have a good chance of being rocky, like Earth," says lead author Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics (CfA).

These findings were announced today at a meeting of the American Astronomical Society.

The two most Earth-like planets of the group are Kepler-438b and Kepler-442b. Both orbit red dwarf stars that are smaller and cooler than our Sun. Kepler-438b circles its star every 35 days, while Kepler-442b completes one orbit every 112 days.

With a diameter just 12 percent bigger than Earth, Kepler-438b has a 70-percent chance of being rocky, according to the team's calculations. Kepler-442b is about one-third larger than Earth, but still has a 60-percent chance of being rocky.

To be in the habitable zone, an exoplanet must receive about as much sunlight as Earth. Too much, and any water would boil away as steam. Too little, and water will freeze solid.

"For our calculations we chose to adopt the broadest possible limits that can plausibly lead to suitable conditions for life," says Torres.

Kepler-438b receives about 40 percent more light than Earth. (In comparison, Venus gets twice as much solar radiation as Earth.) As a result, the team calculates it has a 70 percent likelihood of being in the habitable zone of its star.

Kepler-442b get about two-thirds as much light as Earth. The scientists give it a 97 percent chance of being in the habitable zone.

"We don't know for sure whether any of the planets in our sample are truly habitable," explains second author David Kipping of the CfA. "All we can say is that they're promising candidates."

Prior to this, the two most Earth-like planets known were Kepler-186f, which is 1.1 times the size of Earth and receives 32 percent as much light, and Kepler-62f, which is 1.4 times the size of Earth and gets 41 percent as much light.

The team studied planetary candidates first identified by NASA's Kepler mission. All of the planets were too small to confirm by measuring their masses. Instead, the team validated them by using a computer program called BLENDER to determine that they are statistically likely to be planets. BLENDER was developed by Torres and colleague Francois Fressin, and runs on the Pleaides supercomputer at NASA Ames. This is the same method that has been used previously to validate some of Kepler's most iconic finds, including the first two Earth-size planets around a Sun-like star and the first exoplanet smaller than Mercury.

After the BLENDER analysis, the team spent another year gathering follow-up observations in the form of high-resolution spectroscopy, adaptive optics imaging, and speckle interferometry to thoroughly characterize the systems.

Those follow-up observations also revealed that four of the newly validated planets are in multiple-star systems. However, the companion stars are distant and don't significantly influence the planets.

As with many Kepler discoveries, the newly found planets are distant enough to make additional observations challenging. Kepler-438b is located 470 light-years from Earth while the more distant Kepler-442b is 1,100 light-years away.

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The above post is reprinted from materials provided byHarvard-Smithsonian Center for Astrophysics. Note: Materials may be edited for content and length.

Radiation blasts leave most Earth-like planet uninhabitable

The planet Kepler-438b is shown here in front of its violent parent star. It is regularly irradiated by huge flares of radiation, which could render the planet uninhabitable. Here the planet's atmosphere is shown being stripped away.

The most Earth-like planet could have been made uninhabitable by vast quantities of radiation, new research led by the University of Warwick research has found.

The atmosphere of the planet, Kepler-438b, is thought to have been stripped away as a result of radiation emitted from a superflaring Red Dwarf star, Kepler-438.

Regularly occurring every few hundred days, the superflares are approximately ten times more powerful than those ever recorded on the Sun and equivalent to the same energy as 100 billion megatons of TNT.

While superflares themselves are unlikely to have a significant impact on Kepler-438b's atmosphere, a dangerous phenomenon associated with powerful flares, known as a coronal mass ejection (CME), has the potential to strip away any atmosphere and render it uninhabitable.

The planet Kepler-438b, to date the exoplanet with the highest recorded Earth Similarity Index, is both similar in size and temperature to the Earth but is in closer proximity to the Red Dwarf than the Earth is to the Sun.

Lead researcher, Dr David Armstrong of the University of Warwick's Astrophysics Group, explains:

"Unlike the Earth's relatively quiet sun, Kepler-438 emits strong flares every few hundred days, each one stronger than the most powerful recorded flare on the Sun. It is likely that these flares are associated with coronal mass ejections, which could have serious damaging effects on the habitability of the planet.

"If the planet, Kepler-438b, has a magnetic field like the Earth, it may be shielded from some of the effects. However, if it does not, or the flares are strong enough, it could have lost its atmosphere, be irradiated by extra dangerous radiation and be a much harsher place for life to exist."

Discussing the impact of the superflares and radiation on the atmosphere of Kepler-438b, Chloe Pugh, of the University of Warwick's Centre for Fusion, Space and Astrophysics, says:

"The presence of an atmosphere is essential for the development of life. While flares themselves are unlikely to have a significant impact on an atmosphere as a whole, there is another more dangerous phenomenon associated with powerful flares, known as a coronal mass ejection.

"Coronal mass ejections are where a huge amount of plasma is hurled outwards from the Sun, and there is no reason why they should not occur on other active stars as well. The likelihood of a coronal mass ejection occurring increases with the occurrence of powerful flares, and large coronal mass ejections have the potential to strip away any atmosphere that a close-in planet like Kepler-438b might have, rendering it uninhabitable. With little atmosphere, the planet would also be subject to harsh UV and X-ray radiation from the superflares, along with charged particle radiation, all of which are damaging to life."

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Story Source:

The above post is reprinted from materials provided byUniversity of Warwick. Note: Materials may be edited for content and length.

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Journal Reference:

1. D. J. Armstrong, C. E. Pugh, A.-M. Broomhall, D. J. A. Brown, M. N. Lund, H. P. Osborn, D. L. Pollacco. The Host Stars of Keplers Habitable Exoplanets: Superflares, Rotation and Activity. Monthly Notices of the Royal Astronomical Society, 2015 [link]

Cheaper, Higher Performing LEDs

A team of Florida State University materials researchers has developed a new type of light-emitting diode, or LED, using an organic-inorganic hybrid that could lead to cheaper, brighter and mass produced lights and displays in the future.

Assistant Professor of Physics Hanwei Gao and Associate Professor of Chemical Engineering Biwu Ma are using a class of materials called organometal halide perovskites to build a highly functioning LED. They lay out their findings in the journalAdvanced Materials.

"Early work suggested perovskites could be a promising material to build LEDs," Gao said. "But, the performance was not up to their potential. We believed there was significant room for improvement."

Perovskites are any materials with the same type of crystal structure as calcium titanium oxide. Other researchers experimented with perovskites to build LEDs in the past but could not build particularly effective ones. Gao and Ma believed this organic-inorganic hybrid could perform better, if the formula could be appropriately tweaked.

"When we thought about this class of material, we knew it should perform better than this," Ma said. "We came up with our novel approach to solve some critical problems and get a high-performance LED."

After months of experiments using synthetic chemistry to fine-tune the material properties and device engineering to control the device architectures, they ultimately created an LED that performed even better than expected. The material glowed exceptionally bright.

It is measured at about 10,000 candelas per square meter at a driving voltage of 12V -- candelas are the unit of measurement for luminescence. As a benchmark, LEDs glowing at about 400 candelas per square meter are sufficiently bright for computer screens.

"Such exceptional brightness is, to a large extent, owing to the inherent high luminescent efficiency of this surface-treated, highly crystalline nanomaterial," Gao said.

It was also quick and easy to produce.

Gao and Ma can produce the material in about an hour in the lab and have a full device created and tested in about half a day.

Additionally, while bare hybrid perovskites tend to be unstable in humid air, the nanostructured perovskites exhibit remarkable stability in ambient environment because of the purposely designed surface chemistry. Such chemical stability largely reduces the requirement of sophisticated infrastructure to produce this new type of LEDs and could be of huge benefit for cost-effective manufacturing in the future.

The research is crucial to the advance of LED technology, which is fast becoming an avenue to reduce the country's electric consumption. LED lighting is already sold in stores, but widespread adoption has been slow because of the costs associated with the material and the quality. But, LED lights do save energy.

According to the U.S. Department of Energy, residential LED lighting uses at least 75 percent less energy than regular incandescent lighting.

"If you can get a low cost, high performing LED, everyone will go for it," Ma said. "For industry, our approach has a big advantage in that earth abundant materials can be processed in an economic way to make the products."

Gao and Ma came to FSU as part of the Energy and Materials Strategic Initiative with the mission of producing high tech materials for new generation, energy sustainable technology. By chance, they wound up with offices next to each other and began collaborating.

They also work with Assistant Professor of Industrial and Manufacturing Engineering Zhibin Yu, who also focuses on LED technology research, as well as Assistant Professor of Chemistry Kenneth Hanson, who is a co-author on this current paper.

"Gao and Ma, as well as Ken Hanson, are members of a cohort of 11 new faculty hires in the Energy and Materials Strategic Hiring Initiative," said Associate Vice President for Research W. Ross Ellington. "The present work, as well as other recent, joint publications, indicates that the desired synergies are being achieved in this effort."

In addition to Gao and Ma, other FSU researchers involved with the experiments are Hanson, post-doctoral research associates Yichuan Ling and Zhao Yuan, and graduate students Yu Tian, Xi Wang and Jamie C. Wang.

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Story Source:

The above post is reprinted from materials provided by Florida State University. Note: Materials may be edited for content and length.

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Journal Reference:

1. Yichuan Ling, Zhao Yuan, Yu Tian, Xi Wang, Jamie C. Wang, Yan Xin, Kenneth Hanson, Biwu Ma, Hanwei Gao.Bright Light-Emitting Diodes Based on Organometal Halide Perovskite Nanoplatelets. Advanced Materials, 2015; DOI: 10.1002/adma.201503954

What's in a name? More than you think...

What's in a name? In the case of the usernames of video gamers, a remarkable amount of information about their real world personalities, according to research by psychologists at the University of York.

Analysis of anonymised data from one of the world's most popular computer games by scientists in the Department of Psychology at York also revealed information about their ages.

Professor Alex Wade and PhD student Athanasios Kokkinakis, a PhD student on the Engineering and Physical Sciences Research Council-funded Intelligent Games and Game Intelligence(IGGI) project, analysed data from League of Legends, a game played by around 70 million people worldwide..

The researchers say that mining of video game data could become an important area of research into the personalities of players, as well as potentially providing evidence of clinical disorders such as autism, sociopathy or addictive personality. The research is published in Computers in Human Behavior.

The developer of League of Legends, Riot Games provided 500,000 data points for the analysis. These anonymised data contained user names, information on the in-game behaviour of players and the reaction of other gamers -- the latter from the post-match 'Honour' and 'Report' feedback each player can file. The study is the first to use this methodology to examine player interaction in a multiplayer online battle arena (MOBA) game.

The researchers found that where a player incorporated a profanity or other anti-social expression in their user name, they tended to adopt similar anti-social behaviour in the game environment. Conversely, they found that positive in-game behaviour such as rapid learning, team building or leadership might correlate both with positive usernames and with positive personality traits in the real world.

The psychologists also discovered that where numbers featured in user names, it often provided an indication of the age of players.

Professor Wade said: "Video games can provide a wealth of useful population-level information on developmental, cognitive and psychological processes. We found that people who have anti-social names tend to behave in an anti-social way within the game. Younger people behave poorly and older people less so.

"This data is like a window on individual players' personalities so we believe that we might be able to use video games a way of testing people's personalities." Athanasios Kokkinakis added: "We think this is just the tip of the iceberg -- these massive datasets offer an unprecedented tool for studying human psychology across the globe."

The University of York leads the Digital Creativity (DC) Hub which aims to spark a revolution by harnessing cutting edge research in digital games and interactive media to benefit society. Funded by the Engineering and Physical Sciences Research Council, it is one of a network of six new multidisciplinary research centres that are driving forward the UK's Digital Economy research, knowledge and skills.

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1. Athanasios V. Kokkinakis, Jeff Lin, Davin Pavlas, Alex R. Wade. What's in a name? Ages and names predict the valence of social interactions in a massive online game. Computers in Human Behavior, 2016; 55: 605 DOI:10.1016/j.chb.2015.09.034

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The above post is reprinted from materials provided byUniversity of York. Note: Materials may be edited for content and length.

Journal Reference: