Tag Archives: black

Painting wind turbines black can help birds not fly into them

The white, sleek exterior of the wind turbine definitely looks good to me. But birds probably wouldn’t agree. According to a new paper, the current design of our wind turbines makes them hard to see for birds, promoting impacts.

Image credits Roel May et al., (2020), Ecology and Evolution.

Not only would such a change help save bird lives, but it would also help our bottom line. Birds in flight hit hard, and turbines are expensive to repair or replace. Taking one of them off for repairs also incurs costs (as they can’t produce power during the same time). All in all, the paper argues, painting one of the three rotor blades black is enough to help birds see the turbines and avoid collisions.

Seeing is avoiding

“As wind energy deployment increases and larger wind‐power plants are considered, bird fatalities through collision with moving turbine rotor blades are expected to increase. However, few (cost‐) effective deterrent or mitigation measures have so far been developed to reduce the risk of collision,” the authors explain in their paper.

“We tested the hypothesis that painting would increase the visibility of the blades, [which reduced bird fatalities] by over 70% relative to the neighboring control (i.e., unpainted) turbines.”

Growing awareness of climate change has prompted countries all over the world to move away from fossil fuels into clean energy sources; wind is a particular favorite, as wind farms can be installed in otherwise unusable (and quite unpleasant areas) such as windy coastal areas.

That isn’t to say, however, that wind energy is flawless. As with everything else in life, it comes with good and bad both. Although they won’t release CO2 and heat up the planet, turbines can be quite disturbing to wildlife as they’re quite noisy, they bring humans to the area, and they’re a significant collision risk for birds. We have procedures in place to ensure that the sites we choose for such farms pose the lowest possible risk to wildlife. However, as more and more wind capacity is being installed, it’s unavoidable that it will impact local animals.

The current paper tested whether painting one of the three rotor blades of each turbine can help lower collisions with birds. The experiment was carried out at the Smøla wind-power in Norway. The plant was built in two phases: 20 turbines of 2.1 MW were finished in September 2002, and an additional 48 turbines of 2.3 MW in August 2005. the team used trained dogs to look for bird carcasses in a radius of 100 m around the turbines “at regular intervals”.

Roughly 9,560 turbine searches were performed between 2006–2016, finding 464 carcasses. The team explains that “there was an average 71.9% reduction in the annual fatality rate after painting at the painted turbines relative to the control turbines”. Despite this, they note that annual fatalities fluctuated significantly. All in all, there is enough evidence to seriously consider this approach as an effective way to protect birds from impacts with wind turbines. However, more long-term research is needed to establish exactly how effective it is in absolute numbers.

“The in situ experiment was performed comparing only four treated turbines to the neighboring four untreated turbines. We must therefore be careful what we deduce from the experiment given the limited number of turbine pairs,” the authors note.

“However, the experiment ran over a long timeframe, encompassing seven and a half years pretreatment and three and a half years post‐treatment”

The paper “Paint it black: Efficacy of increased wind turbine rotor blade visibility to reduce avian fatalities” has been published in the journal Ecology and Evolution.

NASA releases beautiful new animation of a black hole

A beautiful new animation produced by NASA helps visualize the relationship between gravity, time, and space.

Image credits NASA Goddard Space Flight Center / Jeremy Schnittman.

Researchers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, have generated a new animation of a black hole and its surrounding matter disk. The animation is based on radio images of a black hole at the core of galaxy M87 taken by the Event Horizon Telescope.

Bendy time

“Simulations and movies like these really help us visualize what Einstein meant when he said that gravity warps the fabric of space and time,” says Jeremy Schnittman, Ph.D., the NASA astrophysicist who generated these gorgeous images using custom software

Schnittman’s work helps to showcase how the huge gravity around a black hole distorts the way we perceive its surroundings. That halo-like structure is, in fact, a disk. This accretion disk is a relatively thin mass of gas infalling into the black hole; we see it in the particular shape shown above because gravity is bending light around the black hole. It’s pretty similar to bending a picture of the disk.

Gas in accretion disks is very hot (through a combination of friction and compression), so it radiates in different parts of the electromagnetic spectrum. Those around the youngest of stars glow in infrared, but the disk in this animation glows with X-rays, because it has a lot of energy. It ripples and flows as magnetic fields move along its bulk. This creates brighter and dimmer bands in the disk.

The gas also moves faster the closer it gets to the black hole — close to the speed of light nearest to it. In the animation above, this makes the left side look brighter than the right side due to redshift.

The thin line of light that seemingly outlines the black hole is its “photon ring”. You’re actually looking at the underside of the disk, its image bent back to us by the massive gravitational pull there. What we see as the photon ring is made up of several layers that grow progressively thinner and dimmer — this is light that’s been bent several times around the black hole before escaping for our telescopes to capture. Schnittman’s model uses a spherical black hole, so here the photon ring looks identical from every angle.

“Until very recently, these visualizations were limited to our imagination and computer programs,” Schnittman says. “I never thought that it would be possible to see a real black hole.”

Plague extent.

Study reveals true scale of one of the world’s deadliest plagues

New research shows that one of the deadliest plagues in the world was even more far-reaching than previously believed.

Skull.

Image credits Alchemilla Mollis

The work was carried out by an interdisciplinary team from the Max Planck Institute for the Science of Human History in Germany and the Harvard University. They covered 21 archaeological sites across Europe and the Mediterranean that date back to the Plague of Justinian, back in 541 A.D. They report that the plague affected even more of the world than previously believed, reaching as far as the post-Roman British Isles.

Plagues for days

“This study shows the potential of paleogenomic research for understanding historical and modern pandemics by comparing genomes across millennia,” Johannes Krause, director of the Max Planck Institute and co-director of the Max Planck-Harvard Research Center for the Archaeoscience of the Ancient Mediterranean and the paper’s corresponding author, said in a statement.

This outbreak was one of the deadliest events in humanity’s history, killing an estimated 25-50 million people (between 13-26%) of the world’s population at the time of its first outbreak. It nearly brought the Byzantine Empire and its neighboring Sasanian Empire to the brink of collapse. Justinian’s Plague was the single deadliest pandemic to afflict Europe (and perhaps the world as a whole) until the Black Plague, and made repeated appearances until the year 750. The Black Death is estimated to have killed every 1 in 2 or 3 people living in Europe at the time. It was caused by the same bacteria.

The Justinian Plague gets its name from the Byzantine Emperor Justinian, who ruled the eastern portion of the Roman Empire from Constantinople (today’s Istanbul) after the fall of Rome and the western Empire. The pandemic started during the reign of Emperor Justinian, and spread from Constantinople and ports around the Mediterranean. Accounts from the time say that the plague wiped out half of Constantinople’s population, although these have yet to be confirmed. Such impacts are still under active investigation by historians, archaeologists, and experts in ancient DNA at the Max Planck-Harvard Research Center for the Archaeoscience of the Ancient Mediterranean (MHAAM). In the current study, the team reconstructed the genomes of eight Y. pestis strains from samples gathered in France, Germany, Spain, and Great Britain.

Geographic extent of the First Pandemic and sampled sites.
Image credits Marcel Keller et al., (2019), PNAS.

Samples that the team recovered at these sites were examined for genetic traces of Yersinia pestis, the bacteria known to have caused the plague. The first finding was the confirmation that this was the plague that swept the Mediterranean during Justinian’s time, even if it is recorded under various names in historical documents.

Secondly, the team could chart the evolution of the bacteria over time. They report that the strains that popped over the two-century-long pandemic were quite diverse genetically. Samples taken during the latter days of the pandemic show Y. pestis had shed genes relating to two virulence factors, they explain.

“It’s a fantastic example of how we can get new results that are really important in a debate that, kind of paradoxically, is heating up right now about whether the Justinianic pandemic was an important thing or not, just as new evidence really starts to appear,” says paper co-author McCormick.

“The archaeological and archaeogenetic evidence is opening up a whole new — not just a chapter — a whole new book on this great story.”

The team also found traces of the plague in Britain, an area where it hadn’t been previously confirmed. The bacterial DNA found there is more basal, the team explains, which suggests that it arrived there directly from areas where the plague was first reported — such as Egypt — rather than the Roman Empire.

“If that’s so,” McCormick said, “that suggests almost direct transmission from Egypt to Britain.”

This last tidbit is especially interesting. Given that the plague spread from and around the Mediterranean, one would assume that any Y. pestis in Britain would have been carried there by Romano-Celts moving into the islands after the Romans left, a century later. However, the team found the bacteria in an Anglo-Saxon cemetery, among people who were expanding their control of Britain at the time. The question now is how the four infected individuals in Britain contracted the plague — a finding which the team says will give us a better understanding of the social, political, and economic dynamics of the day.

McCormick said researchers will continue to expand the picture of this period, focusing on the role the plague played not just in human health, but, given its extraordinary death rate, also in warfare, politics, economics, and a whole host of other human activities.

“We now have a pathogen whose molecular history we can follow for thousands of years,” McCormick said, adding that our understanding of the plague’s impact on this era will continue to grow. “The jury’s out, evidence is accumulating, and we’re all going to learn as we go forward.”

The paper “Ancient Yersinia pestis genomes from across Western Europe reveal early diversification during the First Pandemic (541–750)” has been published in the journal PNAS.

Sagittarius A*

Researchers find black hole that spins almost as fast as (we think) they can spin

New research led by members from the University of Southampton has identified a black hole spinning around its axis near its maximum possible speed.

Sagittarius A*

A simulated image of supermassive black hole Sagittarius A*, showing against a background of radiation and bright matter swept into the event horizon. The image was generated with data recorded by the Event Horizon Telescope.
Image credits National Radio Astronomy Observatory,

The study involved an international team of astronomers. Starting from observations taken with state-of-the-art sensors, the researchers found evidence that 4U 1630-472, a stellar-mass black hole in our galaxy, is rotating really, really fast — around 92% to 95% of a black hole’s theoretical maximum rotational speed.

Material keeps falling into this black hole as its spinning, being subjected do immense gravitational stress and temperatures. The environment is so violent that this matter shines brightly in X-rays, the team reports, which they used to establish that 4U 1630-472 is rotating and calculate its speed.

So fast it’s glowing

If a black hole is rotating rapidly enough, it should — according to the general theory of relativity — distort space-time around it differently than a non-rotating black hole, the team explains. Such distortions would leave a measurable trace on the radiation emitted by the matter it’s absorbing.

Therefore, researchers can look at a black hole’s emission spectra to determine the rate it’s spinning at.

“Detecting signatures that allow us to measure spin is extremely difficult,” says lead author Dr. Mayukh Pahari from the University of Southampton. “The signature is embedded in the spectral information which is very specific to the rate at which matter falls into the black hole.”

“The spectra, however, are often very complex mostly due to the radiation from the environment around the black hole.”

Dr. Pahari says the team was “lucky” to obtain a spectral reading directly from the matter falling into the black hole, sans the background noise. Armed with that data, it was “simple enough to measure the distortion caused by the rotating black hole,” he says.

The findings from this study are significant, as this is one of only a handful of times we’ve managed to accurately measure a black hole’s spin rate. Only five other black holes have shown high spin rates, the team adds. Astronomical black holes can be fully characterized by mass and spin rate. Therefore, measuring these two properties is key to understanding some extreme aspects of the universe and the fundamental physics related to them.

The paper “AstroSat and Chandra View of the High Soft State of 4U 1630–47 (4U 1630–472): Evidence of the Disk Wind and a Rapidly Spinning Black Hole” has been published in The Astrophysical Journal.

Supermassive Black Hole.

Supermassive black holes like to wear gas donuts — and we found out why

Supermassive black holes don’t really form dust ‘donuts’ — the structures surrounding these bodies are more akin to galactic matter fountains, new research reveals.

Supermassive Black Hole.

Artist’s concept of a supermassive black hole. Also shown are the accretion disk (donut) and the outflowing jet of energetic particles.
Image credits NASA-JPL.

Computer simulations and new observations from the Atacama Large Millimeter/submillimeter Array (ALMA) suggest that the gas accretion rings around supermassive black holes (SBH) aren’t ring-shaped at all. Instead, gas being expelled from the SBM interacts with infalling matter to create a complex circulation pattern — one which the authors liken to a fountain.

Jets of matter

Most galaxies revolve around a SBH. These objects can be millions, even billions of times as heavy as the Sun, and they knit together galaxies through sheer gravitational power. Some of these SBHs are actively consuming new material. So far, common wisdom held that instead of falling directly in, matter builds around an active black hole in a donut or ring-shaped structure.

It wasn’t far from the truth but, new research reveals, it wasn’t spot-on either. A study led by Takuma Izumi, a researcher at the National Astronomical Observatory of Japan (NAOJ), reports that this ‘donut’ is not actually a rigid structure, rather a complex collection of highly dynamic gaseous components.

The researchers used the ALMA telescope to observe the Circinus Galaxy and the SBH at its center — which is roughly 14 million light-years away from Earth. They then compared their observations to computer models of gas falling toward a black hole. These simulations were run using the Cray XC30 ATERUI supercomputer operated by NAOJ.

All in all, the team found that there’s a surprising level of interplay between the gases in this structure. Cold molecular gas first falls towards the black hole to form a disk near the plane of rotation. Being so close to a black hole heats up the gas until its atoms break apart into protons and electrons. Not all of these products go on to be swallowed by the black hole. Some are instead expelled above and below the disk but are then snagged by the SBH’s immense gravitational presence, falling back onto the disk.

SBH interaction.

Rough schematic of the process’ dynamics. Pc stands for parsec, equal to about 3.26 light-years (30 trillion km or 19 trillion miles).

These three components circulate continuously, the team explains. Their interaction creates three-dimensional flows of highly turbulent matter around the black hole.

“Previous theoretical models set a priori assumptions of rigid donuts,” explains co-author Keiichi Wada, a theoretician at Kagoshima University in Japan who lead the simulation study.

“Rather than starting from assumptions, our simulation started from the physical equations and showed for the first time that the gas circulation naturally forms a donut. Our simulation can also explain various observational features of the system.”

The team says their paper finally explains how donut-shaped structures form around active black holes and, according to Izumi, will “rewrite the astronomy textbooks.”

The paper ” Circumnuclear Multiphase Gas in the Circinus Galaxy. II. The Molecular and Atomic Obscuring Structures Revealed with ALMA” has been published in The Astrophysical Journal.

Black lung disease makes resurgence among US coal miners

“This is history going in the wrong direction,” researchers say.

Progressive massive fibrosis (PMF), the most debilitating and deadly form of black lung disease, is increasing among US coal miners despite the implementation of dust controls decades ago, according to new research. Image credits: ATS.

Working in a coal mine is not an easy feat. The gruesome physical work, the closed spaces, and the lack of light makes for a hellish, unwelcoming environment. To top it all off, these miners often develop lung problems. The miners’ lung diseases weren’t well understood until the 1950s. Among these diseases, one was particularly prevalent: black lung disease.

Coal workers’ pneumoconiosis (CWP), commonly called black lung disease, is caused by long exposure to coal dust and can have devastating consequences. In 2013, CWP resulted in 25,000 deaths, but this was down from 29,000 deaths in 1990. Although it’s still a very big number, the trend seemed to be going down; seemed being the key word here.

In a new study, researchers analyzed U.S. Department of Labor data collected from former coal miners applying for benefits under the Federal Black Lung Program since the program began in 1970 until 2016. The start of the program coincides with the adoption of modern dust control measures in mines, which is when you’d expect the CWP numbers to go down.

That is, indeed, what was observed — until a point. In total, 4,679 coal miners were determined to have PMF, which was not unexpected. However, the numbers started to go up again in recent years. Black lung disease seems to be making a surprising resurgence.

“We were, however, surprised by the magnitude of the problem and are astounded by the fact that this disease appears to be resurging despite modern dust control regulations,” Dr. Almberg said. “This is history going in the wrong direction.”

Dr. Almberg said that it’s not exactly clear why this is happening, but there are a few possible explanations. Firstly, the affected miners appear to be working in smaller operations, which are less likely to invest in dust reduction systems.  Secondly, modern mines also produce higher levels of crystalline silica, which is even more damaging to the lungs than coal dust. Lastly, miners appear to be working longer hours and more days per week, which increases exposure and gives their bodies less time to recover. The last part adds an extra layer of serious concern regarding the miners’ health.

“In general, the higher concentration of dust, the more days worked per week, and the more years worked, the greater the risk,” she said. “It’s a classic dose-response relationship.”

In recent years, however, the US coal industry has embarked on a steady decline, being compensated and slowly replaced by renewable energy.  Despite President Trump’s campaign pledges, the coal industry is not making a resurgence — it’s simply not profitable, and too dirty. Black lung disease, however, appears to be on the rise.

The findings will be presented at the ATS 2018 International Conference.

Scientists may have seen a black hole being born for the first time ever

Scientists think they spotted the first-ever glimpse of how black holes form from a former supernova 20 million light-years away.

The Gargantua black hole from Interstellar.
Image credits Double Negative

When massive stars grow old and start running short on fuel, they explode in a dazzling display of light — a supernova. Huge quantities of matter and radiation are shot out at incredible speeds, squishing the core into something so dense that not even light can escape its gravitational pull — a leftover we call a black hole.

That’s what we think happens, anyway — we’ve never actually seen it per se. But now, an Ohio State University of Columbus team led by Christopher Kochanek might have witnessed it. They were combing through data from the Hubble Space Telescope when they observed something strange with the red supergiant star N6946-BH1.

Crunch time

The star was discovered in 2004 and was estimated to be roughly 25 times as massive as the Sun. But when Kochanek and his team looked at snaps taken in 2009, they found that the star flared a to a few million times the brightness of our star for a few months then slowly started to fade away. On the photos Hubble took in the visible spectrum, the star had all but disappeared — the only trace left of its presence is a faint infrared signature.

What happened to N6946-BH1 fits in nicely with what our theories predict should happen when a star its size collapses into a black hole. When it runs out of fuel, the star releases an immense number of neutrinos, so many that it starts losing mass. This in turn weakens its gravitational field, so it starts losing its grip on the cloud of super-heated hydrogen ions enveloping it. As the gas floats away it cools off enough for electrons to re-attach to the hydrogen nuclei.

Now, a star is basically an explosion so massive it keeps itself together under its own weight. Gravity on one hand tries to crunch everything into a point, while the pressure generated by fusion inside the star pushes it outward. While these two are in balance, the star burns away merrily. But once it starts running out of fuel, gravity wins and draws everything together. Matter sinks in the core making it so dense that it collapses in on itself, forming a black hole.

Ironically, it’s gravity that makes stars explode into supernovas — the outer layers are drawn towards the core at such speeds that they bounce off, compacting the core even further. N6946-BH1 didn’t make it to a supernova, but its core did collapse into a black hole. The team theorizes that the flaring we’ve seen is caused by super-heated gas forming an accretion disk around the singularity.

“The event is consistent with the ejection of the envelope of a red supergiant in a failed supernova and the late-time emission could be powered by fallback accretion onto a newly-formed black hole,” the authors write.

We’re still looking for answers

There are two other ways to explain a vanishing star, but they don’t really stand up to scrutiny. N6946-BH1 could have merged with another star — but it should have burned even brighter than before and for longer than a few months — or it could be enveloped in a dust cloud — but it wouldn’t have hidden it for so long.

“It’s an exciting result and long anticipated,” says Stan Woosley at Lick Observatory in California.

“This may be the first direct clue to how the collapse of a star can lead to the formation of a black hole,” says Avi Loeb at Harvard University.

Thankfully, confirming whether or not we’re looking at a black hole isn’t very difficult. The gasses that make up the accretion disk should emit a specific spectrum of X-rays as its being pulled into the black hole, which we can pick up. Kochanek says his group will be getting new data from Chandra X-Ray Observatory sometime in the next two months.

So is this a black hole? Even if they don’t pick up on any X-rays, the team says it doesn’t rule out such an object and that they will continue to look through Hubble – the longer the star is not there, the more likely that it’s a black hole.

“I’m not quite at ‘I’d bet my life on it’ yet,” Kochanek says, “but I’m willing to go for your life.”

The full paper titled “The search for failed supernovae with the Large Binocular Telescope: confirmation of a disappearing star” is still awaiting peer review, and has been published online on arXiv.

A sample of the new material. Image credit: Surrey Nanosystems

Blackest material resembles a black hole. It’s so black you can’t even see it

A sample of the new material. Image credit: Surrey Nanosystems

A sample of the new material. Image credit: Surrey Nanosystems

You might have thought black is too solemn or boring, but you may just change your mind. Through careful material science manipulation, involving thousands of tightly packed carbon nanotubes, British company Surrey NanoSystems made a super black coating that absorbs almost 99.96%  of visual light – a world record. Practically only a tiny fraction of the visual spectrum is reflected, so the only thing our eyes can discern is a bizarre abyss, akin to a black hole.

Dubbed Vantablack, the coating is made up of carbon nanotubes – rolled-up sheets of carbon 10,000 thinner than a strand of human hair – that are so tightly packed together that light can’t pass through. It’s only the ultra-short wavelength light that peers through, but that’s far from being enough to actually make the material look like … anything but void.

The nanotubes were grown on sheets of aluminium, but even if you fold and twist the Vantablack material in any direction any shapes, counters or depth become entirely lost because of the material’s light absorbing capabilities.

“You expect to see the hills and all you can see … it’s like black, like a hole, like there’s nothing there. It just looks so strange,” said Ben Jensen, the firm’s chief technical officer.

The material will be used to calibrate optical instruments like astronomical cameras, telescopes and infrared scanning systems to get better readings. Also, because it’s SO black, the material conducts heat seven and a half times more effectively (remember Planck’s law) than copper and has 10 times the tensile strength of steel (an inherent property of carbon nanotubes).

“It reduces stray-light, improving the ability of sensitive telescopes to see the faintest stars, and allows the use of smaller, lighter sources in space-borne black body calibration systems. Its ultra-low reflectance improves the sensitivity of terrestrial, space and air-borne instrumentation”, said Jensen in a release.
“Many people think black is the absence of light. I totally disagree with that. Unless you are looking at a black hole, nobody has actually seen something which has no light,” professor of colour science and technology Stephen Westland from Leeds University in the UK told The Independent. “These new materials, they are pretty much as black as we can get, almost as close to a black hole as we could imagine.”

The Vantablack coating was described in a paper published in the journal Optics Express.