From SLAC National Accelerator Lab via Science Alert: “Neptune Rains Diamonds, And Now We Might Finally Know How”

From SLAC National Accelerator Lab

via

Science Alert

29 JUNE 2020
MICHELLE STARR

Greg Stewart/SLAC National Accelerator Laboratory

Deep within the hearts of Neptune and Uranus, it could be raining diamonds. Now, scientists have produced new experimental evidence showing how this could be possible.

The hypothesis goes that the intense heat and pressure thousands of kilometres below the surface of these ice giants should split apart hydrocarbon compounds, with the carbon compressing into diamond and sinking even deeper towards the planetary cores.

The new experiment used the SLAC National Accelerator Laboratory’s Linac Coherent Light Source (LCLS) [below] X-ray laser for the most precise measurements yet of how this ‘diamond rain’ process should occur – and found that carbon transitions directly into crystalline diamond.

“This research provides data on a phenomenon that is very difficult to model computationally: the ‘miscibility’ of two elements, or how they combine when mixed,” explained plasma physicist Mike Dunne, director of the LCLS, and not listed as an author on the paper.

“Here they see how two elements separate, like getting mayonnaise to separate back into oil and vinegar.”

Neptune and Uranus are the most poorly understood planets in the Solar System. They are prohibitively far – only a single space probe, Voyager 2, has even been close to them, and only for a flyby, not a dedicated long-term mission.

NASA/Voyager 2

But ice giants are extremely common in the broader Milky Way – according to NASA, Neptune-like exoplanets are 10 times more prevalent than Jupiter-like exoplanets.

Understanding our Solar System’s ice giants, therefore, is vital to understanding planets throughout the galaxy. And to understand them better, we need to know what happens underneath their serene blue exteriors.

We know that the atmospheres of Neptune and Uranus are primarily made up of hydrogen and helium, with a small amount of methane. Below these atmospheric layers, a superhot, superdense fluid of ‘icy’ materials such as water, methane, and ammonia wraps around the planet’s core.

And calculations [Science] and experiments dating back decades have shown that, with sufficient pressure and temperature, methane can be broken down into diamonds – suggesting that diamonds can form within this hot, dense material.

A previous experiment at SLAC led by physicist Dominik Kraus at the Helmholtz-Zentrum Dresden-Rossendorf in Germany used X-ray diffraction to demonstrate it. Now Kraus and his team have taken their research a step further. The research has been published in Nature Astronomy.

The Matter in Extreme Conditions instrument at SLAC. Credit: SLAC National Accelerator Laboratory

“We now have a very promising new approach based on X-ray scattering,” Kraus said about their latest efforts. “Our experiments are delivering important model parameters where, before, we only had massive uncertainty. This will become ever more relevant the more exoplanets we discover.”

It’s challenging to replicate the interiors of giant planets here on Earth. You need some pretty intense equipment – that’s the LCLS. And you need a material that replicates the stuff inside that giant planet. For this, the team used the hydrocarbon polystyrene (C8H8) in place of methane (CH4).

The first step is to heat and pressurise the material to replicate the conditions inside Neptune at a depth of around 10,000 kilometres (6,214 miles): pulses of optical laser generate shockwaves in the polystyrene, which heats the material up to around 5,000 Kelvin (4,727 degrees Celsius, or 8,540 degrees Fahrenheit). It also creates intense pressure.

“We produce about 1.5 million bars, that is equivalent to the pressure exerted by the weight of some 250 African elephants on the surface of a thumbnail,” Kraus said [HZDR].

This is important, because there’s something really weird about Neptune. Its interior is way hotter than it should be; in fact, it gives off 2.6 times more energy than it absorbs from the Sun.

If diamonds – more dense than the material around them – are raining down into the planet’s interior, they could be releasing gravitational energy, which is converted into heat generated by friction between the diamonds and the material around them.

This experiment suggests we don’t have to find an alternative explanation… not yet, at any rate. And it also shows a method we could use to ‘probe’ the interiors of other planets in the Solar System.

“This technique will allow us to measure interesting processes that are otherwise difficult to recreate,” Kraus said.

“For example, we’ll be able to see how hydrogen and helium, elements found in the interior of gas giants like Jupiter and Saturn, mix and separate under these extreme conditions. It’s a new way to study the evolutionary history of planets and planetary systems, as well as supporting experiments towards potential future forms of energy from fusion.”

The new research has been published in Nature Communications.

See the full article here .

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SLAC National Accelerator Lab

SLAC/LCLS

SLAC/LCLS II projected view

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

SSRL and LCLS are DOE Office of Science user facilities.

From Science Alert: “An Unexpected Radiation Spike Has Been Detected Over Europe”

From Science Alert

29 JUNE 2020
PETER DOCKRILL

A mysterious increase in radiation levels over northern Europe was detected this month by authorities from several countries, although no nation has yet come forward to claim responsibility for the anomaly.

The subtle radiation spike – at levels that are considered harmless to humans, but significant enough to be picked up by radiation monitoring stations – began to make headlines last week, with European authorities announcing new readings of human-made radionuclide particles in the atmosphere.

“Very low levels of the radioactive substances cesium-134, cesium-137, cobalt-60 and ruthenium-103 were measured,” the Swedish Radiation Safety Authority tweeted on Tuesday.

“The levels measured are so low that they pose no danger to people or the environment.”

Similar observations were also made by radiation protection authorities in Norway and Finland.

Later in the week, Lassina Zerbo, the Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organisation, tweeted a map outlining the possible source region of the anomaly, most of which was territory inside Russia, but also parts of Finland, Sweden, Denmark, and Norway.

12:56 – 26 Jun 2020 · Vienna, Austria, Lassina Zerbo

“These isotopes are most likely from a civil source,” Zerbo tweeted, suggesting a source related to nuclear power production, not nuclear weapons.

“We are able to indicate the likely region of the source, but it’s outside the CTBTO’s [Comprehensive Nuclear-Test-Ban Treaty Organization] mandate to identify the exact origin.”

_____________________________________________
From RIVM

In the first half of June 2020, small amounts of artificial (man-made) radioactive substances have been detected at several measuring stations in Northern Europe. The Swedish, Norwegian and Finnish radiation protection authorities have reported this on their websites. RIVM National Institute for Public Health and the Environment has analysed the available data to determine a possible cause and source location.

Iodine-131 was detected in Norway, while cesium-134, cesium-137, cobalt-60 and ruthenium-103 were detected in Sweden and Finland. The amount of radioactivity was very low and there was no impact on the environment or human health. No artificial radioactive substances have been found in The Netherlands. RIVM National Institute for Public Health and the Environment continuously monitors the presence of radioactivity in The Netherlands. Detecting very low levels of radioactivity (such as in this case) is only possible with advanced equipment. Such equipment is available at RIVM.

Possible cause and source

The detected radioactive substances are artificial. The combination of radionuclides may be explained by an anomaly in the fuel elements of a nuclear power plant. RIVM has performed calculations to find out the source of the radionuclides. The calculations indicate that the nuclides come from the direction of western Russia. Determining a more specific source location is not possible with the limited data available.

Note: Some recent media reports claimed, possibly based on a mistranslation of our original report (in Dutch ), that the radionuclides originated from western Russia. The claim RIVM makes is that the radionuclides travelled from the direction of western Russia to Scandinavia, but that no specific country of origin can be pointed out at this moment.

A similar situation occurred in 2017: radioactive ruthenium-106 was found in the air in several European countries. Because many more measurements were available then, RIVM was able to locate the source more accurately. The calculated source was in excellent agreement with an existing nuclear facility that was pointed out as the most probable source in multiple international investigations.
_____________________________________________

On Friday, the Dutch National Institute for Public Health and the Environment (RIVM) announced that, based on an analysis of the available data, the “combination of radionuclides may be explained by an anomaly in the fuel elements of a nuclear power plant”.

On the available evidence, the organisation suggested that the radioactive particles detected had come from the direction of western Russia, but clarified that this did not mean they were definitively linked with Russian power plants.

“Some recent media reports claimed, possibly based on a mistranslation of our original report (in Dutch), that the radionuclides originated from western Russia,” RIVM said in a statement.

“The claim RIVM makes is that the radionuclides travelled from the direction of western Russia to Scandinavia, but that no specific country of origin can be pointed out at this moment.”

In response to online speculation that Russia was behind the radiation spike, a spokesperson for Rosenergoatom, part of Rosatom state nuclear energy corporation, said the nation’s two nuclear power plants in the region were operating normally, with normal radiation levels being reported.

“Both stations are working in normal regime. There have been no complaints about the equipment’s work,” Rosenergoatom told Russian news agency TASS.

“Aggregated emissions of all specified isotopes in the above-mentioned period did not exceed the reference numbers. No incidents related to release of radionuclide outside containment structures have been reported.”

As it stands, it’s hard to say whether additional evidence will be able to confirm where this slight radiation surge originated, but the incident recalls a similar situation that took place in 2017, in which another radioactive cloud was detected over Europe.

During that episode – which was also detected at levels harmless to people – many suggested Russian power plants were responsible – a hypothesis that was later supported by scientific findings, although disputed by Rosatom.

See the full article here .

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From U Leicester via Science Alert: “Yellowstone Discovery Suggests The Risk of Super-Eruption Is Actually Decreasing”

From U Leicester

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Science Alert

6 JUNE 2020
DAVID NIELD

(National Park Service, USA)

Two newly discovered super-eruptions have been found hidden in the geological history of Yellowstone National Park – including one that ranks in the fifth biggest volcanic eruption of all time.

The good news is that these additions suggest activity at the magma-fuelled hotspot is actually on the wane, according to a new study.

That’s despite the recent eruption clusters detected around the Yellowstone Caldera volcanic hollow.

“At Yellowstone and some other volcanoes, some scientists theorize that the earth’s crust fractures and cracks in a concentric or ring-fracture pattern. At some point these cracks reach the magma “reservoir,” release the pressure, and the volcano explodes. The huge amount of material released causes the volcano to collapse into a huge crater—a caldera.” From http://www.nps.gov

The two new-found events have been named the McMullen Creek eruption (occurring about 8.99 million years ago) and the Grey’s Landing eruption (occurring about 8.72 million years ago), and they significantly adjust Yellowstone’s long-term volcanic timeline – and appear to show that huge eruptions are now occurring way less frequently than they once did.

Scientists were able to use a combination of chemical, magnetic, and radio-isotopic analysis to link volcanic deposits across tens of thousands of square kilometres (or several thousand square miles), joining together geological records that were previously treated as separate.

In other words, what had been seen as many smaller eruptions were in fact two giant ones.

“We discovered that deposits previously believed to belong to multiple, smaller eruptions were in fact colossal sheets of volcanic material from two previously unknown super-eruptions at about 9.0 and 8.7 million years ago,” says volcanologist Thomas Knott, from the University of Leicester in the UK [GSA].

“The younger of the two, the Grey’s Landing super-eruption, is now the largest recorded event of the entire Snake-River–Yellowstone volcanic province. It is one of the top five eruptions of all time.”

According to the study data and estimates, Grey’s Landing would have covered an area the size of New Jersey in ultra-hot volcanic glass – somewhere in the region of 23,000 square kilometres (or 8,880 square miles). It would have vapourised anything in its path, and spewed out a cloud of fine ash across the globe.

With both newly identified events occurring during the Miocene period (23–5.3 million years ago), it raises the number of Yellowstone super-eruptions during that time to six – or one every 500,000 years, on average.

Compare that to the two super-eruptions that are thought to have happened across the same region during the last three million years, an average of one every 1.5 million years or so, and it seems as though the activity is getting more sporadic.

“It therefore seems that the Yellowstone hotspot has experienced a three-fold decrease in its capacity to produce super-eruption events,” says Knott. “This is a very significant decline.”

Super-eruptions, which are described as “landscape-changing extreme events that perturb global climate and devastate environments” in the published paper, need to register a magnitude 8 on the official Volcanic Explosivity Index (VEI).

But just because they appear to be getting less common doesn’t necessarily mean we can lower our guard when it comes to anticipating the next cataclysmic event – even if it might not happen for hundreds of thousand years.

Keeping the Yellowstone geysers, mudpots, and fumaroles under close observation remains a “must” according to the scientists. Even if activity in the Yellowstone region is on the wane, that doesn’t mean that it’s dormant yet. Meanwhile, the same techniques used here could be applied elsewhere in the future.

“We hope the methods and findings we present in our paper will enable the discovery of more new super-eruption records around the globe,” says Knott.

The research has been published in Geology.

See the full article here .

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The University of Leicester (Listeni/ˈlɛstə/ LES-tər) is a public research university based in Leicester, England. The main campus is south of the city centre, adjacent to Victoria Park.

The university has established itself as a leading research-led university and has been named University of the Year of 2008 by the Times Higher Education.[5] The University of Leicester is also the only university ever to have won a Times Higher Education award in seven consecutive years. In 2016, the university ranked 24th in the The Complete University Guide and 32nd in the The Guardian. Recent REF 2014, the University of Leicester ranked 49th among 126 universities.[6] The 2012 QS World University Rankings also placed Leicester eighth in the UK for research citations.[7]

The university is most famous for the invention of genetic fingerprinting and for the discovery of the remains of King Richard III.

From National Autonomous University of Mexico via Science Alert: “Earth’s Sixth Mass Extinction Isn’t Just Happening, It’s Accelerating”

From National Autonomous University of Mexico

via

Science Alert

2 JUNE 2020
PETER DOCKRILL

The critically endangered black rhinoceros. (James Warwick/Getty Images)

There are not as many of us as there used to be. Hundreds of unique, precious species of animal life vanished forever last century.

This is what a mass extinction looks like, scientists warn, but that’s not even the worst part.

The mass extinction phenomenon currently underway on Earth is actually accelerating, researchers now say, with the vast toll of vertebrate extinctions seen in the 20th century set to be repeated – but this time, it may take just decades for hundreds more species to disappear for all time.

As each domino falls, the knock-on effects for adjacent species become ever more risky, with destabilised ecosystems and weakened food webs making survival for any species – including humans – less assured.

“What we do to deal with the current extinction crisis in the next two decades will define the fate of millions of species,” explains ecologist Gerardo Ceballos from the National Autonomous University of Mexico.

Five years ago, Ceballos led a study that used conservative estimates to reveal the massive discrepancy between ordinary (‘background’) rates of species extinction and the spate of die-offs we see today.

It found the average rate of vertebrate species extinctions (two mammal extinctions per 10,000 species every 100 years) was drastically less than today’s extinction toll, which is up to 100 times higher over the last century.

This, the team said, effectively showed that a mass extinction phenomenon is unfolding right now, due to “incontrovertible” evidence that recent extinction levels, themselves unprecedented in human history, are highly unusual in Earth’s history.

“We can confidently conclude that modern extinction rates are exceptionally high, that they are increasing, and that they suggest a mass extinction under way – the sixth of its kind in Earth’s 4.5 billion years of history,” the team wrote in their 2015 paper [Science Advances].

Now, Ceballos and his collaborators are back with another study [PNAS], and their new insights are not any more optimistic.

This time around, the researchers say future rates of extinction have probably been underestimated up to this point, with the rapid rates of vertebrate extinction we’re already witnessing expected to increase sharply in the future.

In the study, the team used data from the IUCN Red List of Threatened Species and Birdlife International to examine populations of vertebrate animals considered to be on the brink of extinction, having lost most of their geographic range, and now consisting of fewer than 1,000 living individuals worldwide.

According to the researchers, 1.7 percent of assessed terrestrial vertebrate species – 515 species in total – fit this description, with about half having fewer than 250 survivors.

An additional 388 species fare a little better – with populations ranging between 1,000 and 5,000 individuals – but the team says 84 percent of these animals live in the same regions as the 515 species on the brink of extinction, which suggests they are likely to be exposed to the same geographical threats, in terms of things like destabilised ecosystems due to disrupted food chains, deforestation, pollution, or other myriad other human pressures.

“Close ecological interactions of species on the brink tend to move other species toward annihilation when they disappear – extinction breeds extinctions,” the researchers write.

These ‘extinction cascades’, triggered by the loss of certain keystone species within ecosystems, are a well-known phenomenon in ecology, and because so many kinds of animals are on the verge of being on the brink of extinction, the mass extinction could be happening sooner than we had anticipated, because when animal populations get pressured to such extreme extents, they generally don’t last long.

“Around 94 percent of the populations of 77 mammal and bird species on the brink have been lost in the last century,” the team writes.

“Assuming all species on the brink have similar trends, more than 237,000 populations of those species have vanished since 1900.”

If the 515 species on the brink only last for another few decades, which the researchers speculatively estimate, then, combined with the 543 vertebrate species known to have gone extinct since 1900, extinction rates would be 117 times higher than the background rate – higher than the researchers’ own estimates five years ago, suggesting we’ve previously underestimated how fast this process is happening.

It’s not too late to slow this, the researchers say, if we take action to ease human pressures on the biosphere. This could be by implementing broad bans on the trade of wild species, slowing deforestation, and recognising all animal populations of less than 5,000 as critically endangered.

Whatever we do, we have to realise that this isn’t just the fate of other animals we’re talking about here.

“When humanity exterminates populations and species of other creatures, it is sawing off the limb on which it is sitting, destroying working parts of our own life-support system,” says one of the researchers, biologist Paul Ehrlich from Stanford University.

“The conservation of endangered species should be elevated to a national and global emergency for governments and institutions, equal to climate disruption to which it is linked.”

On that note, other scientists agree it’s possible to mitigate this huge problem – which the team says is probably the most pressing environmental issue facing living things – but only if we really work to prioritise a fix, rather than look the other way.

“The tragedy of all of this is that we have the knowledge to save species from extinction, and doing that is cheap in a global context,” says ecologist Chris Johnson from the University of Tasmania in Australia, who wasn’t involved in the study.

“But this task is just not given enough priority by society and governments.”

See the full article here .

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The National Autonomous University of Mexico (Spanish: Universidad Nacional Autónoma de México, lit. ‘Autonomous National University of Mexico’, UNAM) is a public research university in Mexico. It ranks highly in world rankings based on the university’s extensive research and innovation. It is the largest university in Latin America and has one of the biggest campuses in the world. UNAM’s main campus in Mexico City, known as Ciudad Universitaria (University City), is a UNESCO World Heritage site that was designed by some of Mexico’s best-known architects of the 20th century. Murals in the main campus were painted by some of the most recognized artists in Mexican history, such as Diego Rivera and David Alfaro Siqueiros. In 2016, it had an acceptance rate of only 8%. UNAM generates a number of strong research publications and patents in diverse areas, such as robotics, computer science, mathematics, physics, human-computer interaction, history, philosophy, among others. All Mexican Nobel laureates are either alumni or faculty of UNAM.

UNAM was founded, in its modern form, on 22 September 1910 by Justo Sierra as a liberal alternative to its predecessor, the Royal and Pontifical University of Mexico, the first to be founded in North America. UNAM obtained its autonomy from the government in 1929. This has given the university the freedom to define its own curriculum and manage its own budget without government interference. This has had a profound effect on academic life at the university, which some claim boosts academic freedom and independence.

From Science Alert: “Physicists Create a Group of 15 Trillion Entangled Atoms, Setting a Major New Record”

From Science Alert

23 MAY 2020
DAVID NIELD

The glass cell used for the experiment. (ICFO)

Quantum physicists have set a new record for collecting a persistent group of entangled atoms together, getting 15 trillion atoms to co-exist in a “hot and messy” cloud of gas.

Quantum entanglement is the phenomenon at the heart of quantum physics, where two particles can mysteriously influence each other, no matter what the distance is between them – so measuring one of them instantly gives us the measurement of the other.

While scientists don’t yet fully understand why this occurs, it does indeed happen; but demonstrating quantum entanglement remains a delicate and challenging process.

Entangled states need some very specific conditions to exist and survive, with most experiments in this area of research being conducted at temperatures approaching absolute zero.

Artistic illustration of the atom cloud. (ICFO)

That’s why this new study is such an achievement. The scientists were able to create a hot, chaotic gas of atoms heated to about 450 Kelvin (177° C or 350° F), packed full with around 15 trillion entangled atoms – around 100 times more than have ever been observed together before.

These atoms weren’t isolated either: measurements taken by lasers showed them colliding into each other, and there were sometimes thousands of other atoms between entangled pairs. The experiment also showed the state of entanglement may be stronger than previously realised.

“If we stop the measurement, the entanglement remains for about 1 millisecond, which means that 1,000 times per second a new batch of 15 trillion atoms is being entangled,” says quantum physicist Jia Kong from the Institute of Photonic Sciences in Spain (ICFO).

“You must think that 1 ms is a very long time for the atoms, long enough for about 50 random collisions to occur. This clearly shows that the entanglement is not destroyed by these random events. This is maybe the most surprising result of the work.”

Whereas most quantum entanglement experiments use ultra-low temperatures, to keep interference like these collisions down to a minimum, this study – using rubidium metal and nitrogen gas – shows that entanglement can survive much hotter temperatures.

If we’re going to be able to use this phenomenon in next-generation communication systems and quantum computers, we need to get it working in warmer, noisier environments, and that’s something this new research points the way to.

One of the ways these findings could be useful in the future is in magnetoencephalography or magnetic brain imaging, a process that uses similar hot, high-density atomic gases to detect magnetic fields created by brain activity. Entanglement could potentially make the technique more sensitive.

For now, though, scientists have learned more about the rules of quantum entanglement, and just what it can and can’t withstand.

“This result is surprising, a real departure from what everyone expects of entanglement,” says ICFO quantum physicist Morgan Mitchell.

“We hope that this kind of giant entangled state will lead to better sensor performance in applications ranging from brain imaging, to self-driving cars, to searches for dark matter.”

The research has been published in Nature Communications.

See the full article here .

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From ARC Centres of Excellence via Science Alert: “Astronomers Find a Record-Breaking Star That’s Nearly as Old as The Universe”

From ARC Centres of Excellence

via

Science Alert

16 MAY 2020
MICHELLE STARR

Artist’s impression of the first stars. (Wise, Abel, Kaehler (KIPAC/SLAC))

Another ancient star has been found lurking in the Milky Way. Around 35,000 light-years away, a red giant star named SMSS J160540.18–144323.1 was found to have the lowest iron levels of any star yet analysed in the galaxy.

This means that it’s one of the oldest stars in the Universe, probably belonging to the second generation of stars after the Universe burst into existence 13.8 billion years ago.

“This incredibly anaemic star, which likely formed just a few hundred million years after the Big Bang, has iron levels 1.5 million times lower than that of the Sun,” explained astronomer Thomas Nordlander of the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions and the Australian National University.

“That’s like one drop of water in an Olympic swimming pool.”

And that’s how we can tell how old the star is, because the very early Universe had no metals at all. The first stars were made up primarily of hydrogen and helium, and were thought to be very massive, very hot, and very short-lived. These stars are called Population III, and we’ve never seen them.

Stars are ‘powered’ by nuclear fusion, where the atomic nuclei of lighter elements are combined to create heavier ones. In smaller stars, that’s mainly the fusion of hydrogen into helium. But in larger stars – such as the Population III stars are thought to have been – elements up to and including silicon and iron can be forged.

When such stars end their lives in spectacular supernova explosions, they spew those elements out into the Universe. As new stars form, the elements get caught up in them – and thus, how much metal a star contains is a reliable indicator of when it formed.

For example, we know that the Sun is several – perhaps 100 – generations from the Big Bang, based on our star’s metallicity.

But we’ve found other stars in the Milky Way that have a low metallicity, indicating an early Universe origin. One such object is 2MASS J18082002–5104378 B, the previous record-holder for the lowest iron content of [Fe/H] = −4.07 ± 0.07 – around 11,750 times less metallic than the Sun.

But SMSS J160540.18–144323.1 is at [Fe/H] = −6.2 ± 0.2. As Nordlander said, that’s around 1.5 million times less metallic.

It’s unlikely any Population III stars survived long enough for us to study them. But through the stars that came after, their stories can be unravelled.

The researchers believe that the star that gave SMSS J160540.18–144323.1 its iron was relatively low mass for the early Universe, only around 10 times the mass of the Sun. This is massive enough to produce a neutron star; and, after a comparatively weak supernova, the team believes this is what it did.

A supernova explosion can trigger a rapid neutron-capture process, or r-process. This is a series of nuclear reactions in which atomic nuclei collide with neutrons to synthesise elements heavier than iron.

There was no significant evidence of these elements in the star, which could mean that these elements were captured back by the newly dead neutron star. But enough iron escaped that it was incorporated into the formation of SMSS J160540.18–144323.1.

It was likely one of the very first members of that second generation of stars.

And it’s dying. It’s a red giant, which means the star is at the very end of its lifespan, using up the last of its hydrogen before it switches to helium fusion.

The team believes that studying it more closely could yield even more information about Population III stars. But imagine the stories it could tell if it could talk.

The research has been published in the Monthly Notices of the Royal Astronomical Society.

See the full article here .

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The objectives for the ARC Centres of Excellence are to to:

undertake highly innovative and potentially transformational research that aims to achieve international standing in the fields of research envisaged and leads to a significant advancement of capabilities and knowledge
link existing Australian research strengths and build critical mass with new capacity for interdisciplinary, collaborative approaches to address the most challenging and significant research problems
develope relationships and build new networks with major national and international centres and research programs to help strengthen research, achieve global competitiveness and gain recognition for Australian research
build Australia’s human capacity in a range of research areas by attracting and retaining, from within Australia and abroad, researchers of high international standing as well as the most promising research students
provide high-quality postgraduate and postdoctoral training environments for the next generation of researchers
offer Australian researchers opportunities to work on large-scale problems over long periods of time
establish Centres that have an impact on the wider community through interaction with higher education institutes, governments, industry and t

From Science Alert: “Astronomers Make Incredibly Rare Detection of Earth-Like Planet 25,000 Light-Years Away”

From Science Alert

12 MAY 2020
MICHELLE STARR

Artist’s impression of a super-Earth. (ESO/spaceengine.org)

There may be multitudes of Earth-like planets sprinkled throughout the Milky Way galaxy, but they are not so easy to find. To date, only around a third of the over 4,000 exoplanets found and confirmed are rocky – and most of those are within a few thousand light-years of Earth.

So the announcement of a new rocky exoplanet is always exciting – but this particular newly discovered rocky exoplanet is even more exciting yet.

It belongs to the much smaller subset of rocky exoplanets that orbit at an Earth-like distance from its star. And it’s a whopping 24,722.65 light-years away from us – which could make it the most distant Milky Way exoplanet discovered yet.

It’s so distant, it’s close to – and might even be in – the galactic bulge, the densely populated region in the centre of the galaxy.

Although we are getting better and better at finding them, exoplanets are tricky little beasts. They don’t give off any light of their own, and any starlight they might reflect would be a tiny, tiny signal lost in the noise of their host star.

Most of the exoplanets we know of have been detected using one of two methods. There’s the transit method, which detects planets based in the regular, minuscule dips in starlight when an exoplanet passes in front of it; and there’s the wobble method, which detects minuscule wobbling exerted on a star by the gravitational influence of an exoplanet.

But there’s a third method, based on the predictions of general relativity: gravitational microlensing. Imagine two stars, one behind the other, and an observer (us) at some distance again. Rays of light from the rear star (the source) are slightly bent by the gravity of the closer star (the lens) as they pass by. This distorts and magnifies that source light – hence, gravitational microlens.

Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

We know what this looks like with two stars – there are so many out there that gravitational microlenses are not uncommon. Thus, when an exoplanet is thrown into the mix, it creates a further disturbance in the light that reaches the observer; we can recognise that as the signature of a planet.

Astronomers can then analyse the light curve of the microlensing event to determine the parameters of the system.

“To have an idea of the rarity of the detection, the time it took to observe the magnification due to the host star was approximately five days, while the planet was detected only during a small five-hour distortion,” explained astronomer Antonio Herrera Martin of the University of Canterbury in New Zealand.

“After confirming this was indeed caused by another ‘body’ different from the star, and not an instrumental error, we proceeded to obtain the characteristics of the star-planet system.”

The microlensing event – called OGLE-2018-BLG-0677 – was independently observed by two different experiments, the Optical Gravitational Lensing Experiment (OGLE) Early Warning System and the Korea Microlensing Telescope Network (KMTNet). These experiments generally detect around 3,000 microlensing events a year, most of which are just stars.

“Dr Herrera Martin first noticed that there was an unusual shape to the light output from this event, and undertook months of computational analysis that resulted in the conclusion that this event was due to a star with a low-mass planet,” said astronomer Michael Albrow of the University of Canterbury.

Both datasets contributed to the team’s analysis.

They determined that the exoplanet is a super-Earth, clocking in at around 3.96 times the mass of Earth. This makes it one of the lowest-mass planets ever discovered using gravitational microlensing.

The star it orbits is really small, just 0.12 times the mass of the Sun – so petite that the researchers couldn’t determine whether it was a low-mass star or a brown dwarf. And the orbital distance between the planet and the star is between 0.63 and 0.72 astronomical units – around the distance of Venus from the Sun. But because the star is so small, the planet moves around it pretty slowly – its year is around 617 days.

We won’t know if the exoplanet could be habitable any time soon. For one, we don’t know the nature of the star. The temperature and activity level of a host star play a big role in habitability, as we define it. And the star is so far away we aren’t even close to instruments sensitive enough to study its spectrum, to determine if it has an atmosphere.

But one of the biggest questions about life in the Universe is how often it has the opportunity to arise. We know it can arise on rocky exoplanets, since it did so here on Earth. So the more rocky exoplanets we find, the better we can understand that constraint.

What this research does demonstrate is the extraordinary power of gravitational microlensing as a tool to find those distant, low-mass exoplanets. And it’s damn awe-inspiring.

The research has been published in The Astronomical Journal.

See the full article here .

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From Science Alert: “An Ancient Meteorite Is The First Chemical Evidence of Volcanic Convection on Mars”

From Science Alert

11 MAY 2020
MICHELLE STARR

A composite Viking orbiter image of Olympus Mons on Mars, the tallest known volcano and mountain in the Solar System. NASA.

For many years, we thought Mars was dead. A dusty, dry, barren planet, where nothing moves but the howling wind. Recently, however, pieces of evidence have started to emerge, hinting that Mars is both volcanically and geologically active.

Well, the idea of a volcanically active Mars just got a little more real. A meteorite that formed deep within the belly of Mars has just provided the first solid chemical proof of magma convection within the Martian mantle, scientists say.

Crystals of olivine in the Tissint meteorite that fell to Earth in 2011 could only have formed in changing temperatures as it was rapidly swirled about in magma convection currents – showing that the planet was volcanically active when the crystals formed around 574 to 582 million years ago – and it could still be intermittently so today.

“There was no previous evidence of convection on Mars, but the question ‘Is Mars a still volcanically active planet?’ was previously investigated using different methods,” explained planetary geologist Nicola Mari of the University of Glasgow to ScienceAlert.

“However, this is the first study that proves activity in the Mars interior from a purely chemical point of view, on real Martian samples.”

Olivine, a magnesium iron silicate, isn’t rare. It crystallises from cooling magma, and it’s very common in Earth’s mantle; in fact, the olivine group dominates Earth’s mantle, usually as part of a rock mass. On Earth’s surface, it’s found in igneous rock.

It’s fairly common in meteorites. And olivine is also fairly common on Mars. In fact, the presence of olivine on the surface of Mars has previously been taken as evidence of the planet’s dryness, since the mineral weathers rapidly in the presence of water.

But when Mari and his team started studying the olivine crystals in the Tissint meteorite to try to understand the magma chamber where it formed, they noticed something strange. The crystals had irregularly spaced phosphorus-rich bands.

We know of this phenomenon on Earth – it’s a process called solute trapping. But it was a surprise to find it on Mars.

(Mari et al., Meteoritics & Planetary Science, 2020)

“This occurs when the rate of crystal growth exceeds the rate at which phosphorus can diffuse through the melt, thus the phosphorus is obliged to enter the crystal structure instead of ‘swimming’ in the liquid magma,” Mari said.

“In the magma chamber that generated the lava that I studied, the convection was so vigorous that the olivines were moved from the bottom of the chamber (hotter) to the top (cooler) very rapidly – to be precise, this likely generated cooling rates of 15-30 degrees Celsius per hour for the olivines.”

The larger of the olivine crystals were also revealing. Traces of nickel and cobalt are in agreement with previous findings that they originated from deep under the Martian crust, a depth of 40 to 80 kilometres (25 to 50 miles).

This supplied the pressure at which they formed; along with the equilibration temperature of olivine, the team could now perform thermodynamic calculations to discover the temperature in the mantle at which the crystals formed.

They found that the Martian mantle probably had a temperature of around 1,560 degrees Celsius in the Martian Late Amazonian period when the olivine formed. This is very close to the ambient mantle temperature of Earth of 1,650 degrees Celsius during the Archean Eon, 4 to 2.5 billion years ago.

That doesn’t mean Mars is just like an early Earth. But it does mean that Mars could have retained quite a bit of heat under its mantle; it’s thought that, because it lacks the plate tectonics that help to dissipate heat on Earth, Mars may cool more slowly.

“I really think that Mars could be a still volcanically active world today, and these new results point toward this,” Mari told ScienceAlert.

“We may not see a volcanic eruption on Mars for the next 5 million years, but this doesn’t mean that the planet is inactive. It could just mean that the timing between eruptions between Mars and Earth is different, and instead of seeing one or more eruptions per day (as on Earth) we could see a Martian eruption every n-millions of years.”

We’ll need more research to confidently say this hypothesis checks out. But these results also mean that previous interpretations of the planet’s dryness based on surface olivine may need to be revisited. (Although let us be clear, Mars is still extremely dry.)

The ongoing NASA InSight mission that recently found evidence of Marsquakes, measures – among other things – the heat flux from the Martian crust. If Mars is still volcanically active, we may know more about it really soon.

NASA/Mars InSight Lander

The research has been published in Meteoritics & Planetary Science.

See the full article here .

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From Science Alert: “Strangely Flaring Dead Star Could Be The ‘Missing Link’ Between Magnetars And Pulsars”

From Science Alert

1 MAY 2020
MICHELLE STARR

Artist’s impression of a magnetar. (ESO/L. Calçada)

One of the rarest and most mysterious stars in the galaxy has just been spotted behaving really strangely. Swift J1818.0-1607 is a magnetar, and astronomers have just recorded it spitting out staccato radio pulses.

This makes it only the fifth magnetar ever detected emitting pulsed radio waves… but it’s also doing so in a manner unlike any of the other four. Swift J1818.0-1607 was behaving more like a radio pulsar than a radio magnetar.

A paper describing the event has been uploaded to pre-print server arXiv [ https://arxiv.org/abs/2004.11522 ], and is yet to be peer reviewed. The observations could help astronomers to connect the dots between these two classifications of dead stars.

“I think it is safe to call it a potential missing link,” astrophysicist Marcus Lower of Swinburne University of Technology told ScienceAlert.

“At this stage there’s still a lot we don’t know about this new magnetar, but there are clear similarities between it and the high-magnetic field pulsars.”

Magnetars are really peculiar little oddballs. They’re a subcategory of neutron stars, which themselves are the incredibly dense core remnants left behind after a massive star goes supernova.

What makes magnetars stand out is their insanely powerful magnetic fields. We’re not talking small potatoes here. These magnetic fields are around a quadrillion times more powerful than Earth’s, and a thousand times more powerful than a normal neutron star’s. And we still don’t fully understand how they got that way.

They’re also really rare. We’ve only detected around 24 of these extreme stars in our galaxy to date, and of those, just a handful have been observed emitting radio waves.

Pulsars, on the other hand, are much more common – astronomers have identified thousands. These are rapidly spinning neutron stars that beam jets of radio radiation from their poles; when those jets are oriented to flash past Earth, they pulse, like a rapid cosmic lighthouse, on timescales as short as milliseconds.

Because both pulsars and magnetars are a kind of neutron star, it’s expected that there would be some crossover between them, but there has been surprisingly little. Initially, this was thought to be because the magnetic field was too powerful to support pulsar-like radio emission.

More recently, however, the thinking has shifted. Astronomers believe that most magnetars are just facing the wrong way.

“The most likely reason is their radio beams simply don’t cross our line-of-sight,” Lower explained. “This isn’t too surprising, as their slow rotation periods and the high rate at which they’re slowing down over time causes them to have very narrow radio beams when compared to other pulsars.”

That brings us back to Swift J1818.0-1607. On 12 March 2020, it was detected undergoing a gamma-ray outburst by the Burst Alert Telescope attached to the Swift Observatory. Follow-up observations quickly followed, detecting pulsed X-ray emission.

NASA Neil Gehrels Swift Observatory

Two days later, radio emission was detected, and initial analysis found that Swift J1818.0-1607 is the fastest rotating pulsar found to date – and it is likely also the youngest, just 240 years or so.

Using the Parkes Observatory radio telescope in Australia, Lower and his team also took observations.

CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia, 414.80m above sea level

They recorded the star for three hours, and found it emitting pulsed radio waves, not apparently very different from the other radio pulsars. But then they took a closer look at the data.

“At a glance, the radio pulses emitted by Swift J1818.0-1607 look quite similar to those from the four other radio magnetars. They’re very narrow and sometimes composed of multiple millisecond-long bursts,” Lower said.

“However when we looked at how bright the pulses are at different radio frequencies, we realized there is a dramatic drop-off in brightness when going from low to high frequencies. While this is similar to many ordinary radio pulsars, it is very different to the pulses seen from other magnetars. They tend to have an almost constant brightness across the radio spectrum.”

In fact, the radio outburst bore a striking resemblance to one pulsar in particular. In 2016, a high magnetic field pulsar called PSR J1119-6127 underwent a radio outburst of its own, and the spectrum of that outburst looked very similar to the spectrum from Swift J1818.0-1607.

In addition, Lower explained, the two stars exhibited a similar radio brightening – a tantalizing hint that the mechanism behind the radio outbursts could be similar.

It could also suggest that at least some magnetars could evolve from pulsars. How this process would play out is unclear, but there are a number of scenarios. A rapid slowdown in the rotation rate could cause a neutron star to exhibit the rotational properties of a magnetar. Alternatively, a collapsing neutron star could have a magnetar-like magnetic field from the start, but it’s buried under fallback material from the supernova, and takes some time to reemerge.

More observations would be needed to confirm. Magnetars are incredibly difficult to detect in the first place, so expanding the catalog is a challenge, but now we know that Swift J1818.0-1607 behaves this way, the star could become a bridge over that knowledge gap if we can study it for longer, and with more sensitive instrumentation.

“That this magnetar’s radio emission doesn’t exactly match our expectations from observations of other radio magnetars is quite exciting, and goes to show how much more we have yet to learn about these extreme objects,” Lower told ScienceAlert.

“Its similarity to more mundane pulsars opens a whole host of questions about its possible origins, how magnetars evolve over time and the validity of our previous assumptions about magnetar radio emission.”

See the full article here .

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From Science Alert- “Exclusive: We Might Have First-Ever Detection of a Fast Radio Burst in Our Own Galaxy”

From Science Alert

1 MAY 2020
MICHELLE STARR

A Milky Way magnetar called SGR 1935+2154 may have just massively contributed to solving the mystery of powerful deep-space radio signals that have vexed astronomers for years.

ATel #13682: AGILE observations of the SGR 1935+2154 “burst forest”

On 28 April 2020, the dead star – sitting just 30,000 light-years away – was recorded by radio observatories around the world, seemingly flaring with a single, millisecond-long burst of incredibly bright radio waves that would have been detectable from another galaxy.

In addition, global and space X-ray observatories recorded a very bright X-ray counterpart.

Work on this event is very preliminary, with astronomers madly scrambling to analyse the swathes of data. But many seem in agreement that it could finally point to the source of fast radio bursts (FRBs).

“This sort of, in most people’s minds, settles the origin of FRBs as coming from magnetars,” astronomer Shrinivas Kulkarni of Caltech, and member of one of the teams, the STARE2 survey that also detected the radio signal, told ScienceAlert.

Fast radio bursts are one of the most fascinating mysteries in the cosmos. They are extremely powerful radio signals from deep space, galaxies millions of light-years away, some discharging more energy than 500 million Suns. Yet they last less than the blink of an eye – mere milliseconds in duration – and most of them don’t repeat, making them very hard to predict, trace, and therefore understand.

Potential explanations have ranged from supernovae to aliens (which, sorry, is extremely unlikely). But one possibility that has been picking up steam is that FRBs are produced by magnetars.

These are a particularly odd type of neutron star, the extremely dense core remnants left over after a massive star goes supernova. But magnetars have much more powerful magnetic fields than ordinary neutron stars – around 1,000 times stronger. How they got that way is something we don’t understand well, but it has an interesting effect on the star itself.

As gravitational force tries to keep the star together – an inward force – the magnetic field is so powerful, it distorts the star’s shape. This leads to an ongoing tension between the two forces, Kulkarni explained, which occasionally produces gargantuan starquakes and giant magnetar flares.

On 27 April 2020, SGR 1935+2154 was detected and observed by multiple instruments undergoing a spurt of activity, including the Swift Burst Alert Telescope, the AGILE satellite and the NICER ISS payload. It initially looked relatively normal, consistent with behaviour observed in other magnetars.

NASA Neil Gehrels Swift Observatory

Italian Space Agency AGILE Spacecraft

NASA/NICER on the ISS

But then, on April 28, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) – a telescope designed to scan the skies for transient events – made an unprecedented detection, a signal so powerful the system couldn’t quite quantify it. The detection was reported on The Astronomer’s Telegram.

CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia, the University of Toronto, McGill University, Yale and the National Research Council in British Columbia, at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, CA Altitude 545 m (1,788 ft)

But the STARE2 survey, a project started by Caltech graduate student Christopher Bochenek, is designed exactly for the detection of local FRBs. It consists of three dipole radio antennas located hundreds of kilometres apart, which firstly can rule out local signals produced by human activities, and can also allow for signal triangulation.

It received the signal loud and clear, with a fluence of over a million jansky milliseconds. Typically, we receive extragalactic FRBs at a few tens of jansky milliseconds. Once corrected for distance, the SGR 1935+2154 would be on the low end of FRB power – but it fits the profile, Kulkarni said.

“If the same signal came from a nearby galaxy, like one of the nearby typical FRB galaxies, it would look like an FRB to us,” he told ScienceAlert. “Something like this has never been seen before.”

But we also saw something else we’ve never seen in an extragalactic FRB, and that’s the X-ray counterpart. These are quite common in magnetar outbursts, of course. In fact, it is far more normal for magnetars to emit X-ray and gamma radiation than radio waves.

The X-ray counterpart to the SGR 1935+2154 burst was not particularly strong or unusual, said astrophysicist Sandro Mereghetti of the National Institute for Astrophysics in Italy, and research scientist with the ESA’s INTEGRAL satellite. But it could imply that there’s a lot more to FRBs than we can currently detect.

ESA/Integral

“This is a very intriguing result and supports the association between FRBs and magnetars,” Mereghetti told ScienceAlert.

“The FRB identified up to now are extragalactic. They have never been detected at X/gamma rays. An X-ray burst with luminosity like that of SGR1935 would be undetectable for an extragalactic source.”

But that radio signal was undeniable. And, according to Kulkarni, it’s absolutely possible for a magnetar to produce even larger outbursts. SGR 1935+2154’s burst did not require much energy, for a magnetar, and the star could easily handle a burst a thousand times stronger.

It’s certainly giddying stuff. But it’s important to bear in mind that this is early days yet. Astronomers are still conducting follow-up observations of the star using some of the most powerful tools we have.

And they have yet to analyse the spectrum of the burst, to determine if it bears any similarities to the spectra of extragalactic fast radio bursts. If it doesn’t, we may be back to square one.

Of course, even if SGR 1935+2154 does turn out to confirm a magnetar origin for fast radio bursts, that won’t mean it’s the only origin. Some of the signals behave very differently, repeating unpredictably. One source was recently found to be repeating on a 16-day cycle.

Whatever SGR 1935+2154 tells us, we are far from completely resolving the complicated enigma these incredible signals represent – but it’s an incredibly exciting step forward.

See the full article here .

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