Heavens

In their interiors, stars are structured in a layered, onion-like fashion. In those with solar-like temperatures, the core is followed by the radiation zone. There, the heat from within is led outwards by means of radiation. As the stellar plasma becomes cooler farther outside, heat transport is dominated by plasma flows: hot plasma from within rises to the surface, cools, and sinks down again. This process is called convection. At the same time, the star's rotation, which depends on stellar latitude, introduces shear movements. Together, both processes twist and twirl magnetic field lines and create a star's complex magnetic fields in a dynamo process that is not yet fully understood.

"Unfortunately, we cannot look directly into the Sun and other stars to see these processes in action, but have to resort to more indirect methods", says Dr. Jyri Lehtinen from the Max Planck Institute for Solar System Research (MPS) in Germany, first author of the new paper published today in Nature Astronomy. In their current study, the researchers compared different stars' activity levels on the one hand, and their rotational and convective properties on the other. The goal was to determine, which properties have a strong influence on activity. This can help to understand the specifics of the dynamo process within.

Several models of the stellar dynamo have been proposed in the past, but two main paradigms prevail. While one of them puts a greater emphasis on the rotation and assumes only subtle effects of convectional flows, the other depends crucially on turbulent convection. In this type of convection, the hot stellar plasma does not rise to the surface in large-scale, sedate motions. Rather, small-scale vigorous flows dominate.

In order to find evidence for one or the other of the two paradigms, Lehtinen and his colleagues for the first time took a look at 224 very different stars. Their sample contained both main sequence stars, which are so to say in the prime of their life, and older, more evolved giant stars. Typically, both convection and rotational properties of stars change as they age. Compared to main sequence stars, evolved stars exhibit a thicker convection zone often expanding over much of the star's diameter and sometimes superseding the radiation zone completely. This leads to longer turnover times for convective heat transport. At the same time, rotation usually slows down.

For their study, the researchers analyzed a data set obtained at Mount Wilson Observatory in California (USA), which over several years recorded the stars' emissions in wavelengths typical of calcium ions found in the stellar plasma. These emissions are not only correlated with the stars' activity level. Complex data processing also made it possible to infer the stars' rotation periods.

Like the Sun, stars are sometimes dappled with regions of extremely high magnetic field strength, so-called active regions, which are often associated with dark spots on the stars' visible surface. "As a star rotates, these regions come into view and pass out of it leading to a periodic rise and fall in emission brightness", Prof. Dr. Maarit Käpylä from Aalto University in Finland, who also heads the research group "Solar and Stellar Dynamos" at MPS, explains. However, since stellar emissions can also fluctuate due to other effects, identifying periodic variations - especially over long periods - is tricky.

"Some of the stars we studied show rotation periods of several hundreds of days, and surprisingly still a magnetic activity level similar to the other stars, and remarkably even magnetic cycles like the Sun", says Dr. Nigul Olspert from MPS, who analyzed the data. The Sun, in comparison, rotates rather briskly with a rotation period of only approximately 25 days at the solar equator. The convective turnover times were calculated by means of stellar structure modelling taking into account each star's mass, chemical composition, and evolutionary stage.

The scientists' analysis shows that a star's activity level does not - as had been suggested by other studies based on smaller and more uniform samples including only main sequence stars - depend only on its rotation. Instead, only if convection is accounted for, can the behavior of main-sequence and evolved stars be understood in a unified manner. "The coaction of rotation and convection determine how active a star is", Prof. Käpylä summarizes. "Our results tip the scales in favor of the dynamo mechanism including turbulent convection", she adds.

Numerical simulations showed that the temperature gradient in the disk of gas around a young gas giant planet could play a critical role in the development of a satellite system dominated by a single large moon, similar to Titan around Saturn. Researchers found that dust in the circumplanetary disk can create a "safety zone," which keeps the moon from falling into the planet as the system evolves.

Astronomers believe that many of the moons we see in the Solar System, especially large moons, formed along with the parent planet. In this scenario, moons form from the gas and dust spinning around the still forming planet. But previous simulations have resulted in either all large moons falling into the planet and being swallowed-up or in multiple large moons remaining. The situation we observe around Saturn, with many small moons but only one large moon, does not fit in either of these models.

Yuri Fujii, a Designated Assistant Professor at Nagoya University, and Masahiro Ogihara, a Project Assistant Professor at the National Astronomical Observatory of Japan (NAOJ), created a new model of circumplanetary disks with a more realistic temperature distribution by considering multiple sources of opacities including dust and ice. Then, they simulated the orbital migration of moons considering pressure from disk gas and the gravity of other satellites.

Their simulations show that there is a "safety zone" where a moon is pushed away from the planet. In this area, warmer gas inside the orbit pushes the satellite outward and prevents it from falling into the planet.

"We demonstrated for the first time that a system with only one large moon around a giant planet can form," says Fujii. "This is an important milestone to understand the origin of Titan."

But Ogihara cautions, "It would be difficult to examine whether Titan actually experienced this process. Our scenario could be verified through research of satellites around extrasolar planets. If many single-exomoon systems are found, the formation mechanisms of such systems will become a red-hot issue."

These results were published as Fujii and Ogihara "Formation of single-moon systems around gas giants" in Astronomy and Astrophysics Letters in March 2020. The simulations in this research used the PC Cluster operated by NAOJ.

An international team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has captured the very moment when an old star first starts to alter its environment. The star has ejected high-speed bipolar gas jets which are now colliding with the surrounding material; the age of the observed jet is estimated to be less than 60 years. These features help scientists understand how the complex shapes of planetary nebulae are formed.

Sun-like stars evolve to puffed-up Red Giants in the final stage of their lives. Then, the star expels gas to form a remnant called a planetary nebula. There is a wide variety in the shapes of planetary nebulae; some are spherical, but others are bipolar or show complicated structures. Astronomers are interested in the origins of this variety, but the thick dust and gas expelled by an old star obscure the system and make it difficult to investigate the inner-workings of the process.

To tackle this problem, a team of astronomers led by Daniel Tafoya at Chalmers University of Technology, Sweden, pointed ALMA at W43A, an old star system around 7000 light years from Earth in the constellation Aquila, the Eagle.

Thanks to ALMA's high resolution, the team obtained a very detailed view of the space around W43A. "The most notable structures are its small bipolar jets," says Tafoya, the lead author of the research paper published by the Astrophysical Journal Letters. The team found that the velocity of the jets is as high as 175 km per second, which is much higher than previous estimations. Based on this speed and the size of the jets, the team calculated the age of the jets to be less than a human life-span.

"Considering the youth of the jets compared to the overall lifetime of a star, it is safe to say we are witnessing the 'exact moment' that the jets have just started to push through the surrounding gas," explains Tafoya. "The jets carve through the surrounding material in as little as 60 years. A person could watch their progress throughout their lifetime."

In fact, the ALMA image clearly maps the distribution of dusty clouds entrained by the jets, which is telltale evidence that it is impacting on the surroundings.

The team suggests how this entrainment could be the key to formimg a bipolar-shaped planetary nebula. In their scenario, the aged star originally ejects gas spherically and the core of the star loses its envelope. If the star has a companion, gas from the companion pours onto the core of the dying star, and a portion of this new gas forms the jets. Therefore, whether or not the old star has a companion is an important factor to determine the structure of the resulting planetary nebula.

"W43A is one of the peculiar so called 'water fountain' objects," says Hiroshi Imai at Kagoshima University, Japan, a member of the team. "These are old stars which show characteristic radio emission from water molecules. Our ALMA observations lead us to think that the water heated to generate the radio emission is located the interface region between the jets and the surrounding material. Perhaps all these 'water fountain' sources consist of a central binary system which has just launched a new, double jet, just like W43A."

The team are already working on new ALMA observations of other, similar stars. They are hoping to gain new insight into how planetary nebulae form, and what lies in the future for stars like the Sun.

"There are only 15 'water fountain' objects identified to date, despite the fact that more than 100 billion stars are included in our Milky Way Galaxy," explains José Francisco Gómez at Instituto de Astrofísica de Andalucía, Spain. "This is probably because the lifetime of the jets is quite short, so we are very lucky to see such rare objects."

Monash University researchers have revealed a novel therapy that corrects the mechanism in the body that's gone wrong in Postural Orthostatic Tachycardia Syndrome (POTS), the condition affecting the former lead singer of The Wiggles.

Central Clinical School (CCS) researchers led by Professor Sam El-Osta found how genes that protect against POTS become silent or 'switched off' - and identified a drug to switch them on again.

POTS is one of a group of disorders that have orthostatic intolerance as their primary symptom, in which a greatly reduced volume of blood returns to the heart after the person stands up from a lying-down position. The main symptom of POTS is fainting. Other symptoms include feeling light-headed, fatigue, sweating, shortness of breath and in some cases chest pain and heart palpitations.

In Australia, POTS has become referred to as 'Wiggles Disease' after Greg Page AM retired from the popular children's music group in late 2006 after developing the condition. The 'Yellow Wiggle' recently suffered a heart attack at a charity concert in Sydney likely to be a complication of POTS.

Professor El-Osta said that while the gene implicated in POTS - norepinephrine transporter (NET) - had been known for several decades, past research had failed to find a genetic mutation responsible for the symptoms.

The study, published today in the highly regarded American Heart Association journal Circulation Research, revealed that the enzyme EZH2 is responsible for silencing this gene.

"We predicted that inhibiting this epigenetic condition could reactivate NET gene function and used a pharmacological drug called GSK-126 that could specifically inhibit EZH2 activity with dramatic results," he said. "This is the first description of NET reactivation using a drug. The beauty is that it allows us to target very specifically the enzyme to reactivate gene function."

Currently there is no specific pharmacological treatment available for POTS, which affects mainly people aged 18 to 50 years, eighty per cent of whom are women. "We're far from it now and clinical trials would need to be conducted but the new drug could lead to better management of POTS," he said.

Professor El-Osta's team conducted ex vivo studies isolating blood cells from patients with POTS who failed to respond to current treatments and cells from healthy donors. He said the sample group was relatively small. "Ideally, we'd like to see the work expanded in Australia and overseas and to have our findings validated."

Betelgeuse has been the center of significant media attention lately. The red supergiant is nearing the end of its life, and when a star over 10 times the mass of the Sun dies, it goes out in spectacular fashion. With its brightness recently dipping to the lowest point in the last hundred years, many space enthusiasts are excited that Betelgeuse may soon go supernova, exploding in a dazzling display that could be visible even in daylight.

While the famous star in Orion's shoulder will likely meet its demise within the next million years -- practically couple days in cosmic time -- scientists maintain that its dimming is due to the star pulsating. The phenomenon is relatively common among red supergiants, and Betelgeuse has been known for decades to be in this group.

Coincidentally, researchers at UC Santa Barbara have already made predictions about the brightness of the supernova that would result when a pulsating star like Betelgeuse explodes.

Physics graduate student Jared Goldberg has published a study with Lars Bildsten, director of the campus's Kavli Institute for Theoretical Physics (KITP) and Gluck Professor of Physics, and KITP Senior Fellow Bill Paxton detailing how a star's pulsation will affect the ensuing explosion when it does reach the end. The paper appears in the Astrophysical Journal.

"We wanted to know what it looks like if a pulsating star explodes at different phases of pulsation," said Goldberg, a National Science Foundation graduate research fellow. "Earlier models are simpler because they don't include the time-dependent effects of pulsations."

When a star the size of Betelgeuse finally runs out of material to fuse in its center, it loses the outward pressure that kept it from collapsing under its own immense weight. The resultant core collapse happens in half a second, far faster than it takes the star's surface and puffy outer layers to notice.

As the iron core collapses the atoms disassociate into electrons and protons. These combine to form neutrons, and in the process release high-energy particles called neutrinos. Normally, neutrinos barely interact with other matter -- 100 trillion of them pass through your body every second without a single collision. That said, supernovae are among the most powerful phenomena in the universe. The numbers and energies of the neutrinos produced in the core collapse are so immense that even though only a tiny fraction collides with the stellar material, it's generally more than enough to launch a shockwave capable of exploding the star.

That resulting explosion smacks into the star's outer layers with stupefying energy, creating a burst that can briefly outshine an entire galaxy. The explosion remains bright for around 100 days, since the radiation can escape only once ionized hydrogen recombines with lost electrons to become neutral again. This proceeds from the outside in, meaning that astronomers see deeper into the supernova as time goes on until finally the light from the center can escape. At that point, all that's left is the dim glow of radioactive fallout, which can continue to shine for years.

A supernova's characteristics vary with the star's mass, total explosion energy and, importantly, its radius. This means Betelgeuse's pulsation makes predicting how it will explode rather more complicated.

The researchers found that if the entire star is pulsating in unison -- breathing in and out, if you will -- the supernova will behave as though Betelgeuse was a static star with a given radius. However, different layers of the star can oscillate opposite each other: the outer layers expand while the middle layers contract, and vice versa.

For the simple pulsation case, the team's model yielded similar results to the models that didn't account for pulsation. "It just looks like a supernova from a bigger star or a smaller star at different points in the pulsation," Goldberg explained. "It's when you start considering pulsations that are more complicated, where there's stuff moving in at the same time as stuff moving out -- then our model actually does produce noticeable differences," he said.

In these cases, the researchers discovered that as light leaks out from progressively deeper layers of the explosion, the emissions would appear as though they were the result of supernovae from different sized stars.

"Light from the part of the star that is compressed is fainter," Goldberg explained, "just as we would expect from a more compact, non-pulsating star." Meanwhile, light from parts of the star that were expanding at the time would appear brighter, as though it came from a larger, non-pulsating star.

Goldberg plans to submit a report to Research Notes of the American Astronomical Society with Andy Howell, a professor of physics, and KITP postdoctoral researcher Evan Bauer summarizing the results of simulations they ran specifically on Betelgeuse. Goldberg is also working with KITP postdoc Benny Tsang to compare different radiative transfer techniques for supernovae, and with physics graduate student Daichi Hiramatsu on comparing theoretical explosion models to supernova observations.

Researchers at the Paul Scherrer Institute PSI have measured a property of the neutron more precisely than ever before. In the process they found out that the elementary particle has a significantly smaller electric dipole moment than was previously assumed. With that, it has also become less likely that this dipole moment can help to explain the origin of all matter in the universe. The researchers achieved this result using the ultracold neutron source at PSI. They report their results today in the journal Physical Review Letters.

The Big Bang created both the matter in the universe and the antimatter - at least according to the established theory. Since the two mutually annihilate each other, however, there must have been a surplus of matter, which has remained to this day. The cause of this excess of matter is one of the great mysteries of physics and astronomy. Researchers hope to find a clue to the underlying phenomenon with the help of neutrons, the electrically uncharged elementary building blocks of atoms. The assumption: If the neutron had a so-called electric dipole moment (abbreviated nEDM) with a measurable non-zero value, this could be due to the same physical principle that would also explain the excess of matter after the Big Bang.

50,000 measurements

The search for the nEDM can be expressed in everyday language as the question of whether or not the neutron is an electric compass. It has long been clear that the neutron is a magnetic compass and reacts to a magnetic field, or, in technical jargon: has a magnetic dipole moment. If in addition the neutron also had an electric dipole moment, its value would be very much less - and thus much more difficult to measure. Previous measurements by other researchers have borne this out. Therefore, the researchers at PSI had to go to great lengths to keep the local magnetic field very constant during their latest measurement. Every truck that drove by on the road next to PSI disturbed the magnetic field on a scale that was relevant for the experiment, so this effect had to be calculated and removed from the experimental data.

Also, the number of neutrons observed needed to be large enough to provide a chance to measure the nEDM. The measurements at PSI therefore ran over a period of two years. So-called ultracold neutrons, that is, neutrons with a comparatively slow speed, were measured. Every 300 seconds, an 8 second long bundle with over 10,000 neutrons was directed to the experiment and examined. The researchers measured a total of 50,000 such bundles.

"Even for PSI with its large research facilities, this was a fairly extensive study," says Philipp Schmidt-Wellenburg, a researcher on the nEDM project on the part of PSI. "But that is exactly what is needed these days if we are looking for physics beyond the Standard Model."

Search for "new physics"

The new result was determined by a group of researchers at 18 institutes and universities in Europe and the USA, amongst them the ETH Zurich, the University of Bern and the University of Fribourg. The data had been gathered at PSI's ultracold neutron source. The researchers had collected measurement data there over two years, evaluated it very carefully in two teams, and through that obtained a more accurate result than ever before.

The nEDM research project is part of the search for "new physics" that would go beyond the so-called Standard Model. This is also being sought at even larger facilities such as the Large Hadron Collider LHC at CERN. "The research at CERN is broad and generally searches for new particles and their properties", explains Schmidt-Wellenburg. "We on the other hand are going deep, because we are only looking at the properties of one particle, the neutron. In exchange, however, we achieve an accuracy in this detail that the LHC might only reach in 100 years."

"Ultimately", says Georg Bison, who like Schmidt-Wellenburg is a researcher in the Laboratory for Particle Physics at PSI, "various measurements on the cosmological scale show deviations from the Standard Model. In contrast, no one has yet been able to reproduce these results in the laboratory. This is one of the very big questions in modern physics, and that's what makes our work so exciting."

Even more precise measurements are planned

With their latest experiment, the researchers have confirmed previous laboratory results. "Our current result too yielded a value for nEDM that is too small to measure with the instruments that have been used up to now - the value is too close to zero", says Schmidt-Wellenburg. "So it has become less likely that the neutron will help explain the excess of matter. But it still can't be completely ruled out. And in any case, science is interested in the exact value of the nEDM in order to find out if it can be used to discover new physics."

Therefore, the next, more precise measurement is already being planned. "When we started up the current source for ultracold neutrons here at PSI in 2010, we already knew that the rest of the experiment wouldn't quite do it justice. So we are currently building an appropriately larger experiment", explains Bison. The PSI researchers expect to start the next series of measurements of the nEDM by 2021 and, in turn, to surpass the current one in terms of accuracy.

"We have gained a great deal of experience in the past ten years and have been able to use it to continuously optimise our experiment - both with regard to our neutron source and in general for the best possible evaluation of such complex data in particle physics", says Schmidt-Wellenburg. "The current publication has set a new international standard."

Knots are all around us: in computer cables, headphones and wires. But, although they can be a nuisance, they're also very useful when it comes to tying up your laces or when you go sailing. In maths, there are no less than six billion different potential knots, but what about knots in chemistry? Since the 1970s, scientists have been trying to knot molecules together to create new, custom-made mechanical properties, which will give rise to new materials. The first successes took place twenty years later but the process remains laborious. Today, researchers from the University of Geneva (UNIGE), Switzerland, have developed a simple and effective technique for tying knots in molecules, and have for the first time observed the changes in properties that result from these interlockings. The results, which you can read about in the journal Chemistry - A European Journal, open up new perspectives for designing materials and transferring information molecularly.

Knots are certainly useful. But what about in chemistry? Is it possible to tie molecules together? The idea first made an appearance in 1971 with the aim of creating new materials induced by the changes in mechanical and physical properties that would result from these interlockings. But it was not until 1989 that Jean-Pierre Sauvage, the French 2016 Nobel Prize winner in chemistry, succeeded. Scientists have subsequently worked hard at trying to form knots but it remains challenging: "To tie molecules together, you have to use metals that attach to the molecules and direct them on a very specific path forming the intersections that are needed to make knots", explains Fabien Cougnon, a researcher in the Organic Chemistry Department in UNIGE's Faculty of Sciences. "But it is a complex process that often results in a loss of raw material of over 90%! The resulting amount of molecular knots is typically only a few milligrams at most, not enough to make new materials."

Hydrophobic molecules that tie together on their own

The UNIGE chemists developed a new technique that makes it possible to create interlocked molecules easily. "We use fatty molecules that we soak in water heated to 70 degrees. Since they are hydrophobic, they try to escape the water at all costs, gathering together and forming a knot by means of self-assembly", says Tatu Kumpulainen, a researcher in the Physical Chemistry Department in UNIGE's Faculty of Sciences.

Thanks to this new technique, the Geneva-based chemists can make molecular knots effortlessly, and - even more importantly - without losing any material. "We transform up to 90% of the basic reagents into knots, which means we can consider a real analysis of the changes in the mechanical properties induced by the knots, which has never been done before!" notes Cougnon. Although they cannot choose how the molecules are knotted together, they are able to reproduce the same knot at will, because the same chemical structure will always form an identical knot in aqueous environment.

Each knot has its own mechanical properties

Now that knotting molecules has become easy, what can we do with these knots? Is there any value in forming them? To check the impact of the interlockings, the Geneva chemists chose a family of molecules that all have the same design: they absorb ultraviolet, are fluorescent and are highly sensitive to the general environment, especially the presence of water. "We created four knots, from the simplest to the most complex (0, 2, 3 and 4 intersections), which we compared to a reference molecule which constitutes their basis,» explains Cougnon. "To do this, we first used nuclear magnetic resonance (NMR) to observe the stiffness of the different parts of the knots and the speed and way they move relative to one another." The scientists found a first change in mechanical properties: the more complex the knots are, the less they move.

The chemists subsequently used spectroscopy to compare the spectra of the four knots with each other. "We soon noticed that the looser single knots (0 and 2 intersections) behaved in the same way as the reference molecule", continues Kumpulainen. "But when the knots are more complex, the molecules - which were tighter - changed their physical properties and colour! Their way of absorbing and emitting light differed from the reference molecule." This change in colour means that the scientists can visualise the mechanical properties specific to each assembly, whether it is its elasticity, structure, movement or position.

For the first time, the Geneva chemists have shown that knotted molecules change mechanical properties. "We now want to be able to control these changes from A to Z so that we can use these knots, for example, as indicators for the properties of the environment", says Kumpulainen. They also plan to build new materials, such as elastics, using the networks of knots now that there is no loss of material when making the intersections. "At last, we can consider transferring information inside a knot thanks to a simple change of position on a part of the knot which would be reflected throughout the structure and would convey the information", concludes Cougnon.

Most ordinary matter is held together by an invisible subatomic glue known as the strong nuclear force -- one of the four fundamental forces in nature, along with gravity, electromagnetism, and the weak force. The strong nuclear force is responsible for the push and pull between protons and neutrons in an atom's nucleus, which keeps an atom from collapsing in on itself.

In atomic nuclei, most protons and neutrons are far enough apart that physicists can accurately predict their interactions. However, these predictions are challenged when the subatomic particles are so close as to be practically on top of each other.

While such ultrashort-distance interactions are rare in most matter on Earth, they define the cores of neutron stars and other extremely dense astrophysical objects. Since scientists first began exploring nuclear physics, they have struggled to explain how the strong nuclear force plays out at such ultrashort distances.

Now physicists at MIT and elsewhere have for the first time characterized the strong nuclear force, and the interactions between protons and neutrons, at extremely short distances.

They performed an extensive data analysis on previous particle accelerator experiments, and found that as the distance between protons and neutrons becomes shorter, a surprising transition occurs in their interactions. Where at large distances, the strong nuclear force acts primarily to attract a proton to a neutron, at very short distances, the force becomes essentially indiscriminate: Interactions can occur not just to attract a proton to a neutron, but also to repel, or push apart pairs of neutrons.

"This is the first very detailed look at what happens to the strong nuclear force at very short distances," says Or Hen, assistant professor of physicist at MIT. "This has huge implications, primarily for neutron stars and also for the understanding of nuclear systems as a whole."

Hen and his colleagues have published their results in the journal Nature. His co-authors include first author Axel Schmidt PhD '16, a former graduate student and postdoc, along with graduate student Jackson Pybus, undergraduate student Adin Hrnjic and additional colleagues from MIT, the Hebrew University, Tel-Aviv University, Old Dominion University, and members of the CLAS Collaboration, a multi-institutional group of scientists involved with the CEBAF Large Accelerator Spectrometer (CLAS), a particle accelerator at Jefferson Laboratory in Newport News, Virginia.

Star drop snapshot

Ultra-short-distance interactions between protons and neutrons are rare in most atomic nuclei. Detecting them requires pummeling atoms with a huge number of extremely high-energy electrons, a fraction of which might have a chance of kicking out a pair of nucleons (protons or neutrons) moving at high momentum -- an indication that the particles must be interacting at extremely short distances.

"To do these experiments, you need insanely high-current particle accelerators," Hen says. "It's only recently where we have the detector capability, and understand the processes well enough to do this type of work."

Hen and his colleagues looked for the interactions by mining data previously collected by CLAS, a house-sized particle detector at Jefferson Laboratory; the JLab accelerator produces unprecedently high intensity and high-energy beams of electrons. The CLAS detector was operational from 1988 to 2012, and the results of those experiments have since been available for researchers to look through for other phenomena buried in the data.

In their new study, the researchers analyzed a trove of data, amounting to some quadrillion electrons hitting atomic nuclei in the CLAS detector. The electron beam was aimed at foils made from carbon, lead, aluminum, and iron, each with atoms of varying ratios of protons to neutrons. When an electron collides with a proton or neutron in an atom, the energy at which it scatters away is proportional to the energy and momentum of the corresponding nucleon.

"If I know how hard I kicked something and how fast it came out, I can reconstruct the initial momentum of the thing that was kicked," Hen explains.

With this general approach, the team looked through the quadrillion electron collisions and managed to isolate and calculate the momentum of several hundred pairs of high-momentum nucleons. Hen likens these pairs to "neutron star droplets," as their momentum, and their inferred distance between each other, is similar to the extremely dense conditions in the core of a neutron star.

They treated each isolated pair as a "snapshot" and organized the several hundred snapshots along a momentum distribution. At the low end of this distribution, they observed a suppression of proton-proton pairs, indicating that the strong nuclear force acts mostly to attract protons to neutrons at intermediate high-momentum, and short distances.

Further along the distribution, they observed a transition: There appeared to be more proton-proton and, by symmetry, neutron-neutron pairs, suggesting that, at higher momentum, or increasingly short distances, the strong nuclear force acts not just on protons and neutrons, but also on protons and protons and neutrons and neutrons. This pairing force is understood to be repulsive in nature, meaning that at short distances, neutrons interact by strongly repelling each other.

"This idea of a repulsive core in the strong nuclear force is something thrown around as this mythical thing that exists, but we don't know how to get there, like this portal from another realm," Schmidt says. "And now we have data where this transition is staring us in the face, and that was really surprising."

The researchers believe this transition in the strong nuclear force can help to better define the structure of a neutron star. Hen previously found evidence that in the outer core of neutron stars, neutrons mostly pair with protons through the strong attraction. With their new study, the researchers have found evidence that when particles are packed in much denser configurations and separated by shorter distances, the strong nuclear force creates a repulsive force between neutrons that, at a neutron star's core, helps keep the star from collapsing in on itself.

Less than a bag of quarks

The team made two additional discoveries. For one, their observations match the predictions of a surprisingly simple model describing the formation of short-ranged correlations due to the strong nuclear force. For another, against expectations, the core of a neutron star can be described strictly by the interactions between protons and neutrons, without needing to explicitly account for more complex interactions between the quarks and gluons that make up individual nucleons.

When the researchers compared their observations with several existing models of the strong nuclear force, they found a remarkable match with predictions from Argonne V18, a model developed by a research group at Argonne National Laboratory, that considered 18 different ways nucleons may interact, as they are separated by shorter and shorter distances.

This means that if scientists want to calculate properties of a neutron star, Hen says they can use this particular Argonne V18 model to accurately estimate the strong nuclear force interactions between pairs of nucleons in the core. The new data can also be used to benchmark alternate approaches to modeling the cores of neutron stars.

What the researchers found most exciting was that this same model, as it is written, describes the interaction of nucleons at extremely short distances, without explicitly taking into account quarks and gluons. Physicists had assumed that in extremely dense, chaotic environments such as neutron star cores, interactions between neutrons should give way to the more complex forces between quarks and gluons. Because the model does not take these more complex interactions into account, and because its predictions at short distances match the team's observations, Hen says it's likely that a neutron star's core can be described in a less complicated manner.

"People assumed that the system is so dense that it should be considered as a soup of quarks and gluons," Hen explains. "But we find even at the highest densities, we can describe these interactions using protons and neutrons; they seem to keep their identities and don't turn into this bag of quarks. So the cores of neutron stars could be much simpler than people thought. That's a huge surprise."

The SEIS seismometer from NASA's InSight mission measured a total of 174 probable 'Mars quakes' in the first months since its launch at the end of February 2019. That is slightly more than one quake every two days. These data provide the first comprehensive proof that - besides the Earth and the Moon - Mars is also seismically active. The data, which were generated with the participation of Cologne-based researcher Dr Brigitte Knapmeyer-Endrun from the University of Cologne's Institute of Geology and Mineralogy, have been published in Nature Geoscience and Nature Communications.

Martian quakes are not as frequent and not as strong as earthquakes. None of the quakes reached a magnitude of 4. On Earth, such quakes would be perceptible for measuring instruments or even people in the immediate vicinity, but they would not cause any damage. However, even the weak Mars quakes provide valuable data on the planet's composition. 'This is the first time seismology was conducted on Mars. The new data therefore give us completely new insights into the structure of the planet', says Knapmeyer-Endrun, who contributed to developing the Mars seismometer. She is now researching the structure of the Red Planet's crust.

Scientists assume that Mars - similar to Earth - has an onion-like structure. The core is enveloped in a rock mantle and a crust on the very outside. Seismological measurements can provide important information about the composition and thickness of the various layers. An earthquake creates waves that run along the surface and waves that go through the interior of the planet. They pass through the layers at different speeds and are refracted and reflected at the boundaries. When and where the waves reach the surface therefore allows for inferences about the inner structure of the planet.

The scientists are optimistic that an analysis of the Mars quakes will provide such information. 'A first result indicates a layer of rock 10 kilometres thick, in which the waves spread at relatively slow speeds. We therefore assume that this layer is not composed of intact basalt, but fissured or chemically altered rock', says Knapmeyer-Endrun.

Quakes similar to those on Mars occur on Earth more than a thousand times a year. One explanation for the relative weakness of these quakes could be that Mars, unlike Earth, probably consists of only one continuous tectonic plate. On Earth, on the other hand, tensions that build up and then erupt between adjacent plates generate most of the strong quakes.

To find out more about the deeper interior of Mars, the InSight mission's researchers hope for a stronger quake in the coming months. On Earth, violent tremors occasionally occur even within a tectonic plate. The waves they trigger penetrate deeper into the planet - with a little luck even to the core.

The first reports of seismic activity and ground vibrations on Mars are in. The red planet has a moderate level of seismic activity, intermediate between Earth and the Moon.

An international team that includes University of Maryland geologists released preliminary results from the InSight mission, which landed a probe on Mars on November 26, 2018. Data from the mission's Seismic Experiment for Interior Structure (SEIS) provided the first direct seismic measurements of the Martian subsurface and upper crust--the rocky outermost layer of the planet. The results were published in a special issue of the journal Nature Geoscience on February 24, 2020.

"This is the first mission focused on taking direct geophysical measurements of any planet besides Earth, and it's given us our first real understanding of Mars' interior structure and geological processes," said Nicholas Schmerr, an assistant professor of geology at UMD and a co-author of the study. "These data are helping us understand how the planet works, its rate of seismicity, how active it is and where it's active."

The seismic data acquired over 235 Martian days showed 174 seismic events, or marsquakes. Of those, 150 were high-frequency events that produce ground shaking similar to that recorded on the Moon by the Apollo program. Their waveforms show that seismic waves bounce around as they travel through the heterogeneous and fractured Martian crust. The other 24 quakes observed by SEIS were predominantly low-frequency events. Three showed two distinct wave patterns similar to quakes on Earth caused by the movement of tectonic plates.

"These low-frequency events were really exciting, because we know how to analyze them and extract information about subsurface structure," said Vedran Lekic, an associate professor of geology at UMD and a co-author of the study. "Based on how the different waves propagate through the crust, we can identify geologic layers within the planet and determine the distance and location to the source of the quakes."

The researchers identified the source location and magnitude of three of the low-frequency marsquakes, and believe that 10 more are strong enough to reveal their source and magnitude once they are analyzed.

"Understanding these processes is part of a bigger question about the planet itself," Schmerr said. "Can it support life, or did it ever? Life exists at the edge, where the equilibrium is off. Think of areas on Earth such as the thermal vents at the deep ocean ridges where chemistry provides the energy for life rather than the sun. If it turns out there is liquid magma on Mars, and if we can pinpoint where the planet is most geologically active, it might guide future missions searching for the potential for life."

Detecting signs of life was the primary mission of the earlier Mars probes, Viking 1 and Viking 2. Each carried seismometers, but they were mounted directly on the landers and provided no useful data. The Viking 1 instrument did not unlock properly, and Viking 2 only picked up noise from wind buffeting the lander but no convincing marsquake signals.

The InSight mission is dedicated specifically to geophysical exploration, so engineers worked to solve previous noise problems. A robotic arm on the lander placed the SEIS seismometer directly on the Martian ground some distance away to isolate it from the lander. The instrument is also housed in a vacuum chamber and covered by the aptly named Wind and Thermal Shield. The SEIS seismometer is sensitive enough to discern very faint ground vibrations, which on Mars are 500 times quieter than ground vibrations found in quietest locations on Earth.

In addition, the seismometer provided important information about Martian weather. Low-pressure systems and swirling columns of wind and dust called dust devils lift the ground enough for the seismometer to register a tilt in the substrate. High winds flowing across the surface of the ground also create a distinct seismic signature. Combined with data from meteorological instruments, SEIS data help paint a picture of the daily cycles of surface activity near the InSight lander.

The researchers found that the winds pick up from about midnight through early morning, as cooler air rolls down from highlands in the Southern Hemisphere onto the Elysium Planitia plains in the Northern Hemisphere where the lander is located. During the day, heating from the sun causes convective winds to build. Winds reach their peak in late afternoon when atmospheric pressure drops and dust devil activity occurs. By evening, the winds die down, and conditions around the lander become quiet. From late evening until about midnight, atmospheric conditions are so quiet, the seismometer is able to detect the rumblings from deeper inside the planet.

All of the marsquakes have been detected during these quiet periods at night, but the geologic activity likely persists throughout the day.

"What is so spectacular about this data is that it gives us this beautifully poetic picture of what a day is actually like on another planet," Lekic said.

The InSight mission is scheduled to continue collecting data through 2020.

Feb. 21, 2020- Traditional stoves that burn biomass materials and are not properly ventilated, which are widely used in developing nations where cooking is done indoors, have been shown to significantly increase indoor levels of harmful PM2.5 (miniscule atmospheric particulates) and carbon monoxide (CO) and to stimulate biological processes that cause lung inflammation and may lead to chronic obstructive pulmonary disease (COPD), according to new research published online in the Annals of the American Thoracic Society.

In "Pro-Inflammatory Effects in Ex Vivo Human Lung Tissue of Respirable Smoke Extracts from Indoor Cooking in Nepal," Professor Ian P. Hall of the University of Nottingham, UK led a study of the pulmonary effects of traditional cook stoves (TCS), in comparison with improved, ventilated stoves (ICS) and liquid petroleum gas (LPG) stoves. Field research was led by Siva Praveen Puppala, PhD, of Nepal's International Centre for Integrated Mountain Development.

Why conduct the study in Nepal? "I have had links with Dhulikhel Hospital in Kathmandu for seven years," Prof. Hall explained. "When on hospital rounds, I noticed a lot of admissions for COPD, both men and women. Nepalese men smoke, but women generally don't, while they are also traditionally the family cooks. I was interested in why women were getting COPD, and the most obvious question to explore was whether it was due to indoor biomass smoke, so we decided to study these exposures."

The researchers measured personal exposures to PM2.5 and CO during cooking on a range of stoves in 103 households in four different Nepalese villages, each village at a different elevation (from 200 to 4,000 meters above sea level), and took measurements outdoors as well as indoors when cooking was not being done. They also exposed surgically removed lung tissue to soluble smoke samples collected during cooking, and then applied the samples to the tissue and tested it for 17 different inflammatory substances. There would not be any CO in these extracts, so the researchers only looked at other components of the extracts.

Increased levels of 7 of 17 inflammatory substances occurred in the lung tissue following TCS biomass smoke exposure. Cooking with the improved cook stove still caused an inflammatory response related to six of these substances. LPG cooking activated two inflammatory substances. Study authors believe these elevated levels during ICS and LPG cooking may be due to inflammation-causing substances not tested for.

"Little was previously known about the mechanisms underlying the lung's response to biomass smoke," said Dr. Hall. "Now, we have shown, for the first time, that biomass smoke samples collected in a real-life environment from rural Nepal have pro-inflammatory effects on human lung tissue. These exposures, which induce lung inflammation, may partially explain the increased risk of COPD in these communities."

Lung inflammation is a major cause of COPD. More than 90 percent of deaths from COPD are in low and middle-income countries, and COPD has a high incidence rate in the regions of Nepal studied.

The researchers found that the overall average PM2.5 exposure was reduced by 51 percent in homes that used ICS and by 80 percent in households using LPG stoves, in comparison with traditional stoves. Exposures to particulates in different locations while cooking with traditional stoves were 5-29 fold higher than 24-hour World Health Organization (WHO) exposure standards. Even the reduced exposures to PM2.5 using either ICS or LPG were higher than WHO recommended levels. Higher particulate levels were also found in higher elevations.

The indoor CO concentration was reduced by 72 percent and 86 percent, respectively, in households using ICS and LPG. All cooks who used TCS exhaled higher levels of CO while they were cooking than when they were not.

The traditional biomass stoves, which are used by 80 percent of the Nepalese population and widely used in low and middle-income nations throughout the developing world, burn wood, crop residues or dried dung. Cooking is done on open fires in rooms without a chimney or proper ventilation. Improved biomass stoves, which have improved compression systems and/or vent fumes through a chimney, have been tried in some villages. Twenty-one percent of Nepalese homes use liquefied petroleum gas stoves, which burn a mixture of propane, butane and isobutane.

"These data support the need to reduce exposures in order to improve respiratory health in this setting," stated Dr. Hall. "Additional methods other than those being tried may be needed to reduce exposures to levels that will prevent lung inflammation and reduce the risk of developing COPD."

Astronomers from the University of Warwick have observed an exoplanet orbiting a star in just over 18 hours, the shortest orbital period ever observed for a planet of its type.

It means that a single year for this hot Jupiter - a gas giant similar in size and composition to Jupiter in our own solar system - passes in less than a day of Earth time.

The discovery is detailed in a new paper published today (20 February) for the Monthly Notices of the Royal Astronomical Society and the scientists believe that it may help to solve a mystery of whether or not such planets are in the process of spiralling towards their suns to their destruction.

The planet NGTS-10b was discovered around 1000 light years away from Earth as part of the Next-Generation Transit Survey (NGTS), an exoplanet survey based in Chile that aims to discover planets down to the size of Neptune using the transit method. This involves observing stars for a telltale dip in brightness that indicates that a planet has passed in front of it.

At any one time the survey observes 100 square degrees of sky which includes around 100,000 stars. Out of those 100,000 stars this one caught the astronomers' eye due to the very frequent dips in the star's light caused by the planet's rapid orbit.

Lead author Dr James McCormac from the University of Warwick Department of Physics said: "We're excited to announce the discovery of NGTS-10b, an extremely short period Jupiter-sized planet orbiting a star not too dissimilar from our Sun. We are also pleased that NGTS continues to push the boundaries in ground-based transiting exoplanet science through the discovery of rare classes of exoplanets.

"Although in theory hot Jupiters with short orbital periods (less than 24 hours) are the easiest to detect due to their large size and frequent transits, they have proven to be extremely rare. Of the hundreds of hot Jupiters currently known there are only seven that have an orbital period of less than one day."

NGTS-10b orbits so rapidly because it is very close to its sun - only twice the diameter of the star which, in the context of our solar system, would locate it 27 times closer than Mercury is to our own Sun. The scientists have noted that it is perilously close to the point that tidal forces from the star would eventually tear the planet apart.

The planet is likely tidally locked so one side of the planet is constantly facing the star and constantly hot - the astronomers estimate the average temperature to be more than 1000 degrees Celsius. The star itself is around 70% the radius of our Sun and 1000 degrees cooler. NGTS-10b is also an excellent candidate for atmospheric characterisation with the upcoming James Webb Space Telescope.

Using transit photometry, the scientists know that the planet is 20% bigger than our Jupiter and just over twice the mass according to radial velocity measurements, caught at a convenient point in its lifecycle to help answer questions about the evolution of such planets.

Massive planets typically form far away from the star and then migrate either through interactions with the disc while the planet is still forming, or from interactions with additional planets much further out later in their life. The astronomers plan to apply for time to get high-precision measurements of NGTS-10b, and to continue observing it over the next decade to determine whether this planet will remain in this orbit for some time to come - or will spiral into the star to its death.

Co-author Dr David Brown adds: "It's thought that these ultra-short planets migrate in from the outer reaches of their solar systems and are eventually consumed or disrupted by the star. We are either very lucky to catch them in this short period orbit, or the processes by which the planet migrates into the star are less efficient than we imagine, in which case it can live in this configuration for a longer period of time."

Co-author Dr Daniel Bayliss said: "Over the next ten years, it might be possible to see this planet spiralling in. We'll be able to use NGTS to monitor this over a decade. If we could see the orbital period start to decrease and the planet start to spiral in, that would tell us a lot about the structure of the planet that we don't know yet.

"Everything that we know about planet formation tells us that planets and stars form at the same time. The best model that we've got suggests that the star is about ten billion years old and we'd assume that the planet is too. Either we are seeing it in the last stages of its life, or somehow it's able to live here longer than it should."

NGTS is situated at the European Southern Observatory's Paranal Observatory in the heart of the Atacama Desert, Chile. It is a collaboration between UK Universities Warwick, Leicester, Cambridge, and Queen's University Belfast, together with Observatoire de Genève, DLR Berlin and Universidad de Chile. In the UK, the facility and the research is supported by the Science and Technologies Facilities Council (STFC) part of UK Research and Innovation (UKRI).

The precursor of our planet, the proto-Earth, formed within a time span of approximately five million years, shows a new study from the Centre for Star and Planet Formation (StarPlan) at the Globe Institute at the University of Copenhagen.

On an astronomical scale, this is extremely fast, the researchers explain.

If you compare the solar system's estimated 4.6 billion years of existence with a 24-hour period, the new results indicate that the proto-Earth formed in what corresponds to about a minute and a half.

Thus, the results from StarPlan break with the traditional theory that the proto-Earth formed by random collisions between larger and larger planetary bodies throughout several tens of millions of years - equivalent to about 5-15 minutes out of the above-mentioned fictional 24 hours of formation.

Instead, the new results support a more recent, alternative theory about the formation of planets through the accretion of cosmic dust. The study's lead author, Associate Professor Martin Schiller, explains it as follows:

'The other idea is that we start from dust, essentially. Millimetre-sized objects, all coming together, raining down on the growing body and making the planet in one go,' he says, adding:

'Not only is this implication of the rapid formation of the Earth interesting for our solar system. It is also interesting to assess how likely it is for planets to form somewhere else in the galaxy.'

The bulk composition of the solar system

The key to the new finding came in the form of the most precise measurements of iron isotopes that have so far been published scientifically.

By studying the isotopic mixture of the metallic element in different meteorites, the researchers found only one type of meteoritic material with a composition similar to Earth: The so-called CI chondrites.

The researchers behind the study describe the dust in this fragile type of meteorite as our best equivalent to the bulk composition of the solar system itself. It was dust like this combined with gas that was funnelled via a circumstellar accretion disk onto the growing Sun.

This process lasted about five million years and our planets were made from material in this disk. Now, the researchers estimate that the proto-Earth's ferrous core also formed already during this period, removing early accreted iron from the mantle.

Two different iron compositions

Other meteorites, for example from Mars, tell us that at the beginning the iron isotopic composition of material contributing to the growing Earth was different. Most likely due to thermal processing of dust close to the young sun, the researchers from StarPlan explain.

After our solar system's first few hundred thousands of years it became cold enough for unprocessed CI dust from further out in the system to enter the accretion region of the proto-Earth.

'This added CI dust overprinted the iron composition in the Earth's mantle, which is only possible if most of the previous iron was already removed into the core. That is why the core formation must have happened early,' Martin Schiller explains.

'If the Earth's formation was a random process where you just smashed bodies together, you would never be able to compare the iron composition of the Earth to only one type of meteorite. You would get a mixture of everything,' he adds.

More planets, more water, perhaps more life

Based on the evidence for the theory that planets form through the accretion of cosmic dust, the researchers believe that the same process may occur elsewhere in the universe.

This means that also other planets may likely form much faster than if they grow solely from random collisions between objects in space.

This assumption is corroborated by the thousands of exoplanets - planets in other galaxies - that astronomers have discovered since the mid-nineties, explains Centre Leader and co-author of the study, Professor Martin Bizzarro:

'Now we know that planet formation happens everywhere. That we have generic mechanisms that work and make planetary systems. When we understand these mechanisms in our own solar system, we might make similar inferences about other planetary systems in the galaxy. Including at which point and how often water is accreted', he says, adding:

'If the theory of early planetary accretion really is correct, water is likely just a by-product of the formation of a planet like the Earth - making the ingredients of life, as we know it, more likely to be found elsewhere in the universe'.

BUFFALO, N.Y. -- Reciprocity isn't always a good thing.

In physics, for example, it concerns electromagnetic and acoustic waves. The idea is that waves travel the same way backward as they do forward. Which is fine, except that waves encounter obstacles (skyscrapers, wind, people) that cause them to lose energy.

But what if you could break that rule and guide waves around those obstacles? Or have an object completely absorb the wave in a specific direction? Such functionalities could alter how electronic, photonic and acoustic devices are designed and used.

University at Buffalo engineers have taken a step in this direction. Working in an emerging field known to as "spacetime-varying metamaterials," engineers have demonstrated the ability to break reciprocity in acoustic waves.

A study describing their work, which is supported by the National Science Foundation, was published Feb. 14 in Physical Review Applied letters, a journal published by the American Physical Society journal.

"We have experimentally demonstrated that it's possible to break reciprocity in acoustic waves with material properties that change simultaneously in time and space," says the project's lead investigator Mostafa Nouh, PhD, assistant professor of mechanical and aerospace engineering in the School of Engineering and Applied Sciences.

Co-authors are M. Ali Attarzadeh and Jesse Callanan, both PhD candidates in Nouh's lab.

To conduct the experiments, Nouh and the students built a beam that consists of a common thermoplastic (acrylonitrile butadiene styrene, or ABS) bar outfitted with 20 aluminum resonators, each shaped like a rectangle.

Motors allow the engineers to program each resonator, which are grouped in pairs of four, to spin at 45-degree angle intervals. For example, the first resonator is at 0 degrees, the second at 45 degrees, the third at 90 degrees and the fourth at 135 degrees. The next group of four follows the same pattern, and so on.

The spin is both a function of space (the 45-degree intervals) and time (the milliseconds between their angular orientations). Hence the name, spacetime-varying metamaterials.

When activated, the spinning resonators look like car pistons that twirl instead of pumping up and down. What they're doing, however, is changing the beam's "stiffness," which is its resistance to being deformed by an applied force.

This video explains in greater detail how the system works.

Before testing the beam, the team performed computer simulations that predicted reciprocity would break at very fast variations of stiffness. In other words, the faster the resonators spin, the more likely they could break reciprocity.

So the engineers cranked the motors up to 2,000 revolutions per minute (rpm). To see if this was fast enough, engineers sent vibrations (an acoustic wave) through the beam via a piezolelectric actuator. Using a scanning laser Doppler vibrometer, as well as a thermal imaging camera (to ensure slight temperature fluctuations weren't influencing the experiment), Nouh and students found that the pattern in which the wave returned to its origin widely diverged from its initial course.

"This is evidence of the wave acting in a non-reciprocal manner," says Callanan.

In another test, with the resonators spinning only at 100 rpm, the beam's stiffness barely budged. Nouh and students found that the wave returned back to its point of origin the same way it left, indicating that reciprocity was not broken.

"The experiments not only demonstrate our ability to break the reciprocity of acoustic waves, but confirm our hypothesis that such breakage is contingent on the speed of stiffness modulations through the spinning action," says Attarzadeh.

The ability to manipulate waves in this manner, a first of its kind proof-of-concept, has many possible uses. For example, you could build a wall that allows sound to pass through easily in one direction but not in the opposite way. It could improve how autonomous vehicles communicate with one another. It could increase the resolution of medical imaging via ultrasound, which typically suffers from a limitation called "reflection artifacts" that can lead doctors to misinterpret images.

But Nouh cautions the laboratory achievement is not ready for commercialization yet. For example, the beam the team built is large and would need to be scaled-down, likely through 3D printing or other nanofabrication tools. Also, the materials the team used heat up too quickly. To overcome this, more advanced and more expensive materials are likely needed.

A new study led by the University of Hawai'i (UH) at Mānoa has helped refine understanding of the amount of hydrogen, helium and other elements present in violent outbursts from the Sun, and other types of solar "wind," a stream of ionized atoms ejected from the Sun.

Coronal mass ejections (CME) are giant plasma bursts that erupt from the sun, heading out into the solar system at speeds as fast as 2 million miles per hour. Like the sun itself, the majority of a CME's atoms are hydrogen. When these particles interact with Earth's atmosphere, they lead to the brilliant multicolored lights of the Aurora Borealis. They also have the potential to knock out communications, bringing modern civilization to a standstill.

And their cause is pretty much a mystery.

UH Manoa School of Ocean and Earth Science and Technology (SOEST) researcher Gary Huss led a team of scientists in investigating a sample of solar wind collected by NASA's Genesis mission.

Most of our understanding of the composition of the sun, which makes up 99.8% of the mass of the Solar System, has come from astronomical observations and measurements of a rare type of meteorite. In 2001, the Genesis probe headed to space to gather samples of solar wind in pure materials, and bring the material back to Earth to be studied in a lab. Those samples represented particles gathered from different sources of solar wind, including those thrown off by CMEs.

The Genesis samples allowed for a more accurate assessment of the hydrogen abundance in CMEs and other components of the solar wind. About 91% of the Sun's atoms are hydrogen, so everything that happens in the solar wind plasma is influenced by hydrogen.

However, measuring hydrogen in the Genesis samples proved to be a challenge. An important component of the recent work was to develop appropriate standards using terrestrial minerals with known amounts of hydrogen, implanted with hydrogen by a laboratory accelerator.

A precise determination of the amount of hydrogen in the solar wind allowed researchers to discern small differences in the amount of neon and helium relative to hydrogen ejected by these massive solar ejections. Helium and neon, both noble gases, are difficult to ionize. The new measurements of hydrogen showed that helium and neon were both enriched in coronal mass ejections, providing clues to the underlying physics in the Sun that causes the coronal mass ejections.

In the very energetic event, "the ejected material appears to be enriched almost systematically in atoms that require the most energy to ionize," said Ryan Ogliore, co-author and assistant professor of physics at Washington University in St. Louis. "That tells us a lot about the physics involved in the first stages of the explosion on the Sun."

This finding brings researchers one step closer to understanding the origins of these particular solar events.