Closest known flyby of star to our solar system: Dim star passed through Oort Cloud 70,000 years ago

A group of astronomers from the US, Europe, Chile and South Africa have determined that 70,000 years ago a recently discovered dim star is likely to have passed through the solar system's distant cloud of comets, the Oort Cloud. No other star is known to have ever approached our solar system this close -- five times closer than the current closest star, Proxima Centauri.

In a paper published in The Astrophysical Journal Letters, lead author Eric Mamajek from the University of Rochester and his collaborators analyzed the velocity and trajectory of a low-mass star system nicknamed "Scholz's star."

The star's trajectory suggests that 70,000 years ago it passed roughly 52,000 astronomical units away (or about 0.8 light years, which equals 8 trillion kilometers, or 5 trillion miles). This is astronomically close; our closest neighbor star Proxima Centauri is 4.2 light years distant. In fact, the astronomers explain in the paper that they are 98% certain that it went through what is known as the "outer Oort Cloud" -- a region at the edge of the solar system filled with trillions of comets a mile or more across that are thought to give rise to long-period comets orbiting the Sun after their orbits are perturbed.

The star originally caught Mamajek's attention during a discussion with co-author Valentin D. Ivanov, from the European Southern Observatory. Scholz's star had an unusual mix of characteristics: despite being fairly close ("only" 20 light years away), it showed very slow tangential motion, that is, motion across the sky. The radial velocity measurements taken by Ivanov and collaborators, however, showed the star moving almost directly away from the solar system at considerable speed.

"Most stars this nearby show much larger tangential motion," says Mamajek, associate professor of physics and astronomy at the University of Rochester. "The small tangential motion and proximity initially indicated that the star was most likely either moving towards a future close encounter with the solar system, or it had 'recently' come close to the solar system and was moving away. Sure enough, the radial velocity measurements were consistent with it running away from the Sun's vicinity -- and we realized it must have had a close flyby in the past."

To work out its trajectory the astronomers needed both pieces of data, the tangential velocity and the radial velocity. Ivanov and collaborators had characterized the recently discovered star through measuring its spectrum and radial velocity via Doppler shift. These measurements were carried out using spectrographs on large telescopes in both South Africa and Chile: the Southern African Large Telescope (SALT) and the Magellan telescope at Las Campanas Observatory, respectively.

Once the researchers pieced together all the information they figured out that Scholz's star was moving away from our solar system and traced it back in time to its position 70,000 years ago, when their models indicated it came closest to our Sun. Until now, the top candidate for the closest flyby of a star to the solar system was the so-called "rogue star" HIP 85605, which was predicted to come close to our solar system in 240,000 to 470,000 years from now. However, Mamajek and his collaborators have also demonstrated that the original distance to HIP 85605 was likely underestimated by a factor of ten. At its more likely distance -- about 200 light years -- HIP 85605's newly calculated trajectory would not bring it within the Oort Cloud.

Mamajek worked with former University of Rochester undergraduate Scott Barenfeld (now a graduate student at Caltech) to simulate 10,000 orbits for the star, taking into account the star's position, distance, and velocity, the Milky Way galaxy's gravitational field, and the statistical uncertainties in all of these measurements. Of those 10,000 simulations, 98% of the simulations showed the star passing through the outer Oort cloud, but fortunately only one of the simulations brought the star within the inner Oort cloud, which could trigger so-called "comet showers."

While the close flyby of Scholz's star likely had little impact on the Oort Cloud, Mamajek points out that "other dynamically important Oort Cloud perturbers may be lurking among nearby stars." The recently launched European Space Agency Gaia satellite is expected to map out the distances and measure the velocities of a billion stars. With the Gaia data, astronomers will be able to tell which other stars may have had a close encounter with us in the past or will in the distant future.

Currently, Scholz's star is a small, dim red dwarf in the constellation of Monoceros, about 20 light years away. However, at the closest point in its flyby of the solar system, Scholz's star would have been a 10th magnitude star -- about 50 times fainter than can normally be seen with the naked eye at night. It is magnetically active, however, which can cause stars to "flare" and briefly become thousands of times brighter. So it is possible that Scholz's star may have been visible to the naked eye by our ancestors 70,000 years ago for minutes or hours at a time during rare flaring events.

Read more at Science Daily

Novel crumpling method takes flat graphene from 2-D to 3-D

Researchers at the University of Illinois at Urbana-Champaign have developed a unique single-step process to achieve three-dimensional (3D) texturing of graphene and graphite. Using a commercially available thermally activated shape-memory polymer substrate, this 3D texturing, or "crumpling," allows for increased surface area and opens the doors to expanded capabilities for electronics and biomaterials.

"Fundamentally, intrinsic strains on crumpled graphene could allow modulation of electrical and optical properties of graphene," explained SungWoo Nam, an assistant professor of mechanical science and engineering at Illinois. "We believe that the crumpled graphene surfaces can be used as higher surface area electrodes for battery and supercapacitor applications. As a coating layer, 3D textured/crumpled nano-topographies could allow omniphobic/anti-bacterial surfaces for advanced coating applications."

Graphene--a single atomic layer of sp2-bonded carbon atoms--has been a material of intensive research and interest over recent years. A combination of exceptional mechanical properties, high carrier mobility, thermal conductivity, and chemical inertness, make graphene a prime candidate material for next generation optoelectronic, electromechanical, and biomedical applications.

"In this study, we developed a novel method for controlled crumpling of graphene and graphite via heat-induced contractile deformation of the underlying substrate," explained Michael Cai Wang, a graduate student and first author of the paper, "Heterogeneous, Three-Dimensional Texturing of Graphene," which appeared in the journal Nano Letters. "While graphene intrinsically exhibits tiny ripples in ambient conditions, we created large and tunable crumpled textures in a tailored and scalable fashion."

"As a simpler, more scalable, and spatially selective method, this texturing of graphene and graphite exploits the thermally induced transformation of shape-memory thermoplastics, which has been previously applied to microfluidic device fabrication, metallic film patterning, nanowire assembly, and robotic self-assembly applications," added Nam, whose group has filed a patent for their novel strategy. "The thermoplastic nature of the polymeric substrate also allows for the crumpled graphene morphology to be arbitrarily re-flattened at the same elevated temperature for the crumpling process."

Read more at Science Daily

Humans altering Adriatic ecosystems more than nature, study shows

The ecosystems of the Adriatic Sea have weathered natural climate shifts for 125,000 years, but humans could be rapidly altering this historically stable biodiversity hot spot, a University of Florida study says.

The study details a major shift in bottom-dwelling species in Italy's Po Basin, a region south of Venice known for its ecologically and commercially important shellfish as well as its tourism industry.

"The fossil record suggests that human activities can alter even those ecosystems that have been immune to major changes naturally occurring on our planet," said the study's lead author, Michal Kowalewski, the Thompson Chair of Invertebrate Paleontology at the Florida Museum of Natural History on the UF campus.

"We may be witnessing a permanent shift," Kowalewski said. "This restructuring could have lasting consequences for regional biodiversity, including the overall health of the broader marine ecosystems of the Adriatic."

Mollusks preserve well in the fossil record and tend to be sensitive to human-caused environmental change, making them a good indicator of marine ecosystem health. The study, appearing online this week in the Proceedings of the Royal Society B, documents rapidly changing marine communities in the northern Adriatic, one of Europe's most highly developed industrial and agricultural areas. Researchers tracked changes in shellfish communities by examining a collection of more than 100,000 fossil specimens from geological cores drilled in the region. They then compared the fossil data with surveys of present-day marine ecosystems conducted in the last four decades of the 20th century. The fossil record shows 125,000 years ago the Adriatic region's climate and sea level were similar to today. However, the authors found significant ecosystem changes in the most recent centuries, including a decline in seven out of the 10 historically dominant mollusk species.

The findings echo those of previous studies on Caribbean reef communities.

"The changes found by the study researchers are alarming, but there's reason to believe that other areas have been even more profoundly affected by the effects of pollution, habitat disturbance, lack of oxygen and climate change," said Steven Holland, a University of Georgia paleontologist not involved in the study. "This is a clear fingerprint of the effects of humans."

From Science Daily

Dwarf Planet's Puzzling Landscape Snaps into View

NASA’s Dawn probe is slowly closing in on its final destination and new observations of the dwarf planet Ceres are revealing a fascinatingly complex little world.

“As we slowly approach the stage, our eyes transfixed on Ceres and her planetary dance, we find she has beguiled us but left us none the wiser,” said principal investigator Chris Russell, of the University of California, Los Angeles (UCLA), in a NASA news release. “We expected to be surprised; we did not expect to be this puzzled.”

These most recent images were acquired on Feb. 12 from a distance of around 52,000 miles (83,000 kilometers) as the robotic spacecraft slowly spirals in on its target. In this highest-resolution ever view of Ceres, each pixel represents 4.9 miles (7.8 kilometers).

As opposed to a rapid deceleration burn that would be carried out by spacecraft using conventional rockets for propulsion (in the case of NASA’s Cassini probe, for example), Dawn is taking the slow-yet-steady approach using ion engines. This form of propulsion allows continuous thrust for long periods of time, using tiny quantities of fuel. So rather than flying full-speed at Ceres, Dawn has slowly ‘danced’ into formation around Ceres, allowing us many weeks of a gradually sharpening view as the mission creeps up on the solar system’s innermost dwarf planet.

Of particular interest to planetary scientists remains the bright patches of landscape — including the one particularly bright feature shown in the image above (right frame). Other bright features are present, but the origin of this discrete spot is keeping astrogeologists guessing.

During Dawn’s journey through the asteroid belt — the region of space between the orbits of Mars and Jupiter — the Hubble Space Telescope detected plumes of water around Ceres. Could these plumes be associated with geysers leaking a sub-surface ocean of water into space, as observed at Saturn’s moon Enceladus and Jupiter’s moon Europa? If so, these bright features may highlight venting cracks in Ceres’ crust where water is being forced from the dwarf planet’s interior, venting to space as vapor and freezing on the surface as an icy residue, appearing as bright patches on the cratered surface.

Read more at Discovery News

Link found in how cells start process necessary for life

Researchers have found an RNA structure-based signal that spans billions of years of evolutionary divergence between different types of cells, according to a study led by researchers at the University of Colorado School of Medicine at the Anschutz Medical Campus and published in the journal Nature.

The finding could alter the basic understanding of how two distinct life forms -- bacteria and eukaryotes -- begin the process of protein synthesis.

Jeffrey Kieft, PhD, professor of biochemistry and molecular genetics and corresponding author of the article in Nature, said scientists have long thought that the molecular signals that initiate protein synthesis in bacteria and eukaryotes are mutually exclusive. Scientists in Kieft's lab explored whether a structured RNA molecule from a virus that infects eukaryotic cells could function in bacteria. Surprisingly, they found that it could initiate protein syntheses, a process necessary for life.

"What we found bridges billions of years of evolutionary divergence," said Kieft, who is also a Howard Hughes Medical Institute Early Career Scientist. "We wanted to explore whether it was possible to bypass mechanisms that were specific to each domain of life and find a signal capable of operating in both."

Eukaryotes are organisms, such as plants, animals and fungi, whose cells contain a nucleus and are enclosed within membranes, while prokaryotes, such as bacteria, do not contain a nucleus.

In an article that accompanies the study by Kieft and his colleagues, Eric Jan, associate professor in the Department of Biochemistry and Molecular Biology at the University of British Columbia, calls the finding "surprising" and writes that the CU scientists and their colleagues "have shown for the first time that a bona fide signal in an RNA structure promotes protein synthesis in the two domains of life."

From Science Daily

Ancient rocks show life could have flourished on Earth 3.2 billion years ago

A spark from a lightning bolt, interstellar dust, or a subsea volcano could have triggered the very first life on Earth. But what happened next? Life can exist without oxygen, but without plentiful nitrogen to build genes -- essential to viruses, bacteria and all other organisms -- life on the early Earth would have been scarce.

The ability to use atmospheric nitrogen to support more widespread life was thought to have appeared roughly 2 billion years ago. Now research from the University of Washington looking at some of the planet's oldest rocks finds evidence that 3.2 billion years ago, life was already pulling nitrogen out of the air and converting it into a form that could support larger communities.

"People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn't until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse," said co-author Roger Buick, a UW professor of Earth and space sciences. "Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere."

The results were published Feb. 16 in Nature.

The authors analyzed 52 samples ranging in age from 2.75 to 3.2 billion years old, collected in South Africa and northwestern Australia. These are some of the oldest and best-preserved rocks on the planet. The rocks were formed from sediment deposited on continental margins, so are free of chemical irregularities that would occur near a subsea volcano. They also formed before the atmosphere gained oxygen, roughly 2.3 to 2.4 billion years ago, and so preserve chemical clues that have disappeared in modern rocks.

Even the oldest samples, 3.2 billion years old -- three-quarters of the way back to the birth of the planet -- showed chemical evidence that life was pulling nitrogen out of the air. The ratio of heavier to lighter nitrogen atoms fits the pattern of nitrogen-fixing enzymes contained in single-celled organisms, and does not match any chemical reactions that occur in the absence of life.

"Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating," said lead author Eva Stüeken, who did the work as part of her UW doctoral research. "It suggests that these really complicated enzymes apparently formed really early, so maybe it's not so difficult for these enzymes to evolve."

Genetic analysis of nitrogen-fixing enzymes have placed their origin at between 1.5 and 2.2 billion years ago.

"This is hard evidence that pushes it back a further billion years," Buick said. Fixing nitrogen means breaking a tenacious triple bond that holds nitrogen atoms in pairs in the atmosphere and joining a single nitrogen to a molecule that is easier for living things to use. The chemical signature of the rocks suggests that nitrogen was being broken by an enzyme based on molybdenum, the most common of the three types of nitrogen-fixing enzymes that exist now. Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth -- before the atmosphere contained oxygen to weather rocks -- is more mysterious.

The authors hypothesize that this may be further evidence that some early life may have existed in single-celled layers on land, exhaling small amounts of oxygen that reacted with the rock to release molybdenum to the water.

Read more at Science Daily

Mysterious Mars Plumes Defy Explanation

Amateur astronomers gazing at Mars have discovered gigantic plumes soaring more than 125 miles above the planet’s surface, a phenomenon that so far defies explanation.

At least 18 sightings were reported during two 10-day periods in March and April 2012, when plumes appeared over an area known as Terra Cimmeria, located in Mars’ southern hemisphere.

The plumes extended over 500- to 1,000 kilometers (311- to 621 miles) in both north-south and east-west directions and changed in appearance daily. They were detected as the sun breached Mars’ horizon in the morning, but not when it set in the evening.

“Remarkably ... the features changed rapidly, their shapes going from double blob protrusions to pillars or finger-plume-like morphologies,” scientists investigating the sightings wrote in a paper published in this week’s Nature.

Spacecraft and ground-based telescopes previously had seen clouds made of carbon dioxide and water ice crystals on Mars, but the clouds were typically layered and never rose above 100 kilometers, or 62 miles, from the planet's surface, the researchers noted.

Clouds of dust can be kicked up into the atmosphere during storms, but these max out at about 37 miles in altitude, they added.

The plumes could be some sort of very unusual aurora, 1,000 times brighter than anything seen on Earth, triggered by a very strong magnetic pocket in the planet’s crust that drove solar wind particles out into the atmosphere.

Current understanding of Mars’ atmosphere, however, leaves all explanations wanting.

“Our explanation of this plume as an aurora would require an immense energetic flux, which our calculations show are highly unrealistic,” physicist Agustin Sanchez-Lavega, with the University of the Basque Country in Spain, wrote in an email to Discovery News.

“We favor the cloud scenario -- the condensation of water or carbon dioxide -- since the plume formed in the cold mornings, but we note for this to occur, a large drop in temperature is required at 200 km, something not foreseen by any atmospheric model. Therefore, very particular conditions occurred at that time in the area that currently we do not understand,” he added

The first plume, spotted on March 12, 2012, appeared as a small protrusion in the morning day-night boundary of the Martian southern hemisphere, which was in early winter.

The plume grew over the next several days and between March 20 and March 21 was captured by at least 18 observers using small telescopes.

The phenomenon appeared for a second time over the same area for 10 days between April 6 and April 16, 2012.

“Analysis shows the extreme altitude of the plume top to be above 200 km (124 miles), never before observed on Mars, and reaching the ionosphere and exosphere," the researchers wrote.

More clues may come from NASA’s MAVEN spacecraft, which arrived at Mars in September to study the planet’s atmosphere.

“MAVEN has the ability to see this type of feature very clearly, if it's observing at the right place and the right time,” lead scientist Bruce Jakosky, with the University of Colorado, told Discovery News.

Read more at Discovery News

Penguins Have Bad Taste

There is no such thing as a food connoisseur penguin, suggests new research that found penguins can't taste savory or sweet flavors.

For the flightless, waddling birds, foods come in just two flavors -- salty and sour -- according to the new study, which is published in the latest issue of the journal Current Biology.

“Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don’t have them,” co-author Jianzhi “George” Zhang of the University of Michigan said in a press release. “These findings are surprising and puzzling, and we do not have a good explanation for them. But we have a few ideas.”

Zhang and colleagues made the determination after sequencing the genomes for Adelie and emperor penguins. The researchers were surprised that they couldn’t find some basic taste genes, so they took a closer look at penguin DNA.

This led the scientists to conclude that all penguin species lack functional genes for the receptors of sweet, umami and bitter tastes.

You might think that’s obvious, because penguins aren’t exactly noshing on candy or umami-laden soy sauce. But the reason for the loss likely has more to do with temperature than what the penguins are eating. The clues for this are the missing taste receptors themselves.

Those for sweet, umami and bitter flavors are temperature sensitive. They don’t work well, if at all, if the individual is eating cold food in a cold environment. That’s one reason why people can’t taste the flavors in ice cream very well after a while. The cold dampens their taste buds, as well as ability to smell, a bit.

Penguins or their ancestors probably had all of the usual taste receptors at one point, but lost them when they moved to cold environments. Some penguins have since moved to warmer areas, but because all penguins trace their roots to Antarctica, penguins the world over are still hardwired, taste-wise, for eating in a colder habitat.

Read more at Discovery News

The future of electronics, now in 2-D

The future of electronics could lie in a material from its past, as researchers from The Ohio State University work to turn germanium -- the material of 1940s transistors -- into a potential replacement for silicon.

At the American Association for the Advancement of Science meeting, assistant professor of chemistry Joshua Goldberger reported progress in developing a form of germanium called germanane.

In 2013, Goldberger's lab at Ohio State became the first to succeed at creating one-atom-thick sheet of germanane -- a sheet so thin, it can be thought of as two-dimensional. Since then, he and his team have been tinkering with the atomic bonds across the top and bottom of the sheet, and creating hybrid versions of the material that incorporate other atoms such as tin.

The goal is to make a material that not only transmits electrons 10 times faster than silicon, but is also better at absorbing and emitting light -- a key feature for the advancement of efficient LEDs and lasers.

"We've found that by tuning the nature of these bonds, we can tune the electronic structure of the material. We can increase or decrease the energy it absorbs," Goldberger said. "So potentially we could make a material that traverses the entire electromagnetic spectrum, or absorbs different colors, depending on those bonds."

As they create the various forms of germanane, the researchers are trying to exploit traditional silicon manufacturing methods as much as possible, to make any advancements easily adoptable by industry.

Aside from these traditional semiconductor applications, there have been numerous predictions that a tin version of the material could conduct electricity with 100 percent efficiency at room temperature. The heavier tin atom allows the material to become a 2D "topological insulator," which conducts electricity only at its edges., Goldberger explained. Such a material is predicted to occur only with specific bonds across the top and bottom surface, such as a hydroxide bond.

Read more at Science Daily

Toronto Star Backs Off Anti-Vaccination Story

Last week “The Toronto Star,” one of Canada’s most prestigious newspapers, published an article highlighting the dangers of the Gardasil anti-HPV vaccine. The article, by David Bruser and Jesse McLean, told the stories of a dozen Canadian girls whose health failed after receiving the vaccine and suggested that it was dangerous.

Though the reporters acknowledged that “Health Canada and the U.S. FDA say the vaccine is safe. Hundreds of thousands of teenage girls in Canada have received the vaccine’s three doses, the vast majority without incident,” these caveats were largely overshadowed by dramatic and moving accounts of injured girls and ruined lives.

A few years ago such a story might have been ignored, but amid the current climate of vaccination concerns it provoked a firestorm of criticism from doctors and public health officials who claimed it was misleading and would fuel anti-vaccination fears.

The Star dug itself deeper when its columnist Heather Mallick defended the original reporting while acknowledging that “I’ve been trying to teach myself about statistics and science.”

“I’m reading doctor and science writer Ben Goldacre’s new book, ‘I Think You’ll Find It’s a Bit More Complicated Than That,’ about the widespread misunderstanding of research and results,” Mallick said.

Goldacre, a longtime, staunch proponent of vaccination, was alarmed that his name had been invoked in defense of anti-vaccination reporting and took to Twitter to admonish both Mallick and “The Star.”

After doubling down for nearly a week The Star acknowledged that they “failed” in their reporting and did not give proper weight to science. According to a story by Global News Canada:

“The Star’s publisher John Cruickshank said the paper failed the public in the way it presented its story…. Cruickshank took responsibility for the way the story was presented and said he understands why it could have given readers the false impression that Gardasil is dangerous.”

That same day the newspaper published an op-ed endorsed by 63 doctors and public health specialists that stated in part:

Although the article states in the fifth paragraph that “there is no conclusive evidence showing the vaccine caused a death or illness,” its litany of horror stories and its innuendo give the incorrect impression that the vaccine caused the harm. Very unfortunately, this article may well lead readers to doubt both the scientific evidence and the recommendations of the Public Health Agency of Canada, the Society of Obstetricians and Gynecologists of Canada, the National Advisory Committee on Immunization, and the Canadian Cancer Society about vaccination…. The Star presented the stories of women who have suffered greatly. The article was engaging, dramatic and might have created fear. But study after study has shown that there is no causal link between the events the Star reported and the vaccine. About 169 million doses of the HPV vaccine have been administered worldwide. In any given large population, there will be illness and death.

This sort of story is not unusual. Last year dozens of Colombian teens complained about strange symptoms including headaches, convulsions and fainting in the days and weeks after many of them got a HPV vaccination.

Read more at Discovery News