Kepler's 'Alien Megastructure' Star Just Got Weirder

You're probably all too familiar with the story of KIC 8462852, a star that's been the focus of much speculation and excitement over the past few months.

KIC 8462852 was observed by NASA's Kepler mission and has become infamous for its bizarre and unprecedented transit signal that was flagged by citizen scientists. Now new research of precision Kepler observations has shown that the overall brightness of the star -- unofficially named "Tabby's Star" after astronomer Tabetha S. Boyajian who discovered the peculiar signal -- has been decreasing, which poses a new and confusing problem for astronomers trying to understand what the heck is going on.

Kepler's prime mission is to look for small worlds that pass in front of their parent stars causing a slight dimming of starlight. The "transit method" has been hugely successful and has confirmed well over 2,000 planets orbiting other stars in our galaxy.

But Tabby's Star's transit signal, otherwise known as a "light-curve", stopped astronomers in their tracks. Something passed in front of it, dimming its starlight a whopping 20 percent and other jumbled transit signals revealed that something wasn't quite right with this particular star. Then, in an interview with The Atlantic, Penn State University astronomer Jason Wright speculated that the signal could be indicative of an "alien megastructure" that's in the process of being built. You can catch up on the controversy surrounding the anomalous signal in my recent Discovery News article "Closing In on 'Alien Megastructure' Clues."

So, until now the leading (natural) explanation of the strange light-curve has focused on the possibility of a huge swarm of comets passing in front of the star, blocking a substantial portion of starlight from Kepler's optics. Recently, this hypothesis was given a little more credence after observations by the Submillimeter Array and the James Clerk Maxwell Telescope in Hawaii revealed little evidence it might be caused by the debris cloud of some planetary spashup. But the "swarm of comets" explanation still fell short of fully explaining the phenomenon, though for now it remains the leading rationale.

All this uncertainty has only boosted speculation surrounding the (unnatural) explanation: that an advanced alien civilization is building some kind of Dyson Sphere-like structure around a star to (perhaps) collect solar energy for all their energy consumption needs. In this scenario, pieces of the alien array are passing in front of the star, causing the anomalous transit signal. Of course, scientists being a rational bunch think there's a more likely explanation for the light-curve, but aliens always seem to hog headlines.

So, in an effort to track down a rational explanation, Bradley Schaefer from Louisiana State University decided to study historical observations of KIC 8462852 in astronomical photographic plates from the past century to see if the star exhibited any bizarre fluctuations in brightness in the past. Sure enough, yes, the star is a bit of an oddball and has shown a long-term decreasing trend in brightness! Since the 19th Century, its brightness has decreased steadily by nearly 20 percent.

Now, astronomers Ben Montet (from Caltech) and Joshua Simon (from the Carnegie Institute) have released a paper to the arXiv preprint service detailing recent Kepler observations of KIC 8462852 since the space telescope was launched in 2009. Although the dataset for this time period is comparatively small, Monet and Simon found yet another surprise.

In the 4 years of Kepler's primary mission, the star showed an unprecedented dimming of 3.5 percent. So not only did Kepler detect transient dips in brightness of up to 20 percent, there also seems to be a very definite downward trend in brightness throughout our observational history of the star.

No matter how you slice it, this is strange.

After studying photometric observations for other stars surrounding KIC 8462852, there's no other star that shows such dramatic behavior. What's more, there's very few known phenomena that could be causing this. So once again, astronomers are clutching at straws in an effort to explain what is going on.

"Broadly speaking, the morphology of the light curve is generally consistent with the transit of a cloud of optically thick material orbiting the star," Monet and Simon write in their paper. "The breakup of a small body or a recent collision that could produce a cloud of material could also plausibly produce a family of comets that transit the host star together as one group, explaining the light curve..."

Read more at Discovery News

New 'Echo Hunter' Whale Species Had Ultrasonic Hearing

Sound is produced by Echovenator sandersi, which bounces off prey to create echoes. This illustration shows how these echoes are detected via conduction of vibrations through the mandible and received by the whale's inner ear.

A new whale species with the name "Echo Hunter" (Echovenator sandersi), for its super-hearing, has just been described, and it's helping researchers gain new insight into the evolution of high-frequency hearing in the the earliest whales.

The finding comes thanks to a fossil, dated to 27 million years ago, that includes a highly-intact skull. It was examined by researchers from the New York Institute of Technology (NYIT), who got the chance to study what they say is one of the most well preserved fossils ever found of a whale's ear.

And what an ear. Aided by uniquely shaped inner ear structures, the whale could hear sounds far outside the range of human ears.

"This was a small, toothed whale that probably used its remarkable sense of hearing to find and pursue fish, with echoes only," explained study co-author Jonathan Geisler, an NYIT associate professor, in a statement.

High-frequency hearing capability is a necessary feature of all toothed whales, which use it in conjunction with echoes of their own calls in order to echolocate – using sound to map out their surroundings and navigate and seek food. Bats use it. So do dolphins.

"This would allow it to hunt at night," said Geisler. "But, more importantly, it could hunt at great depths in darkness, or in very sediment-choked environments."

The NYIT researchers say their study shows that most of the features for high-frequency hearing in the animals were in place 27 million years ago, around the same time that echolocation evolved. Some features might have even evolved earlier than that.

"Previous studies have looked at hearing in whales but our study incorporates data from an animal with a very complete skull," said postdoctoral fellow Morgan Churchill, the lead author of the study.

"The data we gathered enabled us to conclude that it could hear at very high frequencies," he noted, "and we can also say with a great degree of certainty where it fits in the tree of life for whales."

Detailed findings about the new species and its hearing have been published in the journal Current Biology.

From Discovery News

Veins on Mars were formed by evaporating ancient lakes

Drill hole into the John Klein target within Sheepbed Member of Yellowknife Bay, with a light-toned sulfate veinlet visible on the back wall. The light-toned veins have been identified as sulfates by ChemCam (Nachon et al.; Schroeder et al.) and CheMin (Vaniman et al.). Drill hole is 1.6 cm diameter. Image is white balanced. Scale bar is 2 cm.

Mineral veins found in Mars's Gale Crater were formed by the evaporation of ancient Martian lakes, a new study has shown.

The research, by Mars Science Laboratory Participating Scientists at The Open University and the University of Leicester, used the Mars Curiosity rover to explore Yellowknife Bay in Gale Crater on Mars, examining the mineralogy of veins that were paths for groundwater in mudstones.

The study suggests that the veins formed as the sediments from the ancient lake were buried, heated to about 50 degrees Celsius and corroded.

Professor John Bridges from the University of Leicester Department of Physics and Astronomy said: "The taste of this Martian groundwater would be rather unpleasant, with about 20 times the content of sulphate and sodium than bottled mineral water for instance!

"However as Dr Schwenzer from The Open University concludes, some microbes on Earth do like sulphur and iron rich fluids, because they can use those two elements to gain energy. Therefore, for the question of habitability at Gale Crater the taste of the water is very exciting news."

The researchers suggest that evaporation of ancient lakes in the Yellowknife Bay would have led to the formation of silica and sulphate-rich deposits.

Subsequent dissolution by groundwater of these deposits -- which the team predict are present in the Gale Crater sedimentary succession -- led to the formation of pure sulphate veins within the Yellowknife Bay mudstone.

The study predicts the original precipitate was likely gypsum, which dehydrated during the lake's burial.

The team compared the Gale Crater waters with fluids modelled for Martian meteorites shergottites, nakhlites and the ancient meteorite ALH 84001, as well as rocks analysed by the Mars Exploration rovers and with terrestrial ground and surface waters.

The aqueous solution present during sediment alteration associated with mineral vein formation at Gale Crater was found to be high in sodium, potassium and silicon, but had low magnesium, iron and aluminium concentrations and had a near neutral to alkaline pH level.

The mudstones with sulphate veins in the Gale Crater were also found to be close in composition to rocks in Watchet Bay in North Devon, highlighting a terrestrial analogue which supports the model of dissolution of a mixed silica and sulphate-rich shallow horizon to form pure sulphate veins.

Read more at Science Daily

Do black holes have a back door?

An artist's drawing a black hole named Cygnus X-1. It formed when a large star caved in. This black hole pulls matter from blue star beside it.

One of the biggest problems when studying black holes is that the laws of physics as we know them cease to apply in their deepest regions. Large quantities of matter and energy concentrate in an infinitely small space, the gravitational singularity, where space-time curves towards infinity and all matter is destroyed. Or is it? A recent study by researchers at the Institute of of Corpuscular Physics (IFIC, CSIC-UV) in Valencia suggests that matter might in fact survive its foray into these space objects and come out the other side.

Published in the journal Classical and Quantum Gravity, the Valencian physicists propose considering the singularity as if it were an imperfection in the geometric structure of space-time. And by doing so they resolve the problem of the infinite, space-deforming gravitational pull.

"Black holes are a theoretical laboratory for trying out new ideas about gravity," says Gonzalo Olmo, a Ramón y Cajal grant researcher at the Universitat de València (University of Valencia, UV). Alongside Diego Rubiera, from the University of Lisbon, and Antonio Sánchez, PhD student also at the UV, Olmo's research sees him analysing black holes using theories besides general relativity (GR).

Specifically, in this work he has applied geometric structures similar to those of a crystal or graphene layer, not typically used to describe black holes, since these geometries better match what happens inside a black hole: "Just as crystals have imperfections in their microscopic structure, the central region of a black hole can be interpreted as an anomaly in space-time, which requires new geometric elements in order to be able to describe them more precisely. We explored all possible options, taking inspiration from facts observed in nature."

Using these new geometries, the researchers obtained a description of black holes whereby the centre point becomes a very small spherical surface. This surface is interpreted as the existence of a wormhole within the black hole. "Our theory naturally resolves several problems in the interpretation of electrically-charged black holes," Olmo explains. "In the first instance we resolve the problem of the singularity, since there is a door at the centre of the black hole, the wormhole, through which space and time can continue."

This study is based on one of the simplest known types of black hole, rotationless and electrically-charged. The wormhole predicted by the equations is smaller than an atomic nucleus, but gets bigger the bigger the charge stored in the black hole. So, a hypothetical traveller entering a black hole of this kind would be stretched to the extreme, or "spaghettified," and would be able to enter the wormhole. Upon exiting they would be compacted back to their normal size.

Seen from outside, these forces of stretching and compaction would seem infinite, but the traveller himself, living it first-hand, would experience only extremely intense, and not infinite, forces. It is unlikely that the star of Interstellar would survive a journey like this, but the model proposed by IFIC researchers posits that matter would not be lost inside the singularity, but rather would be expelled out the other side through the wormhole at its centre to another region of the universe.

Another problem that this interpretation resolves, according to Olmo, is the need to use exotic energy sources to generate wormholes. In Einstein's theory of gravity, these "doors" only appear in the presence of matter with unusual properties (a negative energy pressure or density), something which has never been observed. "In our theory, the wormhole appears out of ordinary matter and energy, such as an electric field" (Olmo).

Read more at Science Daily

Scientists discover light could exist in a previously unknown form

Artistic image of light trapped on the surface of a nanoparticle topological insulator.

New research suggests that it is possible to create a new form of light by binding light to a single electron, combining the properties of both.

According to the scientists behind the study, from Imperial College London, the coupled light and electron would have properties that could lead to circuits that work with packages of light -- photons -- instead of electrons.

It would also allow researchers to study quantum physical phenomena, which govern particles smaller than atoms, on a visible scale.

In normal materials, light interacts with a whole host of electrons present on the surface and within the material. But by using theoretical physics to model the behaviour of light and a recently-discovered class of materials known as topological insulators, Imperial researchers have found that it could interact with just one electron on the surface.

This would create a coupling that merges some of the properties of the light and the electron. Normally, light travels in a straight line, but when bound to the electron it would instead follow its path, tracing the surface of the material.

In the study, published today in Nature Communications, Dr Vincenzo Giannini and colleagues modelled this interaction around a nanoparticle -- a small sphere below 0.00000001 metres in diameter -- made of a topological insulator.

Their models showed that as well as the light taking the property of the electron and circulating the particle, the electron would also take on some of the properties of the light.

Normally, as electrons are travelling along materials, such as electrical circuits, they will stop when faced with a defect. However, Dr Giannini's team discovered that even if there were imperfections in the surface of the nanoparticle, the electron would still be able to travel onwards with the aid of the light.

If this could be adapted into photonic circuits, they would be more robust and less vulnerable to disruption and physical imperfections.

Dr Giannini said: "The results of this research will have a huge impact on the way we conceive light. Topological insulators were only discovered in the last decade, but are already providing us with new phenomena to study and new ways to explore important concepts in physics."

Dr Giannini added that it should be possible to observe the phenomena he has modelled in experiments using current technology, and the team is working with experimental physicists to make this a reality.

Read more at Science Daily

Macaques Grin in Sleep, Push Back Origin of Smiles

Baby macaques have been caught smiling for no good reason, even in their sleep, which means monkeys can join the small club of documented so-called "spontaneous smilers."

That's according to a new study from Kyoto University's Primate Research Institute, where researchers observed several dozen smiles from seven macaque newborns.

Spontaneous smiles in infants – facial movements that frequently happen during sleep and have no discernible cause, internally or externally – have, of course, been seen in humans and also, more recently, in chimpanzees.

"About a decade ago we found that chimp infants also display spontaneous smiles," said study co-author Masaki Tomonaga in a statement. "Since we see the same behavior in more distant relatives, we can infer that the origin of smiles goes back at least 30 million years, when old world monkeys and our direct ancestors diverged."

The study's lead author, Fumito Kawakami, noticed macaque newborns smiling during health exams, and that prompted a closer look at the behavior, culminating in a study just published in the journal Primates.

As can be seen in the video, the word "smiling" is used broadly, when compared with the everyday impression of what constitutes, say, a human smile.

"Spontaneous macaque smiles are more like short, lop-sided spasms compared to those of human infants," explained Kawakami.

Read more at Discovery News

Lasers melt rocks to reveal development of super-Earths and how giant impacts make magma

High-powered lasers melt mineral for planet formation experiments. Researchers observed the melting of forsterite, the most common constituent of Earth's mantle, to understand how the cores of planets form and develop. The laser is able to create pressures representative of the extreme collisions between objects in space. The target is a 4 millimeter square. Al is aluminum and Qz is quartz. Image by Toshimori Sekine, Hiroshima University. Image may only be re-used with attribution.

New experiments provide insight into how Earth-type planets form when giant asteroids or planetesimals collide and how the interiors of such planets develop. Researchers at Hiroshima University, Osaka University, Ehime University, University of Tokyo, and the Chiba Institute of Technology collaborated to publish their research in the August 3, 2016 issue of Science Advances.

"Our results provide a better understanding how impact-generated magmas evolve and allow us to model Earth-type planets' inner structures. Collisions at these extreme temperatures and pressures created our own Earth and may have also formed the mantles of other Super Earth planets, for example CoRoT-7b and Kepler-10b," said Toshimori Sekine, Ph.D., first author of the research paper and Professor at Hiroshima University.

These powerful collisions cause chemical reactions within the giant rocks and knowing what types of reactions occur under what conditions gives researchers a better understanding of the development of planets too far away for satellites to explore. Many of the rocks include forsterite, a representative mineral that makes up much of the matter in space. Forsterite, known to scientists as Mg2SiO4, is a combination of Magnesium, Silicone, and Oxygen and is the most abundant constituent of Earth's mantle, the layer between the surface crust and molten core.

The research team of geophysicists and engineers successfully measured the melting of forsterite. However, replicating the intense collisions that can turn minerals into magma in Earth-based experiments was a challenge.

"The laser shock technique was first used in the 1990s, but the results were not precise. Recent technical advances enable us to measure precisely the laser-shocked states," said Sekine.

The laser shock technique uses a high-power laser to irradiate a target, which was a block of forsterite in the experiments by Sekine's team. The energy of the irradiation causes an abrupt expansion of the target's molecules and the inertia of this expansion generates a shock wave. The energy from the shock wave can create heat and light that melts and reflects off of the forsterite.

Previous studies without the laser shock technique only measured the properties of forsterite at shock pressures below 200 Giga Pascals (GPa). The new experiments put forsterite crystals under pressures between approximately 250 and 970 GPa. For comparison, the pressure at the center of Earth is estimated to be 360 GPa.

Researchers measured the pressure, temperature, density, and reflectivity of laser-shocked forsterite. These parameters did not increase at a constant rate as the pressure steadily increased, revealing that both energy producing and energy absorbing reactions occur in shocked forsterite melt at pressures between 250 GPa and 344 GPa.

Earlier research has connected magnesium oxide, one of the minerals that is formed from forsterite, to the reactions necessary for a planet to develop a magnetic field that persists for a long geological time, such as the magnetic field of Earth. With these new details of forsterite's melting behavior, researchers may be able to predict how minerals separate into different layers of magma and which minerals may be close enough to react.

Read more at Science Daily

Evidence for China's Great Flood Found

Researchers have found the first evidence for the legendary Great Flood on the Yellow River, a massive, catastrophic event that occurred about 4,000 years ago and ultimately produced the first dynasty of China.

Folk traditions and written records recount how the hero Yu dredged and tamed the destructive floodwaters about 4,000 years ago.

Yu's decades-long feat earned him "the divine mandate to establish the Xia dynasty, the first in Chinese history, and marked the beginning of Chinese civilization," Qinglong Wu, a researcher at Peking University and Nanjing Normal University, China, and colleagues wrote in Science.

Until now no direct evidence of the cataclysm had been discovered.

"In the absence of geological evidence for such a flood, some scholars have argued that the story is either a historicized version of an older myth or propaganda to justify the centralized power of imperial rule," David Montgomery, professor of Earth and Space Sciences at the University of Washington in Seattle, wrote in a related Science paper.

Mapping distinctive sediments that are widely distributed along the Yellow River valley, Wu and colleagues were able to reconstruct the sequence of events that led to the flood. The sediments included deposits sourced from the gorge upstream.

"They are the direct and solid evidence of a great flood. Only a large flood can deposits such sediments," Wu told Discovery News.

According to the researchers, it all began with an earthquake which destroyed the Lajia site, a settlement of the Qijia culture, which is famous for having produced the world's earliest noodles.

Cave dwellings at Lajia collapsed, killing all the people there.

But the quake was even more destructive. It triggered a massive rock slide that dammed the river and backed up a lake.

"The lake was at least 200 meters (approx. 650 feet) deep," Purdue University professor Darryl Granger said.

Within six to nine months, the lake overflowed and the landslide dam failed catastrophically, sweeping over the Lajia site.

The researchers were able to determine the dimension of the flood channel and exactly how high the flood waters reached.

"The evidence found in our investigations along the Yellow River in Qinghai Province includes remains of a landslide dam, dammed lake sediments upstream, and outburst flood sediments downstream that allow us to reconstruct the size of the lake and flood," the researchers wrote.

The ancient landslide dam deposits reach an elevation of 785 feet above the present river level and stretch for more than 4,200 feet along Jishi Gorge.

Overall, the flood that broke the dam was of enormous proportions.

"It was about 300-500,000 cubic meters per second. To put that into perspective, it is among the largest known floods to have happened on Earth during the past 10,000 years," Granger said.

Using radiocarbon dating techniques on samples that included the skeletons of children who died in the earthquake at Lajia, the researchers dated the flood to 1920 B.C.

Read more at Discovery News

Sunflowers Sway to Summer's Rhythms

Mature sunflowers are remarkable for their uniform eastward orientation.

Young sunflowers do what looks like a slow dance each day, turning and swaying of their own apparent volition, and now new research finds that these moves are driven by the sun, plant hormones and the sunflowers' internal clock.

This behavior of sunflowers was noticed way back in 1898, but the new study -- published in the journal Science -- is the first to explain in detail why it happens. The study is also the first to show that internal clock regulation of growth promotes overall plant yield, which in this case can lead to hefty, leafy tall sunflowers.

A field of sunflowers in Lopburi, Thailand.

The findings add to growing evidence that plants are more animal-like than most of us might think.

"Plants are exquisitely sensitive to the environment -- that is how they survive while stuck in one place -- and have senses very analogous to all the human senses," senior author Stacey Harmer, a professor in the University of California at Davis' Department of Plant Biology, told Discovery News. "For me, the big difference is the time scale of many of the responses."

"Plants actually have color vision," she continued. "They have several families of photoreceptors that allow them to see many different wavelengths of light: UV, blue, green, red, far-red … . Note that plants can see wavelengths of light that humans can't detect (UV and far-red). They use these photoreceptors, in particular, those that are sensitive to blue light, to track the sun."

Growing sunflowers "watch" the sun and move with it, beginning their days with their heads facing east, swinging west throughout the day, and turning back to the east at night.

For the study, funded by the National Science Foundation's Plant Genome Research Program, Harmer and postdocs Hagop Atamian and Nicky Creux joined forces with scientist Benjamin Blackman and his lab members Evan Brown and Austin Garner.

Atamian, collaborating with other members of the team, carried out a series of experiments on sunflowers in the field, in pots outdoors and in indoor growth chambers.

By staking plants so that they could not move, or turning potted plants around daily so that they were facing the wrong way, Atamian showed that he could disrupt their ability to track the sun. He also noticed that sunflowers prevented from moving were not as bulky and leafy as those that were free to move.

A sunflower just prior to bud opening.

When plants were moved into an indoor growth chamber with an immobile overhead light, they continued to swing back and forth for a few days, which Harmer said is what would be expected when behavior is driven by an internal clock.

The indoor plants did start tracking the "sun" again when the apparent source of lighting was moved across the growth chamber by turning adjacent lights on and off during the day. The plants could reliably track the movement and return at night when the artificial day was close to a 24-hour cycle, but not when it was closer to 30 hours.

Next, Atamian put ink dots on some sunflower stems and filmed them. Using time-lapse video, he measured the changing distance between the dots and determined that when sunflowers track the sun, the east sides of their stems grew more rapidly than the west sides. At night, the west sides grew faster as the stem swung the other way.

Harmer explained that, as a result, "the back and forth rhythmic growth of sunflowers is due to asymmetrical growth on the opposite sides of the stem."

Read more at Discovery News

Teeny Radar Antenna Tracks the Flight of the Bumblebee

For the first time, scientists have tracked the flight paths of bumblebees over the span of their entire lives.

Not only do the results help biologists better understand bee behavior, but because the insects play a critical role in pollinating crops, understanding their movements could improve how farmers manage agriculture.

Joseph Woodgate of Queen Mary University of London and his colleagues used radar to monitor the daily flight patterns of four different bees, from the time they first left their nests to the time they ceased to return.

Because only one bee could be tracked at a time with the radar, the researchers set out four different colonies at four different times, tracking one bee each time.

"For the first time, we have been able to record the complete 'life story' of a bee," study coordinator Lars Chittka said in a press release. "From the first time she saw the light of day, entirely naive to the world around her, to being a seasoned veteran forager in an environment full of sweet nectar rewards and dangerous threats, to her likely death at the hands of predators, or getting lost because she has ventured too far from her native nest."

To monitor the insects, the scientists affixed a radar transponder just 16 millimeters tall to each bee using superglue. The antenna didn't harm the bee or interfere with its normal activities as it spent its days foraging a field of wild flowers and thistle in Hertfordshire, UK.

From those four bees, the scientists gathered data from 244 flights, adding up to 15,000 minutes of flight and covering 111 miles.

Previous studies had shown that foraging bumblebees tended to explore the area looking for food or exploit it, settling down to harvest. But how long they explored vs exploited was unknown.

"One of the most striking results to emerge," the researchers say in their paper published today in the journal PLOS ONE, "is the large degree to which our bees differed from one another."

All the flights undertaken by four different bees (panels A, B, C, and D) throughout their lives. Green indicates exploratory paths; blue shows looping flights close to the nest; yellow and orange show the bees exploiting good forage.

For example, Bee 1 spent a much higher proportion of her time exploiting -- more than 90 percent. But Bees 2 and 3 spent more time exploring. Bees 1 and 3 didn't travel as far as 2 and 4 in their explorations. Bees 1 and 4 switched the destination of their flights over the course of their foraging and never returned to the first location they foraged.

Read more at Discovery News