Jun 27, 2015
X-ray observations of nearby galaxies have revealed these exceptionally luminous sources at off-nuclear positions that radiate about million times higher power than the Sun. The origins of ULXs have been a subject of heated debate for a long time. The basic idea is that a ULX is a close binary system consisting of a black hole and a star. As matter from the star falls onto the black hole, an accretion disk forms around the black hole. As the gravitational energy of the material is released, the innermost part of the disk is heated up to a temperature higher than 10 million degrees, which causes it to emit strong X-rays.
The unsolved key question about these objects asks: what is the mass of the black hole in these bright objects? ULXs are typically more than a hundred times more luminous than known black hole binaries in the Milky Way, whose black hole masses are at most 20 times the mass of the Sun.
There are two different black hole scenarios proposed to explain these objects: (1) they contain very "big" black holes that could be more than a thousand times more massive than the Sun (Note 1), or (2) they are relatively small black holes, "little monsters" with masses no more than a hundred times that of the Sun, that shine at luminosities exceeding theoretical limits for standard accretion (called "supercritical (or super-Eddington) accretion," Note 2). Such supercritical accretion is expected to produce powerful outflow in a form of a dense disk wind.
To understand which scenario explains the observed ULXs researchers observed four objects: Holmberg II X-1, Holmberg IX X-1, NGC 4559 X-7, NGC 5204 X-1, and took high-quality spectra with the FOCAS instrument on Subaru Telescope for four nights. The image shows an optical multi-color image toward Holmberg II X-1 as observed with Hubble Space Telescope. The object X-1, indicated by the arrow, is surrounded by a nebula (colored in red), which is most likely the gas heated by strong radiation from the ULX.
The team discovered a prominent feature in the optical spectra of all the ULXs observed. It is a broad emission line from helium ions, which indicates the presence of gas heated to temperatures of several tens of thousands of degrees in the system. In addition, they found that the width of the hydrogen line, which is emitted from cooler gas (with a temperature of about 10,000 K), is broader than the helium line. The width of a spectral line reflects velocity dispersion of the gas and shows up due to the Doppler effect caused by a distribution of the velocities of gas molecules. These findings suggest that the gas must be accelerated outward as a wind from either the disk or the companion star and that it is cooling down as it escapes.
Distant ULXs and a Similar Mysterious Object in the Milky Way
The activity of these ULXs in distant galaxies is very similar to a mysterious object in our own Milky Way. The team noticed that the same line features are also observed at SS 433, a close binary consisting of an A-type star and most probably a black hole with a mass less than 10 times that of the Sun. SS 433 is famous for its persistent jets with a velocity of 0.26 times the speed of light. It is the only confirmed system that shows supercritical accretion (that is, an excessive amount of accretion that results in a very powerful outflow). By contrast, such features have not been observed from "normal" black hole X-ray binaries in the Milky Way where sub-critical accretion takes place.
After carefully examining several possibilities, the team concluded that huge amounts of gas are rapidly falling onto "little monster" black holes in each of these ULXs, which produces a dense disk wind flowing away from the supercritical accretion disk. They suggest that "bona-fide" ULXs with luminosities of about million times that of the Sun must belong to a homogeneous class of objects, and SS 433 is an extreme case of the same population. In these, even though the black hole is small, very luminous X-ray radiation is emitted as the surrounding gas falls onto the disk at a huge rate.
If the system is observed from a vertical direction, it's clear that the central part of the accretion disk emits intense X-rays. If SS 433 were observed in the same direction, it would be recognized as the brightest X-ray source in the Milky Way. In reality, since we are looking at SS 433 almost along the disk plane, our line-of-sight view towards the inner disk is blocked by the outer disk. The accretion rate is inferred to be much larger in SS 433 than in the ULXs, which could explain the presence of persistent jets in SS 433.
Read more at Science Daily
Associate Professor Steve Chenoweth from The University of Queensland's School of Biological Sciences said the study showed that male harassment of females hampered the species' ability to adapt to new environmental conditions.
"We found that sexually attractive females were overwhelmed by male suitors," he said.
"Female fruit flies with superior genes that allow them to lay more eggs were so attractive to male suitors they spent most of the time fending off male suitors rather than actually laying eggs.
"The end result was that these supposedly 'superior' genes could not be passed on to the next generation."
The genetic study found a large number of genes appeared to be a double-edged sword for females.
The genes increased their egg-laying ability but with the unfortunate side effect of boosting sexual attractiveness to a level where males wouldn't leave them alone.
The researchers allowed different groups of flies to adapt to a new environment in the lab for 13 generations.
They manipulated the number of potential mates that males and females had in each group, thereby controlling the potential harassment rate.
At the end of the experiment, researchers sequenced the genomes of the flies and found a number of genes that became more common when harassment was not allowed, but these same genes became rare when male harassment was allowed to occur as usual.
As such, increased male attention held the population back and stopped the flies from adapting as well as they could.
Associate Professor Chenoweth said the study's results were significant.
"We have known for some time of these harmful interactions between males and females," he said.
"However, we hadn't realised there may be a large number of genes fueling the interactions, or that these types of genes hamper a species' ability to adapt to new conditions."
Associate Professor Chenoweth heads a laboratory in UQ that uses new genomic technology to answer questions of evolutionary behaviour.
He said future directions for the study included pinpointing the exact types of gene functions involved and to understanding the broader consequences of male-female interactions and their relevance to the evolutionary history of other species.
From Science Daily
Jun 26, 2015
If the proposed changes, outlined in the latest issue of Science Advances, are implemented, the world’s tigers would only fall into two subspecies: the Sunda tiger and the continental tiger. These subspecies would no longer be recognized: Bengal tiger, Caspian tiger, Amur tiger, Javan tiger, South Chinese tiger, Balinese tiger, Sumatran tiger, Indochinese tiger, and Malayan tiger.
“A classification into too many subspecies — with weak or even no scientific support — reduces the scope of action for breeding and rehabilitation programs,” lead author Andreas Wilting told Discovery News. “For example, tiger populations in South China and Indochina have been reduced to such low numbers that, if each continues to be classified as separate subspecies, they would likely face extinction.”
By combining these and other “continental” tigers into one subspecies, he argues they can be “managed as a single conservation unit.”
The situation is dire, as fewer than 4000 tigers inhabit the forests of Asia. The big cats occupy only 7 percent of their estimated former distribution range. Habitat loss and degradation, as well as hunting by humans, are the primary threats to tigers now.
Wilting explained, “There is still a very high demand for various products from wild tigers, particularly in Eastern Asia.”
For the study, Wilting and an international team of researchers compared the form and structure of more than 200 tiger skulls as well as the coloration and stripe patterns of more than 100 tiger skins with molecular genetic data, ecological and life history traits.
The comparisons found that there is tremendous overlap between the existing nine subspecies. Tigers from the three Sunda islands — Sumatra, Java and Bali — were, however, different enough from continental tigers to warrant their classification into a separate subspecies.
Right now subspecies are largely defined by a population’s primary geographic region, which is why their locations are in their subspecies names, from Bengal to Malayan.
“The problem with using the geographical distribution is that it is arbitrary where to draw the lines, particularly on continuous habitats such as continental Asia,” Wilting said, explaining that no clear geographical barriers have existed over the past ten thousand or more years for mainland Asian tigers.
The taxonomic status of all living wild cats is now being revised by a working group of the IUCN/SSC Cat Specialist Group. The co-chairs of that are Urs Breitenmoser and his wife Christine Breitenmoser-Würsten.
While the Breitenmosers suggest that more research is needed on tigers before a decision is made on the proposed changing of subspecies, they told Discovery News that “the practical consequences for conservation could be that the reduction of subspecies in tigers could considerably ease translocation and therefore the recolonization.”
They explained that re-introducing tigers into their known native habitats is just one of many conservation tools that are being considered.
Read more at Discovery News
Shabani, an 18-year-old silverback who tips the scales at around 180 kilograms (400 pounds), has become the star attraction at Higashiyama Zoo and Botanical Gardens in Nagoya, striking smouldering poses the movie model in ”Zoolander” would be proud of.
“He often rests his chin on his hands and looks intently at you,” zoo spokesman Takayuki Ishikawa told AFP on Friday.
“He is more buff than most gorillas and he’s at his peak physically. We’ve seen a rise in the number of female visitors — women say he’s very good-looking.”
Shabani, who has been at the zoo since 2007, shot to fame after being made the campaign model for the zoo’s spring festival earlier this year, Ishikawa said, adding that the ape’s paternal skills are also a big hit with women.
“He’s a father and he always protects and looks over his children,” he said. “Zoo-goers think his kindness is attractive too.”
Women have taken to social media to swoon about Shabani’s rugged looks, describing him as “ikemen” — or a hunk — and likening him to a male model.
Read more at Discovery News
The vessel is known with the name “funnel beaker,” a kind of ceramics which features a flat bottom with a funnel shaped neck. Such earthenware is characteristic of the Funnel Beaker Culture (4000 – 2800 B.C.), which represents the first farmers in Scandinavia and the north European plain.
It was found in pieces in a former fjord east of Rødby Havn, on the south coast of Lolland, Denmark.
“It is one of three beakers at the site, which originally was deposited whole probably containing some food or liquid presumably as part of some long forgotten ritual,” Line Marie Olesen, archaeologist at the Museum Lolland-Falster, told Discovery News.
At the same site Olesen and colleagues last year found a 5,500-year-old flint axe with the handle still attached. The axe was deliberately jammed into what used to be the seabed during the Stone Age.
As the beaker was brought to the Danish National Museum for conservation, experts noticed a fingerprint on the interior surface.
“It must have been left there while manufacturing the pot,” Olesen said.
According to Olesen, a lot of time and symbolism was put into the manufacture and decoration of the funnel beakers and associated pots.
“From the contexts in which they appear it is obvious that they played an important part in everyday life, be it ritual or profane,” she added.
“The fragile fingerprint, left unintentionally, is an anonymous, yet very personal signature, which somehow brings us a bit closer to the prehistoric people and their actions,” Olesen said.
Last year the same archaeological survey unearthed 5,000-year-old footprints left by people who attempted to save parts of their fishing system before it was flooded and covered in sand.
“An unknown persons gallery is gradually developing before our eyes, of the people who lived by Lolland’s southern coast at the time when agriculture was introduced some 6,000 years ago,” Anne-Lotte Sjørup Mathiesen of the Museum Lolland-Falster, said in a statement.
Read more at Discovery News
|A tortoise beetle and her poo-tipped brood doing the most disgusting impression of a Bloomin' Onion ever.|
Aside from being a bit overpriced, it’s hard to deny the effectiveness of a poo stick in warding off attackers. Which is exactly what the larvae of the tortoise beetles have been doing for millennia. Not content to just sit there and get eaten, using a highly elongated and mobile anus, they build a tower of poo on a special structure on their backs. It’s dextrous too: When threatened, the larvae can smack their foes with the so-called “fecal shield.”
Insects can opt to dump a whole lot of eggs into the ecosystem and just hope they make it on their own, but tortoise beetles are doting mothers, forming a system known as subsociality. A beetle mom begins by laying a cluster of eggs, typically on the underside of a leaf, at a very specific time of year: the rainy season. This ensures the young will have plenty of food when they hatch. When they do, she guards them fiercely, guiding them around as a herd to prime feeding locations.
|Enjoy this image of an adult tortoise beetle, because it’s going to be all poo and anuses from here on out.|
So, the shit shields. They’re all built on top of a structure called the anal fork that the larva can manipulate to reach any part of its body. Poke one on its left side, and it’ll give you a targeted smack right there. Or sometimes, the shield can be so big that the beetle is restricted to just flipping it up and down. Much of the structure is in fact old exoskeletons, which the beetle sheds and forces to the back of its body—exoskeletons that Chaboo suspects could sequester toxins, making the shield that much more effective.
|That translucent tube is the larva’s highly mobile anus, which is a sentence I just wrote.|
So how can the larva so deftly crap all over itself? “This part is quite hilarious because their anus—I’m talking to a man in California about the anus of a beetle larva—so the anus is this long tube that is extremely flexible and maneuverable,” Chaboo says. “So it can extend and deposit the feces exactly where they want to place it.”
What you end up with is a noxious weapon that the beetle can use either like a shield or a sword. And as a united brood, their effect is pretty damn intimidating. When threatened, even by something as simple as a scientist’s shadow passing over them, the larvae form up into a circle, pointing their butts and shields outward, as their mother charges around the perimeter. It’s just like buffalo circling around their babies with their business end facing out, only the beetles are wielding doo-doo instead of horns. How the young are communicating with their mother isn’t quite clear yet, though Chaboo suspects little squeaky noises they emit may have something to do with it.
An Ugly Duckling Becomes a Swan. Only With, Like, More Legs and Stuff
When the young make it to adulthood and finally part ways, they’ll ditch the shit shield in favor of more civilized garb. As an adult, the edges of their exoskeletons are actually clear, and their shape allows them to hunker down on a leaf or some such without exposing their legs to nippy predators. And they come in all manner of colors and iridescence, with males and females sometimes sporting entirely different shades.
Yet not all tortoise beetle males are like the others. Some fellas are shaped more like females, and Chaboo reckons these guys are sneakers. So instead of competing with larger rivals, as the big sluggers battle the sneakers slip past them and mate with the ladies undetected. (This brilliant little evolutionary trick actually happens elsewhere in the animal kingdom. Some smaller male cuttlefish, for instance, will change their color and posturing to mimic females, then sneak right under big males guarding a harem and have a romp.)
Some species of tortoise beetle can also change their color on the fly, though this probably doesn’t have to do with mating, since both sexes can pull it off (if it were just the males doing it to impress females, it’d be a different story). Their elytra, the wing covers that make a beetle a beetle, have a very special structure. “Think of a parking garage, with a roof and a floor and pillars that support the internal structure,” says Chaboo. “Fluid flows within that empty space. We suspect that by controlling the flow of fluid in that space these beetles can change their color.”
Read more at Wired Science
Jun 25, 2015
There are three known species of yeti crabs, and now, in a new paper, scientists have described the characteristics of one of these species – Kiwa tyleri — for the first time. K. tyleri is the only species of yeti crab known to reside in the Southern Ocean, off Antarctica.
Researchers first photographed this deep-sea animal in 2010 using a remotely operated submersible vehicle (ROV). But the ROV did more than snap a few pictures of the furry crabs (some of which you can see here); it also vacuumed up a few specimens from about 8,500 feet (2,600 meters) beneath the Southern Ocean’s icy surface, for further study.
Since then, researchers have studied the specimens using genetic sequencing and computed tomography (CT) scanning. Their description of the somewhat strange morphology of the yeti crab is published today (June 24) in the journal PLOS ONE.
Many of the yeti crab’s distinctive features — like its stark white coloring and its “hairy” body — are the creature’s adaptations to its habitat, the researchers said. K. tyleri dwells in a “thermal envelope” of just a few square meters, where the water is just the right temperature, said Sven Thatje, lead author of the report and associate professor of marine evolutionary ecology at the University of Southampton in England.
“They’re literally, in places, heaped up upon each other,” Alex Rogers, a professor of zoology at Oxford University who led the expedition to the East Scotia Ridge, told Live Science in 2012. Photographs taken by Rogers’ team show 600 crabs per square meter.
The reason for the crabs’ tiny living quarters is simple: The water just outside their cozy home is very cold, Thatje told Live Science in an email. Water temperatures at that depth of the Southern Ocean typically fluctuate between about 30 and 33 F (minus 1.3 to 0.5 C).
“Crabs and lobsters are very rare in Antarctic/Southern Ocean waters because of the unusually low seawater temperatures,” Thatje said. “A physiological limit to maintaining activities required for survival (ventilation, molting, mating) appears to exist at around 0.5 degrees C [32.9 degrees F].”
But some crabs do brave the icy waters away from the vents. Female yeti crabs leave the vents to brood their eggs, which researchers believe need cooler water to develop. The eggs would also be unlikely to survive so close to the hydrothermal vents’ sulfur-rich emissions, Thatje said. But these mama yeti crabs have a thankless job: Once they are done brooding, they usually die, Thatje said.
“Females that move off-site do not feed; in fact, they starve,” said Thatje, who hypothesizes that once the females leave the vents, they aren’t strong enough to fight their way back into the crustacean melee.
Yeti crabs survive by growing their own food, in a sense. The distinctive “hair” on their bodies that gives them their name is scientifically known as setae, and serves as a “garden” where the yeti crabs’ favorite food — bacteria — grow.
Unlike Kiwa puravida – the yeti crab found near hydrothermal vents off the coast of Costa Rica that has setae only on its appendages — the Antarctic yeti crab also has setae along the underside of its body. The appearance of this “chest hair” led scientists to nickname Kiwa tyleri the “Hoff crab” after “Baywatch” actor David Hasselhoff, who (as you may recall) has a hairy chest.
This difference in setae between the Antarctic yeti craband its two closest relatives, Kiwa puravida and K. hirsute (which inhabits the waters south of Easter Island, along the Pacific-Antarctic Ridge), is “remarkable,” Thatje said. It’s likely that the Hoff crabs’ hairy chests are an adaptation. Their luxurious setae allow the Hoff crab to not only grow its own bacteria, but also swipe up bacteria that grow on the vent chimneys.
Read more at Discovery News
Noctilucent or “night-shining” clouds, which appear sometime in late spring and last until the near the end of summer above the Earth’s polar regions, are the highest clouds in our planet’s atmosphere, floating nearly 50 miles (80 kilometers) above the surface.
They’re very cold and filed with tiny ice crystals, which when illuminated by sunbeams, turn into a glowing electric-blue.
That’s all pretty strange, but what’s even stranger is that they seem to be a relatively recent phenomenon in the Earth’s atmospheric history.
The first sighting of them was in 1885, two years after the massive eruption of the Indonesian volcano Krakatoa. 19th-century scientists originally believed that they were caused by volcanic ash in the atmosphere.
But after the ash settled, oddly, the noctilucent clouds didn’t go away. Instead, they’ve actually gotten brighter and become more common. They’ve also started appearing further south, with sightings in places such as Utah and Colorado. NASA says this could be a sign of the increasing greenhouse gases in the Earth’s atmosphere.
This year, the northern clouds also arrived a bit earlier than usual. NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite spotted what the agency’s website calls “a luminous patch of electric-blue” drifting across the Arctic Circle on May 19.
One interesting question about the northern noctilucent clouds is whether their behavior will shift.This year’s noctilucent clouds in the Southern Hemisphere were much more variable than usual, with a big drop off in cloud frequency 15 to 25 days after the summer solstice. That’s the time when they usually are most abundant.
The Guardian newspaper reports that scientists think this may be the result of altered conditions in the upper atmosphere, but nobody knows yet exactly what those changes are or what they mean.
Read more at Discovery News
The plane eventually crash-landed in the Azores and all survived (80 were hospitalized), but the experience became seared in the survivors’ brains.
Now brain imaging shows the trauma literally changed the survivors’ brains.
Brain imaging of eight of those passengers, conducted nine years later, revealed the memories of that terrifying experience remained crystal clear and lit up distinct areas of the brain related to memory, emotion and visual processing.
The event also appears to have heightened their reactions to other negative life events.
“This traumatic incident still haunts passengers regardless of whether they have PTSD or not,” lead researcher Daniela Palombo, a post-doctoral researcher at the Boston University School of Medicine, told the Toronto Star.
“They remember the event as though it happened yesterday, when in fact it happened almost a decade ago (at the time of the scans).”
The neuroimaging study — believed to be the first examination of a group of people who all experienced the same trauma — was published online in the journal Clinical Psychological Science (CPS).
“Research on highly traumatic memory relies on animal studies, where brain responses to fear can be experimentally manipulated and observed,” Brian Levine, senior scientist at Baycrest’s Rotman Research Institute, professor of psychology at the University of Toronto, and senior author on the paper, said in a press release. “Thanks to the passengers who volunteered, we were able to examine the human brain’s response to traumatic memory at a degree of vividness that is generally impossible to attain.”
For the study, eight survivors were placed inside a functional magnetic resonance imaging (fMRI) scanner. While inside the machine, they watched a video containing news clips related to the Air Transat flight and recalled their harrowing experience a decade ago.
The scanner showed that areas of the brain associated with emotional memory — the amygdala, hippocampus, and midline frontal and posterior regions – lit up very distinctly as they remembered the event.
The timing of the Air Transat incident permitted researchers to introduce another factor in their study. Since the attacks of 9/11 occurred just three weeks later, the researchers then asked the subjects to recall the less personal trauma of the terror attacks.
Read more at Discovery News
Until now, stellar rejuvenation has been pure conjecture, but after studying a white dwarf star called PG 0010+280, it turns out that one very interesting explanation for an excess in detected infrared radiation may be down to the presence of an exoplanet that was given a facelift.
White dwarf stars are the remnant husks of stars that have died. Eventually, when a star like our sun runs out of fuel, puffing-up into a red giant star, its layers of plasma will be blasted into space by powerful, suicidal stellar winds. This will create a beautiful planetary nebula with a small, dense white dwarf in the core.
But what happens to all this material that has been jetted into space? Well, as the theory goes, some of it may fall onto massive gaseous exoplanets orbiting far away from the star. Before their star ran out of hydrogen and puffed up into a red giant, that exoplanet was aging gracefully, cooling down billions of years after formation.
The situation changed, however, when its atmosphere became bulked up with stellar plasma, re-heating the massive world and making it appear much younger than it really is.
“When planets are young, they still glow with infrared light from their formation,” said Michael Jura of the University of California, Los Angeles, co-author of the study published in The Astrophysical Journal. “But as they get older and cooler, you can’t see them anymore. Rejuvenated planets would be visible again.”
White dwarf studies have gone into overdrive in recent years after astronomers realized they could study white dwarf atmospheres to find the pulverized remains of asteroids and planetary bodies. When passing into the white dwarf phase, the planets and asteroids that are in orbit may drift too close to the powerful tidal forces near that star, and become shredded.
During a survey of white dwarfs for the chemical signatures of these pulverized planetary remains, undergraduate student Blake Pantoja, who was studying at UCLA at the time, came across something weird in data from NASA’s Wide-field Infrared Survey Explorer and follow-up study by NASA’s Spitzer Space Telescope confirmed the strange excess in infrared light coming from PG 0010+280. At first the team assumed the excess was radiating from a disk of the pulverized remains of asteroids that may have been present — but the data didn’t fit with this explanation.
Read more at Discovery News
This is according to the instruments aboard NASA's MAVEN spacecraft, which made the first direct detection of sodium, magnesium, aluminum, chromium, nickel, copper, zinc, iron and other metals high in the Martian atmosphere that can be linked directly to the material sloughing off the comet.
“This must have been a mind-blowing meteor shower,” said Nick Schneider of the Laboratory of Atmospheric and Space Physics at the University of Colorado.
MAVEN's instruments were put to use as soon as the spacecraft arrived -- even before the instruments were fully commissioned -- to measure the effects of the comet on the Martian atmosphere.
Based on the strong signal of magnesium and iron measurements seen by MAVEN's Imaging Ultraviolet Spectrograph, Schneider says the hourly meteor rate overhead on Mars must have been tens of thousands of “shooting stars” per hour for hours.
“I'm not sure anyone alive has ever seen that,” said Schneider, “and the closest thing in human history might the the 1833 Leonid shower.”
The metal ions were the remains of pebbles and other pieces shed from the comet that burned up, or “ablated” into individual atoms -- when they hit the Martian atmosphere at 56 kilometers per second (125,000 miles per hour). It's the same thing that happens on Earth, except that not even on Earth had a spacecraft been in the right place at the right time to detect so many ions fresh off a comet.
“This is the first time that we detect the full panel of metal ions from sodium to zinc,” said Mehdi Benna, a MAVEN researcher at the University of Maryland and NASA's Goddard Space Flight Center who works on the team that runs the Neutral Gas and Ion Mass Spectrometer (NGIMS).
That instrument captures, identifies and counts the charged metal atoms high in the ionosphere of the red planet. Only, the first measurements NGIMS did were under unprecedented and unexpected circumstances, he said.
“The nice thing about Comet Siding Spring is that we know the source of the dust particles,” said Benna. “We know the source and the speed.” These are numbers they can put into the models they use to sort out the details of such events and glean information about Mars' ionosphere, the comet's composition, and even the workings of Earth's ionosphere when it's hit by comet or asteroid debris. “Here we really have a controlled experiment. We measured ions shortly after they has deposited. If we had waited a week or even a few days we wouldn't have such a clear detection.”
Benna and Schneider are lead authors on separate papers about their respective instruments' measurements recently published online by the journal Geophysical Research Letters. One of the things that can not be found those papers, however, is the role serendipity played in the work. MAVEN was not launched with Comet Siding Spring in mind. It was just luck that the spacecraft arrived in time for the flyby with instruments that could study the event.
Read more at Discovery News
Jun 24, 2015
Images from New Horizons, currently within 15 million miles of its target, show Pluto is an orangey beige color and Charon is gray.
“The scientists are mulling over that one,” Lisa Hardaway, a manager with New Horizons camera-builder Ball Aerospace, told Discovery News. “They were expecting the two objects to be of the same material, but they’re obviously not.”
Even before the difference in color was known some scientists theorized that Charon coalesced from debris jettisoned into space after an object smashed into Pluto. A similar event is believed to be responsible for forming Earth’s moon.
Charon, which was discovered in 1978, is nearly half the size of Pluto and it has enough mass to be a co-orbiting partner, the only known binary pair in the solar system.
Like Earth’s moon, one side of Charon permanently faces its parent body, a configuration known as tidal locking. But Charon never rises or sets in Pluto’s skies, appearing pinned over the same patch of real estate.
Like the gas giant Uranus, Pluto and Charon rotate the sun tipped on their sides, possible evidence of a massive impact.
Among the mysteries New Horizons should be able to solve is whether any of Pluto’s atmosphere is winding up at Charon.
Computer models dating back to the late 1980s show that particles escaping from Pluto’s atmosphere have to pass Charon’s orbit, said New Horizons lead researcher Alan Stern, with the Southwest Research Institute in Boulder, Colo.
“Charon’s gravity can pull some of that atmospheric gas into orbit around itself or even onto the surface of Charon and create a secondary atmosphere,” Stern said. “We’re on the lookout for that.
“This would be fantastic if we discovered something like this,” he added. “Never in the history of planetary exploration have we seen two bodies with a shared atmosphere like we may see at the Pluto system. It could be quite a wonderland.”
Images released on Monday show a distinct, and unexplained, dark region on Charon’s north pole.
Read more at Discovery News
This past week, a team of researchers using the now-dead Venus Express spacecraft revealed hotspots on the surface shooting up by several hundred degrees. Their best guess as to what’s happening? Lava from active volcanoes.
We all know that Venus is a hellish world that killed some Soviet landers in minutes. Its average surface temperature would easily melt lead. But even on the surface trapped in a runaway greenhouse effect, the hotspots stood out. So what do we know about volcanoes on Venus?
Recent lava flows were first reported in 2010, when data from Venus Express was compared to the older NASA Magellan spacecraft, which mapped elevations. Scientists saw compositional differences in the lava-soaked terrain compared to what was around it — specifically, minerals that are abundant in lava on Earth.
Why are volcanoes so important? One reason is they reveal what is happening on the insides of the planet. And what we know shows that Venus was or is extremely active. The planet has more than 1,600 large volcanoes or volcanic features and many smaller ones, according to Oregon State.
But here’s the rub (literally) — plate tectonics don’t appear to be involved in a big way. On Earth, colliding tectonic plates create volcanic activity. But the chains of volcanoes and rifts on our planet aren’t in evidence on Venus.
Read more at Discovery News
"Grandfather turtle," as it has been named, could help to solve longstanding debates about the amazing family tree of all turtles. One theory is that turtles are living dinosaurs, as birds are, but this study, published in Nature, concludes that turtles are more closely related to lizards and snakes.
While it's hard to imagine a slow and hefty turtle slithering on the ground, senior author Hans-Dieter Sues points out, "Snakes are just a large group of legless lizards."
He added that the ancestor that gave rise to turtles would have been "a small, superficially lizard-like reptile with expanded trunk ribs."
Sues and colleague Rainer Schoch analyzed the remains of Grandfather turtle (Pappochelys rosinae), which were found at Schumann quarry in Germany. Based on the anatomy, they do classify turtles as being a "diapsid," a group that includes dinosaurs, birds, pterosaurs, other extinct species, crocodiles, lizards, snakes and the tuatara, which is a lizard-like reptile.
Sues and Schoch, however, believe that turtles are far more related to lizards and snakes than they are to the other major diapsid lineage, which includes dinosaurs and birds.
Eight-inch-long Grandfather turtle did not have a shell, but it certainly had the makings of one, given its broad "T"-shaped ribs and a hard wall of bones along its belly.
"This configuration of the ribs would have immobilized them and led to the development of a novel way of breathing in turtles," Sues said. "Modern developmental studies indicate that the turtle shell formed from bony outgrowths of the vertebrae and ribs."
As for why this happened, the researchers theorize that the turtle shell may have originally developed in water-dwelling reptiles.
"Its main role would have been all-around protection of the vital organs," Sues said, adding that the shell initially might have also "helped with buoyancy control by making the animal heavier."
Tyler Lyson, curator of vertebrate paleontology at the Denver Museum of Nature & Science, and a leading expert on the evolution of turtles and dinosaurs said the study "is a very important contribution in addressing who turtles are related to, as well as the evolutionary origin of the turtle shell."
Read more at Discovery News
The bizarre animal, appropriately named Hallucigenia sparsa, suggests that the common ancestor of everything from black widow spiders to giant lobsters was far more complex than previously suspected. A common aspect of most of these animals, including spiders, is that they molt.
“It turns out that the ancestors of molting animals were much more anatomically advanced than we ever could have imagined,” co-author Jean-Bernard Caron, curator of invertebrate paleontology at the Royal Ontario Museum, said in a press release.
Caron added that Hallucigenia and its kind were “ring-like plate-bearing” species “with an armored throat and a mouth surrounded by spines.”
Hallucigenia was so bizarre that, for years, scientists couldn’t figure out which side of it was the front and which was the back. Some researchers even mistakenly drew the creature upside down.
“Prior to our study, there was still some uncertainty as to which end of the animal represented the head, and which the tail,” said co-author Martin Smith of Cambridge University’s Department of Earth Sciences.
He added, “A large balloon-like orb at one end of the specimen was originally thought to be the head, but we can now demonstrate that this actually wasn’t part of the body at all, but a dark stain representing decay fluids or gut contents that oozed out as the animal was flattened during burial.”
New fossils for its head, outlined in the latest issue of Nature, were unearthed in the Burgess Shale of Yoho National Park in western Canada. They reveal that Hallucigenia had a long head with a pair of simple eyes, which sat above a mouth that featured a ring of teeth-like needles. The latter were probably helped to generate suction, flexing in and out, like a valve or plunger, order to suck food into the organism’s throat.
The researchers speculate that the “needles” in the throat worked like a ratchet, keeping food from slipping out of the mouth each time it took another “suck” at its food. (Later animals, such as fish, evolved actual teeth as we know them, which permitted biting and chewing of food.)
Read more at Discovery News
Jun 23, 2015
The international team found the so-called blue hook stars throw off their cool outer layers late in life because they are rotating so rapidly, making them more luminous than usual.
"We've solved an old puzzle. These stars are only half the mass of our Sun yet we could not explain how they became so luminous," said team member Dr Antonino Milone, from The Australian National University (ANU) Research School of Astronomy and Astrophysics.
"As the star was forming billions of years ago from a disc of gas in the congested centre of the star cluster, another star or stars must have collided with the disc and destroyed it."
The research, published in Nature, gives new insights into star formation in the early Universe in the crowded centres of clusters. Star clusters are rare environments in the Universe, in which many stars are born at the same time.
The team studied the globular cluster Omega Centauri, the only cluster visible to the naked eye, which contains around 10 million stars in close proximity to one another.
The model shows the formation of stars in clusters do not all form at once, said co-author Dr Aaron Dotter, also from ANU Research School of Astronomy and Astrophysics.
"These blue stars must form in a second generation of star formation," he said. "Our new explanation is quite simple, and it hangs together really nicely."
Usually the large disc of ionised gas around a newly-forming star locks its rotation through magnetic effects. For the progenitors of blue hook stars, however, an early destruction of its disc allows the stars to spin up as the gas comes together to form a star.
Because its high rotation rate partially balances the inward force of gravity, the star consumes its hydrogen fuel more slowly and evolves differently throughout its life.
Read more at Science Daily
That's among the questions University of Washington doctoral student Edward Schwieterman and astronomer Victoria Meadows of the UW-based, interdisciplinary Virtual Planetary Laboratory sought to answer in research published in May in the journal Astrobiology.
Using computer simulations, the researchers found that if organisms with nonphotosynthetic pigments -- those that process light for tasks other than energy production -- cover enough of a distant planet's surface, their spectral signal could be strong enough to be detected by powerful future telescopes now being designed. The knowledge could add a new perspective to the hunt for life beyond Earth.
Such organisms 'will produce reflectance, or brightness, signatures different than those of land vegetation like trees,' said lead author Schwieterman. 'This could push us to broaden our conception of what surface biosignatures might look like' on an exoplanet, or world beyond our solar system.
He said the research grew from a meeting with co-author Charles Cockell of the UK Centre for Astrobiology in 2012. Schwieterman sought a topic for a research rotation in the UW Astrobiology program in which students do work outside their main field of study.
'I was interested in doing biology in the lab and linking it to remotely detectable biosignatures, which are indications there is life on a planet based on observations that could be made from a space-based telescope or large ground-based telescope,' Schwieterman said.
There had already been literature about looking for something akin to Earth's vegetation 'red edge' as a possible biosignature on exoplanets, he said. The red edge -- caused by oxygen-producing organisms such as trees -- is the increase in brightness when you move from the visible wavelength range to the infrared, or light too red to see. It's why foliage looks bright in infrared photography and is often used to map vegetation cover by Earth-observing satellites.
Schwieterman and Cockell, a University of Edinburgh astrobiologist, decided to look further, and measure the reflectance of earthly organisms with different kinds of pigments. They included those that do not rely on photosynthesis to see what biosignatures they produce and how those might differ from photosynthetic organisms -- or indeed from nonliving surface features like rocks and minerals.
Pigments that absorb light are helpful to earthly organisms in ways other than just producing energy. Some protect against the sun's radiation or have antioxidants to help the organism survive extreme environments such as salt concentrations, high temperatures or acidity. There are even photosynthetic pigments that do not produce oxygen at all.
Schwieterman and Meadows then plugged their results Virtual Planetary Laboratory spectral models -- which include the effects of the atmosphere and clouds -- to simulate hypothetical planets with surfaces covered to varying degrees with such organisms.
'With those models we could determine the potential detectability of those signatures,' he said.
Exoplanets are much too far away to observe in any detail; even near-future telescopes will deliver light from such distant targets condensed to a single pixel. So even a strong signal of nonphotosynthetic pigments would be seen at best only in the 'disk average,' or average planetary brightness in the electromagnetic spectrum, Schwieterman said.
'This broader perspective might allow us to pick up on something we might have missed or offer an additional piece of evidence, in conjunction with a gaseous biosignature like oxygen, for example, that a planet is inhabited,' Schwieterman said.
The UW-based planetary lab has a growing database of spectra and pigments of nonphotosynthetic organisms and more that is available to the public, and to which data from this project have been added.
Read more at Science Daily
Islands are seen as natural laboratories for the study of evolution. They form isolated ecosystems with barriers to migration. Classical Island Theory predicts that a dynamic equilibrium will occur between immigration and extinction of species. Recent theory adds that as species diversity increases, ever more ecological niches become occupied, which has a negative effect on immigration (new immigrants from outside of the Galápagos cannot settle) and diversification (radiation into new species is blocked).
'However, this has never been tested in detail, for lack of data and the right analytical tools', explains Rampal Etienne, Associate Professor of Theoretical and Evolutionary Community Ecology at the University of Groningen, the Netherlands. Together with Luis Valente (University of Potsdam, Germany) and Albert Phillimore (University of Edinburgh, UK), he developed DAISIE, a mathematical model that uses phylogenetic data on living species to reconstruct evolutionary dynamics. DAISIE stands for Dynamic Assembly of Islands by Speciation, Immigration and Extinction, and was named after famous radiations of daisy-like plants on Hawaii.
DAISIE was fed with the phylogenetic trees of existing bird species on the Galápagos Islands. These were constructed with genomic data that has become available in recent years. DAISIE then estimates diversity limits and rates of immigration, speciation and extinction per lineage.
'The analysis shows that for the finches, diversity does indeed have a negative effect. There is no more room for new species, unless one of the existing species becomes extinct, so the islands are saturated regarding finch-type species', Etienne explains. This does not mean the radiation is static. 'We found that the rates of both evolution and extinction are very high for Darwin's finches. That is probably why these birds have reached an equilibrium.'
Other species like mockingbirds have not yet reached equilibrium, which contrasts sharply with the current view that oceanic islands are at equilibrium. 'Our data shows that they are evolving more slowly and are still diversifying.' In a million years or so, more mockingbird species may have appeared -- granted that conditions on the islands remain the same.
The study shows that the DAISIE model -- which the authors have made available as a library* in the free and widely used R software environment -- is a valuable tool for the study of evolutionary dynamics on islands. It includes speciation and thus extends existing island theory, which is based on immigration and extinction. Etienne: 'And of course, it works for all isolated ecosystems, not just islands but also lakes or mountain tops.'
Read more at Science Daily
The findings have now been published in the geoscience journal Palaeontologia Electronica.
In 2003, a private fossil collector made a surprising discovery in a limestone quarry near Goslar in Lower Saxony: a total of 20 dinosaur footprints imprinted on a stone slab. Nils Knötschke, from Dinosaur Park Münchehagen, was able to salvage five of the tracks and kept them from being destroyed by the quarry work. Now, about a dozen years later, paleontologists from the University of Bonn, led by Prof. Dr. Martin Sander, have worked with Nils Knötschke and Dr. Oliver Wings from the State Museum of Hanover to reconstruct the tracks in a three-dimensional model, using digital methods. The project was based on photos of the tracks taken at the time when they were excavated.
"Even five years ago, it wouldn't have been technically possible to do this kind of reconstruction," says first author Jens N. Lallensack of the Steinmann Institute for Geology, Mineralogy and Paleontology at the University of Bonn. Based on the 3D model, the researchers were able to gain crucial information about the dinosaurs that left the footprints behind, and about their habitat at the time. The tracks, measuring between 36 and 47 centimeters in length, probably represent two different species of predatory dinosaurs from the Theropoda group.
Glimpses of the habitat 154 million years ago
Based on the digital model, we can now see how the individual footprints are positioned in relation to one another. "That allowed us to reconstruct the moving direction, and how fast the animals were traveling. Based on the length of the footprints, we can estimate that the largest animals had a body length of about eight meters. In some places, the carnivorous dinosaurs also left much deeper tracks in the sediment than elsewhere. "Where the ground was soft, the dinosaurs sank in much deeper than where it was dry," reports Lallensack.
About 154 million years ago, during the Late Jurassic Era, there was a shallow sea throughout this region, with small islands jutting up out of it. Bones found in the Langenberg Quarry confirm that the islands were inhabited by a species of small dinosaurs, Europasaurus holgeri. These herbivores belonged to the group of gigantic, long-necked dinosaurs called sauropods. However, a full-grown Europasaurus only measured six to eight meters -- about one-fourth the length of its nearest relative, Camarasaurus. "The dinosaur probably had to shrink down to dwarf size in order to survive, given the limited food available on these small islands in the shallow Central European sea," says Lallensack.
Theropods probably immigrated via a land bridge
The theropods that originally made the reconstructed dinosaur tracks came on the scene about 35,000 years later. "It's possible that the sea level dropped during this period -- a relatively short time from a geological perspective -- and that the mainland carnivorous dinosaurs immigrated at that point," surmises Dr. Wings, who is heading a research project funded by VolkswagenStiftung at the State Museum of Hanover on the overall Jurassic habitats of the region. The theropod tracks come from a dried-up ocean floor bed very close to one of the islands.
Read more at Science Daily
The auroras were seen as far south as Philadelphia and northern New Jersey last night (June 22), and gave astronauts aboard the International Space Station a stunning celestial light show. The solar storm that caused the auroras was declared a level G4 (severe), with a maximum possible ranking of G5 (extreme).
Auroras, also known as the northern and southern lights, are caused by bursts of powerful particles ejected from the sun that collide with Earth’s atmosphere. The solar storm behind last night’s spectacular light display continues to rage, and officials say auroras should be visible again tonight (June 23) for viewers in Canada and parts of the U.S.
Photographer Jeff Berkes snapped photos of the rippling northern lights over a field in southern Philadelphia. In an email to Space.com, Berkes said these were the most intense northern lights he has ever seen in this location.
Meteorologist Eric Holthaus wrote in an article for Slate that the coronal mass ejection had picked up two smaller, slower ejections from last week, building in power as the particles raced toward Earth. Once there, they whipped up a geomagnetic storm as the Earth’s magnetic field adjusted to the new addition — and the results could be seen all across the northern United States and Canada.
The solar storm erupted from the sun during the day on Sunday (June 21). As the sun belched out a fiery solar flare, it also released a huge coronal mass ejection — a stream of charged particles. The size and strength of this particular particle ejection were dubbed “impressive” by scientists working on NASA’s Advanced Composition Explorer mission as the storm shot by the ACE spacecraft on the way to Earth Sunday afternoon.
A solar storm lit up the night sky above Mammoth Hot Springs last night. #AuroraBorealis #NorthernLights pic.twitter.com/s9x79docjv — YellowstoneNPS (@YellowstoneNPS) June 23, 2015
The storm reached severe levels as of 1:13 a.m. EDT (0513 GMT) today, according to the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center, and fast solar wind conditions and strong magnetic fields will likely continue — meaning auroras will likely be visible again tonight for lucky skywatchers.
Read more at Discovery News
At least eight bright areas now have been found next to a large white region glinting inside the crater. Scientists suspect they are seeing some kind of highly reflective material, such as ice or salt, but there are other options as well, like geysers, volcanoes or rock.
The new images, which were taken on June 9 and released today (June 22), also show that Ceres has a steep, three-mile high mountain rising from the surface in an area that is otherwise relatively smooth and flat.
In August, Dawn is scheduled to make more observations of Ceres from a lower orbit just 900 miles above the surface.
From Discovery News
Jun 22, 2015
Known as Passo Marinaro, the cemetery near the coastal town of Kamarina in southeastern Sicily, was in use from the 5th through 3rd centuries B.C. The necropolis has yielded approximately 2,905 burials; more than half contained grave goods, mostly terracotta vases, but also figurines and metal coins.
Two of the tombs were unique.
One body, found in a tomb labeled 653, contained an individual of unknown sex, who apparently experienced a period of serious malnutrition or illness in life.
“What is unusual about Tomb 653 is that the head and feet of the individual are completely covered by large amphora fragments,” Carrie Sulosky Weaver, an archaeologist at the University of Pittsburgh, wrote in Popular Archaeology.
An amphora is a large, two handled ceramic vessel that was generally used for storing wine and olive oil.
“The heavy amphora fragments found in Tomb 653 were presumably intended to pin the individual to the grave and prevent it from seeing or rising,” Sulosky Weaver said.
The other burial, labelled 693, contained the remains of a child of indeterminate sex about 8 to 13 years old. No signs of diseases were found on the remains, nevertheless the child was buried with five large stones placed on top of the body.
“It appears that these stones were used to trap the body in its grave,” Sulosky Weaver said.
Her research will be featured in a forthcoming book, “The Bioarchaeology of Classical Kamarina: Life and Death in Greek Sicily,” which will be published by the University Press of Florida in September.
It is unknown why the occupants of those burials were pinned in their graves, but “their special treatment suggests that necrophobic beliefs and practices were present in Greek Sicily,” Sulosky Weaver said.
“Necrophobia, or the fear of the dead, is a concept that has been present in Greek culture from the Neolithic period to the present,” she added.
Read more at Discovery News
The discovery was unexpected for researchers at the University hospital in Lund who hoped to learn more about the health and lives of people from that period by examining the remains of the extremely well preserved Bishop Peder Winstrup.
“You can only speculate as to whether it was one of Winstrup’s next of kin, or whether someone else took the opportunity while preparing the coffin. But we hope to be able to clarify any kinship through a DNA test,” said Per Karsten, director of the historical museum at Lund University, in a press release.
Karsten said the fetus could be related to Winstrup, who was one of the founding fathers of Sweden’s Lund University. But perhaps more likely, Karsten said, the fetus was placed there by someone with access to Winstrup’s coffin in order to have an illegitimate child buried in sanctified ground.
The preliminary results of the scan also revealed that the body still hosts most of the internal organs — unusual for a mummy.
The bishop wasn’t preserved by the usual mummification process but simply dried out naturally. The good condition of the body appears to be the result of ideal conditions — constant air flow, plant material in the coffin, a long period of illness for the bishop before death, causing him to be very lean, and the fact that he was buried during the winter months.
Analysis of the remains suggest the 74-year-old had gallstones, which could indicate a diet of fatty foods, and tooth decay possibly resulting from eating a lot of sugar. The bishop also appeared to suffer from osteoarthritis in both the knee and hip joint — and a bad shoulder.
“His right shoulder was slightly higher than his left, due to an injury to a tendon in the shoulder. This would have limited Winstrup’s mobility, making it difficult for him to carry out simple everyday tasks such as putting on a shirt or combing his hair with the comb in his right hand,” Caroline Ahlström Arcini, an osteologist working on the project, said in a press release.
Read more at Discovery News
Because large segments of the individual’s chromosomes are of Neanderthal origin, a Neanderthal was among the man’s ancestors as recently as four generations back in his family tree, reports a study published in the latest issue of the journal Nature.
The finding reveals that some of the first members of our species who came to Europe interbred with the local Neanderthals.
To this day, individuals of European and Asian heritage retain Neanderthal DNA in their genomes, but whether or not Neanderthals went extinct or simply were absorbed into the modern human population remains a matter of definition, senior author Svante Pääbo told Discovery News.
“Some Neanderthals clearly became incorporated in modern human societies,” said Pääbo, director of the Department of Evolutionary Genetics at the Max Planck Institute for Evolutionary Anthropology. “It is still unclear exactly how much of the complete Neanderthal genome exists today in people, but it seems to approach something like 40 percent.”
“But, of course, the Neanderthals are clearly extinct in the sense that they do not exist as an independent, separate group since some 30,000 or 40,000 years.”
David Reich from Harvard Medical School coordinated the population genetic analysis of the study, which was an international effort. At the center of the research were the remains of the man, named “Oase 1,” unearthed at a cave system called Peștera cu Oase in Romania.
The researchers believe that the man derived from the same expansion out of Africa as other modern people, but was likely to have been part of an early “pioneer foray into Europe,” ahead of other migrations that were to come later.
Under what conditions his relatives, and those of other early Neanderthal-human hybrids, interbred is a big question.
Chris Stringer, an expert on early humans at the Natural History Museum in London, posed some intriguing questions about the matings.
“Were these peaceful exchanges of partners, raids which stole women or girls, or even the adoption of orphaned babies?” he asked, adding that the answer remains a mystery.
What is clear is that the interbreeding took place at different times and locations. This particular individual, Oase 1, did not contribute much, if at all, to later modern human populations, however. Pääbo explained that whatever population he represented seems to have “disappeared,” leaving behind no known tools or other artifacts.
“There are several studies now that show East Asians and Native Americans have about 20 percent more Neanderthal contribution (in their genomes) and that this could be due to extra inbreeding in the ancestors of East Asians,” Pääbo explained.
Other studies also conclude that there was likely a natural selection against a Neanderthal contribution to the Homo sapiens genome, such that even if interbreeding were very common, the evidence for that would not fully reveal itself in the genomes of modern humans of European and Asian heritage.
“In the case of the Neanderthal gene flow into modern humans, it is clear that much of that DNA has been lost or selected away since, but there are some examples where it may have been retained because it was advantageous to the modern groups receiving it,” Stringer said, adding that he was surprised that interbreeding between Neanderthals and Homo sapiens “was still happening long after 55,000 years ago.”
Read more at Discovery News
NASA announced last week that it’s one step closer to flying by Europa dozens of times after launching in the 2020s. The mission concept was approved and funding is ongoing. To get under that ice (virtually) NASA could include a radar instrument called REASON (Radar for Europa Assessment and Sounding: Ocean to Near-surfaces) to peer underneath. But what if we were to eventually send a robotic landing mission?
Britney Schmitt, a member of the Europa mission team, told a conference last week that her team in Antarctica is testing out the very techniques that could be used in the ice, hundreds of millions of kilometers away.
At McMurdo Station in Antarctica last year, a mini-machine called Icefin dove under the ice to check out what’s sitting underneath the shelf. That was no small feat, given that the ice is tens of meters thick. The resulting video shows what’s lurking on the seafloor. Even to Earth-accustomed eyes, it looks kind of alien.
Icefin (Schmidt is principal investigator) is powerful, but small enough that it can be carried by people. The tethered underwater vehicle even breaks down into pieces to make it easier to transport. The instruments on board are supposed to measure things such as the ice, what’s in layers of water and what’s living on the seafloor. It can dive as deep as 1,500 meters (4,921 feet) and is designed to travel at least three kilometers (1.86 miles) underwater.
Schmidt characterized the work, which is led by Georgia Tech, as key to helping with NASA’s proposed Europa mission. “Personally, I’m proud to be a part of the mission team. I’ve helped on studies for a while, and it’s just been a large group of people working for the past 20 years to get this mission going,” she said.
Read more at Discovery News
These discoveries could help explain what created the tiny system -- or they could destroy New Horizons before it has a chance to relay its precious data.
"The New Horizons mission provides an opportunity to reveal the compositions of the moons," said Richard Binzel, a member of the mission's science team and a planetary scientist at the Massachusetts Institute of Technology. "The compositions are the next step to decoding their origins."
Telescope studies have found that the moons vary a great deal in brightness. That suggests they are made of different mixes of materials, and so they have different origins and were possibly captured by Pluto at different times. On the other hand, their neatly arranged orbits around Pluto strongly suggest the opposite: that they formed at the same time, perhaps from an ancient collision that left Pluto orbited by Charon, the other moons and perhaps rings of debris.
The currently most accepted theory is the collision, which gives the Pluto-Charon, et al., system a lot in common with the Earth-Moon system, that is thought to have formed in the same manner when a Mars-sized body slammed into the early Earth and created our unusually large natural satellite.
"Charon is half as big as Pluto," said Mark Showalter, a planetary scientist at the SETI Institute who is involved in efforts to search for hazardous debris along New Horizons' flight path at Johns Hopkins University Applied Physics Laboratory. "So that's the consensus: Charon is debris from this collision."
But the collision picture is far from complete.
"The question is the little guys," said Showalter, meaning the smallest moons Styx, Nix, Hydra and Kerberos. The collision theory sounds really good, he said, except that no one has been able to reproduce the system accurately in a model. So all bets are off until there is more data -- which New Horizons could very well provide.
"If you fly through this system at 14 kilometers per second (31,000 miles per hour), anything larger than a BB could do damage to the spacecraft," said Showalter. Of course, at 3 billion miles away, there no way to see something that small. So the researchers are focusing on the things that can shed dust and gravel in the vicinity of Pluto.
"In terms of danger to the spacecraft, we are not too worried about any moons outside Charon in near-equatorial orbits," Showalter said. "The reason is that any dust they generate is not likely to get into the path of the spacecraft. We are most concerned about something close to Pluto and/or in a very inclined orbit."
To minimize the danger, Showalter and a team of about ten people are analyzing and modeling every bit of new data as New Horizons approaches Pluto. They are on the lookout for any small moons or faint rings that might not have been seen previously.
Read more at Discovery News
Jun 21, 2015
“In a way, we can also say that we have life imitating art,” study lead author Paul Savage, a research scientist in the Department of Earth Sciences at Durham University in the United Kingdom, said in a statement.
“For millennia, tales have been told of the underworld being awash with fire and brimstone. Now at least, we can be sure of the brimstone.”
The researchers estimate that the Earth’s core contains 10 times the amount of sulfur than in the rest of the world, or comparable to about 10 percent of the mass of the moon.
Scientists have generally understood that at the time of Earth’s formation, heavy metals such as iron and nickel sunk to the planet’s core, and light elements, like oxygen, silicon, aluminum, potassium, sodium, and calcium, mostly concentrated in the outer layers of the Earth, in the mantle and crust.
However, the mass of the Earth’s solid inner core, which is too light to be composed solely of metal, has been an enduring inconsistency in our understanding of the planet’s distribution of elements. To explain the core’s lighter-than-expected weight, scientists assumed that the core had to contain some lighter elements, such as oxygen, carbon, silicon and sulfur.
“Scientists have suspected that there is sulphur in the core for some time, but this is the first time we have solid geochemical evidence to support the idea,” Savage said.
Confirming the presence of lighter elements, like sulfur, in the core, provides information about the temperatures, pressures and oxygen content in the Earth’s mantle, which surrounds the core and separates it from the crust on which we walk. “It’d be nice to know what the Earth is formed of, as a fundamental aspect of understanding the Earth,” Savage told Live Science.
Peeling back the layers
Without the technology to dig 1,800 miles (2,900 kilometers, or the equivalent of around 3,000 Eiffel Towers stacked on top of one another), scientists looked for clues created by a 4.47 billion-year-old impact — the moon-forming collision between Earth and a large, planet-size body called Theia.
“The giant impact wouldn’t have just formed the moon; it wouldn’t have just sort of sliced a bit of material off and end up becoming the moon,” Savage said. “The amount of energy involved in this sort of impact would have, if not completely, it would have partially melted the Earth’s mantle to a certain depth.”
When the mantle melted, some of its sulfur-rich liquid seeped into the core, and some of it evaporated into space, he added.
“You could lose a lot of it during evaporation,” Savage said. “Just by looking at the sulfur, we can’t really tell much about how much is in the core versus how much has been lost to space,” making sulfur virtually impossible to directly measure.
To track and quantify the elusive sulfur, the researchers looked to copper isotopes (atoms of the same element with different numbers of neutrons). “We chose copper, because it is a chalcophile element, which means it prefers to be in sulphide-rich material — so it is a good element to trace the fate of sulphur on Earth,” Frédéric Moynier, the study’s senior author and a professor at the Institut de Physique du Globe in Paris, said in a statement.
“Generally, where there is copper, there is sulphur; copper gives us a proxy measurement for sulphur.”
Searching for sulfur
The researchers measured the copper isotope values from both the mantle and core to discover where they would find sulfur. Meteorites were used to represent the “bulk Earth,” which includes the core, mantle and crust. Meteorites are jumbles of extraterrestrial matter that have been orbiting the sun since even before planets formed.
“They’re like cosmic sediments,” Savage said. “If we got a planet and milled it down, if we sort of crushed it up and mixed it around, that’s what we assume would be in meteorites.”
Samples formed from lava eruptions, as well as from tectonic events, which pushed the mantle onto the surface of the Earth, were used to represent so-called “bulk silicate Earth” values, which include the copper content in the mantle and crust. Researchers can then figure out the copper content in the Earth’s core by subtracting the “bulk silicate Earth” value from the “bulk Earth” value.
The scientists measured a heavy “bulk silicate Earth” copper isotope value compared with the “bulk Earth” value, which could indicate that the mantle has a lot of heavy copper and the core does not.
However, through experiments, they found that the “copper in the core should be slightly heavy compared to the mantle — so the core cannot balance out the heavy mantle compared to meteorites, because it is also heavy,” Savage said. If there are a lot of heavy copper isotopes in one part of the Earth, another part will have a lot of light copper isotopes.
To explain copper’s “heaviness” in both the mantle and core, the researchers predicted that a sulfur-rich liquid with “light” copper formed after the impact that created the moon.
“So the [melted mantle] is light, the mantle is heavy, and the two, when mixed together, would equal bulk Earth (meteorites),” Savage said.
After the Earth formed from meteorites and other extraterrestrial matter like dust and rock, it started to melt, forming its core. During core formation, some “heavy” copper left the melting mantle and entered the core, leaving the mantle with “lighter” copper, Savage said. Then, following the giant moon-forming impact, the Earth’s mantle re-melted, forming a sulfur-rich liquid.
Read more at Discovery News