- New Technique Finds Gaseous Metals in Exoplanet Atmospheres
- Sea Creatures Hint at Recent Trans-Antarctic Seaway
- Tube Full of Plasma Creates Solar Eruption in the Lab
- The Identifiable Victim Bias
- Drill Down: Going Deep With NYC’s Second Avenue Subway Project
- Heaps of Fossils From Evolutionary ‘Big Bang’ Discovered
- New Predatory Dinosaur Discovered in Romania
- In Search of Time
Posted: 31 Aug 2010 04:15 PM PDT
A previously undetected element has been found in the atmospheres of two different extrasolar planets. Using a new technique at a new telescope, two separate groups of exoplanet scientists have discovered potassium in the atmospheres of two hot Jupiters more than 190 light-years from Earth.
"I'm really excited about this," exoplanet expert Sara Seager of MIT, who was not involved in the new discoveries, said in an e-mail. "Together with other ground-based advances it is changing exoplanet atmosphere studies in a huge way."
The two groups, one led by exoplanet scientist David Sing of the University of Exeter and the other led by University of Florida grad student Knicole Colón, used the 34-foot-wide Gran Telescopio Canarias in the Canary Islands to observe the planet XO-2b, located around 500 light-years from Earth, and the planet HD 80606b, about 190 light-years from Earth.
Both planets pass in front of their stars, or transit, from the vantage point of Earth. As the planet crosses its star's face, some of the light from the star seeps through the glowing ring of the planet's upper atmosphere. Different atoms and molecules interact with light in specific ways, so observing the light that makes it through the atmosphere allows scientists to figure out what elements it contains.
The two teams both used a new technique called narrowband transit spectrophotometry to focus in on potassium. Earlier studies of exoplanet atmospheres looked at all the light passing through the planet's atmosphere, which restricted them to studying only the brightest stars. But Sing, Colón and their colleagues used a special filter that looks only at the particular wavelengths of light where potassium was expected to be found. The results are online at arXiv.org and will be published in two papers in Astronomy & Astrophysics and the Monthly Notices of the Royal Astronomical Society.
The new technique will eventually let astronomers measure the atmospheres of smaller planets around dimmer stars, says University of Florida exoplanet expert Eric Ford, a co-author of the paper describing HR 80606b.
"We can study these small planets, whether they're mini-Neptunes or super-Earths, and answer some questions about them now, rather than waiting for next generation of big space telescopes," he said.
These first two potassium-bearing planets are strikingly different. XO-2b is about the size of Jupiter, a little more than half Jupiter's mass, and revolves sedately around its star once every 2.6 Earth days. Sing and his colleagues found a clear signature of potassium gas as a stable component of the planet's atmosphere.
HD 80606b, on the other hand, is four times the mass of Jupiter and flies around its star in a crazy elliptical orbit that more closely resembles a comet's orbit than a planet's. The planet is flash heated as it comes close to its star, and then cools down again as it veers away. The atmospheric data suggests the potassium gas condenses into clouds when the planet is far from its star, and is being driven away from the planet by high-speed winds.
"They're seeing a signature of that atmosphere being essentially boiled away as it goes by the star," said exoplanet scientist Ruth Murray-Clay of Harvard, who was not involved in the new work. "It's pretty extreme."
Ultimately, astronomers would like to compare the amounts of several elements in the atmospheres of many different planets.
Seager and her colleagues predicted 10 years ago that potassium and sodium, both of which are solid on Earth, should be important gasses in most hot Jupiter atmospheres. But the first two planets to have their atmospheres analyzed showed only sodium.
The new discoveries "tell us that some of the basic models for hot Jupiter atmospheres that were proposed 10 years ago are pretty much right, in their gross characteristics," Murray-Clay said. "It gives us some confidence that we have some idea of what's going on, at least in the really hot ones."
The fact that two potassium-bearing planets were announced on the same day indicates astronomers are moving into a new stage in exoplanet discoveries, Seager adds.
"Until now, in exoplanets, we've had interesting things that scratch the surface. You might find one molecule in one planet, or one new planetary system," she said. "Now we're on this watershed where all of a sudden, you could study 100 transiting planets with this technique. We're moving into a much deeper level of work in exoplanets."
Images: 1) ESA w/adaptations by David Sing. 2) The Gran Telescopio Canarias./Pablo Bonet.
Posted: 31 Aug 2010 03:28 PM PDT
The discovery of nearly identical sea creatures on either side of a now solid Antarctic ice sheet — 1,500 miles wide and over a mile thick — points to an open ocean passage there as recently as 125,000 years ago.
The new evidence adds to geologic clues indicating the West Antarctic Ice Sheet has collapsed at least once in the last million years, and could do so again in a warmer climate. The complete collapse of the West Antarctic Ice Sheet would raise global sea level by 11 to 16 feet.
"The West Antarctic Ice Sheet can be considered the Achilles heel of Antarctica," biologist David Barnes of the West Antarctic Survey, lead author of the study, said in a press release. "Our research provides compelling evidence that a seaway stretching across West Antarctica could have opened up only if the ice sheet has collapsed in the past."
As part of the Census of Antarctic Marine Life, scientists were looking at the distribution of different species of bryozoans, small filter-feeders that are attached to the sea floor as adults (top image). They found that the populations of bryozoans were remarkably similar in two different seas separated by the ice sheet, the Weddell and the Ross.
"Because the larvae of these animals sink and this stage of their life is short — and the adult form anchors itself to the sea bed — it's very unlikely that they would have dispersed the long distances carried by ocean currents," Barnes said. "Our conclusion is that the colonization of both these regions is a signal that both seas were connected by a trans-Antarctic sea way in the recent past."
"This biological evidence is one of the novel ways that we can look for clues that help us reconstruct Antarctica's ice sheet history," Barnes said. The study appears in Global Biological Change.
The West Antarctic Ice Sheet is already considered to be highly vulnerable to climate change, but estimates of when it might collapse vary from a few hundred to a few thousand years.
Images: 1) Different types of bryozoans./West Antarctic Survey. 2) West Antarctic Survey.
Video: David Barnes
Posted: 31 Aug 2010 10:40 AM PDT
Explosive bursts normally seen only on the surface of the sun can now be captured in a 13-foot-long tube using lab-created plasmas and bursts of laser light.
Physicists have created a scaled-down model of solar eruptions called coronal mass ejections, which can wreak havoc on satellites and create beautiful northern-light displays on Earth. The new experiments suggest these eruptions are set off when gushes of charged particles flow into twisted loops of magnetic field that extend from the sun's upper atmosphere.
"You can do things in the lab that are absolutely impossible to do in space," said plasma physicist Walter Gekelman of the University of California, Los Angeles. Gekelman and UCLA physicist Shreekrishna Tripathi created miniature versions of enormous loops of solar matter called arched magnetic flux ropes. Their results are described in the Aug. 13 issue of Physical Review Letters.
These twisted magnetic ropes — also sometimes called coronal loops, prominences and filaments — can sit comfortably on the sun's surface for hours or days, transporting energy and matter from the solar surface to the outer atmosphere. But eventually they explode, shooting tons of charged particles out into space like a slingshot. These loopy time bombs have been photographed by observatories like the Solar and Heliospheric Observatory — but how they form, and what makes them collapse, is still unknown.
"Astronomical observations give you pictures of things. It's hard to deduce what's going on inside of it," said plasma physicist Steven Spangler of the University of Iowa, who was not involved in the new work. "So you'd really like to have a lab experiment to give you a scaled down version and bigger insights."
Some theoretical models have suggested the eruptions are triggered by jets of plasma, or gas that is so hot that all the electrons have been stripped away from their parent atoms. These plasma jets are injected directly from the sun into the roots of the magnetic arcs.
To test this idea, the team of physicists used a cylindrical vacuum chamber about 13 feet long and 3 feet wide to hold a background plasma. Earlier experiments used a spark to create a plasma arc that simulated the solar loops, but without a background plasma, those loops fell apart too quickly to be realistic.
"Those conditions are very very different than in a real flux rope," he said. "In the sun, there's plasma everywhere, not just in the flux rope."
Gekelman and Tripathi used two electromagnets to create an arched magnetic field, which produced a second plasma, analogous to the solar flux rope. They then fired two identical laser beams at carbon rods placed just behind the electromagnets, which shot two jets of carbon plasma directly into the ends of the flux rope.
These plasma jets created a destabilizing kink in the flux rope, making it erupt and send waves of energy rippling through the background plasma.
"They're completely stable until we eject flow into them," Gekelman said. "Then they go nuts."
The experiment doesn't absolutely prove plasma jets are responsible for coronal mass ejections, but "it's a hint and an indicator and should stimulate additional research," Spangler said. "We're beginning to get some hints into what are the crucial ingredients."
Image: 1) NASA/SOHO 2) S. Tripathi and W. Gekelman
Posted: 31 Aug 2010 08:20 AM PDT
The epic drilling to save the trapped Chilean miners has begun:
The miners have already survived underground longer than anyone else – they broke the 25 day record today – and will mostly like remain underground for at least another few months.
But this post is not about the miners, and their Dantesque plight. Instead, it's about our reaction to them, and the extraordinary outpouring of emotion that occurs whenever we can latch onto a set of identifiable victims. I wrote about the research of Paul Slovic in my book, How We Decide:
Of course, this is a deeply irrational reaction. We are much less interested in helping a victim – we only want to help the victim. (This bias is known as the identifiable victim effect, since it suggests that we react much more strongly when the victim can be specified.) Why do we this? Because human charity is ultimately rooted in our compassionate feelings, and not in some rational, utilitarian calculations. We are not Vulcans.
What's interesting, though, is that some people are much less vulnerable to the identifiable victim effect than others. (There are Spocks among us!) Consider this new paper led by James Friedrich, at Willamette University, which measured differences in "analytic processing" style among 120 undergraduates. (The test for this is a rather straightforward survey, which includes questions such as "I enjoy intellectual challenges" and "I believe in trusting my hunches".) Not surprisingly, people who tend toward analysis were also less likely to display the identifiable victim bias:
Just because the identifiable victim bias exists doesn't mean it's a mistake to move heaven and earth to save the miners. That impulse reflects one of the noblest human urges. But it does suggest that we should be more mindful of all the moments when we're not compassionate, when there are so many victims that no one can be identified. (As others have noted, the floods in Pakistan have received far less attention than warranted, in part because most of the stories focus on the vast scope of the disaster, and not on individual tragedies.) Our emotions might not understand such suffering, but the suffering goes on just the same. Auden said it best:
Posted: 31 Aug 2010 04:00 AM PDT
Posted: 30 Aug 2010 02:28 PM PDT
One of paleontology's most revered fossil sites now has a baby brother. Scientists have discovered a group of astonishing fossils high in the Canadian Rockies, just 40 kilometers from the famous Burgess Shale location.
Since its discovery in 1909, the Burgess Shale has yielded many thousands of fossils dating to 505 million years ago — a period often called "evolution's big bang," when animals were exploding in diverse body plans. These soft-bodied critters scurried around on the sea floor, then were buried in mudslides and exquisitely preserved.
Burgess fossils appear in several outcrops, all within about 60 kilometers of Field, British Columbia, and all occurring in shale deposits of the Stephen Formation that are 270 to 370 meters thick. Now, a team led by paleontologist Jean-Bernard Caron of the Royal Ontario Museum in Toronto reports finding Burgess-like fossils in the valley of the Stanley Glacier in Kootenay National Park, where a much thinner part of the Stephen Formation that ranges from 16 to 160 meters thick is exposed.
"This new locality adds to our knowledge of the environments where these organisms lived and died and thus adds important context," says Peter Allison, a geoscientist at Imperial College London.
About half of the animal groups found at Stanley Glacier, such as trilobites, are found at other Burgess sites in different abundances. But the creatures unearthed also include eight taxa previously unknown to science. They include an unnamed worm; Stanleycaris hirpex, a segmented shrimp-like critter known as an anomalocarid; and an arthropod with big eyes dangling on stalks from its head shield.
Until now, paleontologists had thought one reason the Burgess fossils were so well preserved was because they settled in thick deposits at the bottom of an ancient ocean protected by a submarine cliff. But the Stanley Glacier fossils weren't formed in the presence of such a cliff, suggesting that creatures can be fossilized in amazing detail in other environments.
"We consider it likely that future exploration and study will continue to yield new taxa from the 'thin' Stephen Formation, which is exposed over a broader area regionally than the 'thick' Stephen Formation," the researchers write.
New discoveries are still emerging from the classic Burgess localities. In May, after studying new Burgess fossils from one of the original sites, Caron and colleagues reported new details on a creature that may be one of the earliest known relatives of octopuses, squid and other cephalopods.
Image: Looking towards Stanley Glacier, site of the new fossil deposit. Flickr/judemat.
Posted: 30 Aug 2010 12:40 PM PDT
A stocky, two-clawed relative of Velociraptor and feathered dinosaurs has been discovered in Romania. Balaur bondoc,which means stocky dragon, is the first meat-eating dinosaur to be described that lived in Europe during the final 60 million years of the Age of Dinosaurs.
"Balaur might be one of the largest predators in this ecosystem because not even a big tooth has been found in Romania after over a hundred years of research," paleontologist Zoltan Csiki of the University of Bucharest in Romania said in a press release. Csiki is the lead researcher of the discovery announced Aug. 30 in Proceedings of the National Academy of Sciences.
The new dinosaur was about 6 to 7 feet long. It had functional big toes with large claws — presumably for slashing prey — in addition to a claw on the second toe that is typical of the group of dinosaurs. Its feet and legs were short and stocky, with bones fused together, and large muscle attachment areas on its pelvis, indicating the dinosaur was built for strength over speed. Its hands were atrophied, so Balaur likely used its feet rather than its hands to grasp prey.
"Its anatomy shows that it probably hunted in a different way than its less stocky relatives," said paleontologist Stephan Brusatte of Columbia University in a press release. "Compared to Velociraptor, Balaur was probably more of a kick boxer than a sprinter, and it might have been able to take down larger animals than itself, as many carnivores do today."
During the era that Balaur lived, sea levels were so high that much of Europe was under water and Romania was an island. Dinosaurs evolved there in relative isolation, with the occasional exchange of creatures between there and mainland Asia, says Csiki. Some of the other dinosaurs that have been found there from this time are dwarf sauropods the size of cows and tiny duck-billed dinosaurs.
According to Csiki, fragmentary remains of Balaur were already known for more than 10 years, but the morphology was so bizarre that scientists didn't know how to fit them together.
Images: 1) Csiki et al. 2) A sketch of Velociraptor mongoliensis, a feathered relative of B. bondoc that lived in Asia during the Late Cretaceous./PaleoPortfolio.
Posted: 30 Aug 2010 10:25 AM PDT
Ever since Einstein, physicists have been telling us that time – this steady tick-tock of the universe – is much weirder than we think. It doesn't flow in a single, linear direction, or beat like a steady metronome. Instead, it depends on all sorts of peculiar cosmi variables. We speed up, time slows down. (Fall into a black hole and time turns into a viscous sludge.) And there's nothing in the mathematical laws of physics that says time can only go forward. In theory, at least, the hands of your clock can tick in both directions.
But if time is so strange, then why does it seem so normal? Why don't we feel all the quantum weirdness? Psychologists and neuroscientists are now beginning to explore the phenomenology of time, beginning not with spacetime but with the fleshy brain. If our' sense of time is largely a cognitive illusion, then where does the illusion come from?
Let's begin by looking at this audacious experiment, led by David Eagleman of Baylor College of Medicine. (Eagleman is also a best-selling novelist – Sum is a brilliant riff on the possibility of an afterlife.) He was interested in why time seems to slow down when we're really scared. (His research was inspired by a childhood fall.) Of course, it's not easy to terrify subjects in a science lab, or to trick people into thinking that they're about to die. (It might also violate a few IRB rules.) And so Eagleman came up with an original experimental paradigm: SCAD jumping, which is often described as bungee jumping without the bungee. A subject is hoisted 150 up in the air and then dropped (hopefully) onto a big net. Jad and Robert of WNYC's Radiolab explain what happened next:
This is a deeply Proustian idea. It turns out that our sense of time is deeply entangled with memory, and that when we remember more – when we are sensitive to every madeleine and sip of limeflower tea – we can stretch time out, like a blanket. This suggests that the simplest way to extend our life, squeezing more experience out of this mortal coil, is to be more attentive, more sensitive to the everyday details of the world. The same logic should also apply to our vacations. If we want our time off to last longer, then we should skip the beach naps and instead cram our days full of new things, which we will notice and memorize.
Furthermore, the link between the perception of time and the density of memory can also work in the other direction, so that it's possible to increase our memory by speeding up our internal clock. In 1999, a team of psychologists at the University of Manchester demonstrated that it was possible to tweak our "pacemaker" by exposing people to a sequence of click-trains, or acoustic tones that arrive in rapid progression. It turns out that such click trains accelerate our internal clock – it beats a little bit faster – which means that everything else seems to take just a little longer. (Perhaps this is why, when companies put us on hold, they always play sluggish muzak – the adagio sounds might slow down our clock, thus making the frustrating experience of waiting on the phone pass more quickly.)
A new study, by the same Manchester lab, uses click trains to explore the implications of this accelerated tick-tock. It turns out that when our internal clock is ticking faster, we don't just perceive the external world as moving slower – we can actually remember more about it. In other words, our sense of time isn't just a perceptual illusion, but instead seems to regulate the pace of information processing in the brain. When it ticks faster, we can process more. It's like getting a faster set of microchips embedded in the cortex. (This suggests that we'd get better at executing very demanding tasks, such as making quarterback decisions in the pocket, or playing Rachmaninoff, if we listened to a series of fast clicks first.) Here's the abstract from the latest paper:
And this returns us to the SCAD jumping paradigm used by David Eagleman. Perhaps the feeling of terror is like a series of clicks, speeding up our clock. We think of time as a constant, but there is nothing constant about it. Even a fleeting feeling can change the pace of everything.
Image: A terrifying picture of a black hole sucking in spacetime.
|You are subscribed to email updates from Johnus Morphopalus's Facebook notes |
To stop receiving these emails, you may unsubscribe now.
|Email delivery powered by Google|
|Google Inc., 20 West Kinzie, Chicago IL USA 60610|