Wednesday 3 November 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Rare Dead Quasar Found in Nearby Galaxy

Posted: 02 Nov 2010 02:16 PM PDT

One of the universe's brightest lights, a black hole-driven quasar in a nearby galaxy, recently shut off like a snuffed candle.

New observations of a bizarre cloud of glowing gas, and a nearby galaxy that illuminates it, show that the galaxy's central light went dim sometime in the last 70,000 years. The finding could reveal how supermassive black holes help galaxies grow and evolve.

"This is the best view we will ever have of the host galaxy of a quasar," said astrophysicist Kevin Schawinski of Yale University, lead author of a paper published online Oct. 26 in Astrophysical Journal Letters and cofounder of the crowdsourced space science project Galaxy Zoo. "It's the nearest one to us, and the quasar is dead."

Quasars are ravenous, supermassive black holes that lurk at the centers of some galaxies and devour gas and dust from a surrounding disk. As the gas falls into the black hole, a process astronomers call accretion, friction heats the gas until it glows white-hot.

"Accretion transforms the darkest objects in the universe into the brightest," said black hole expert Chris Done of the University of Durham in the U.K., who was not involved in the new study. "It's like the final scream before it disappears forever below the event horizon."

Astronomers have long suspected that energy from quasars can help galaxies grow, a notion supported by the fact that bigger galaxies tend to have bigger central black holes. But until now, evolving galaxies have been impossible to observe.

 

A new clue comes from Hanny's Voorwerp, a weird cloud of glowing green gas found in Galaxy Zoo's archival telescope data in 2007. The Voorwerp (Dutch for "object" ) was thought to be lit up by a nearby quasar zapping it with a floodlight-like jet of ionizing radiation.

But there was no nearby quasar to be found. The closest object was a wimpy, dim galaxy called IC 2497 between 45,000 and 70,000 light-years away from the Voorwerp. Both objects are about 730 million light-years from Earth, "which cosmologically speaking is our backyard," Schawinski said.

There were two possible explanations for the missing quasar. Either there's so much gas and dust between Earth and the galaxy that the floodlight looks like a flashlight to us, but not to the Voorwerp, or the quasar died sometime between when its light hit the Voorwerp and now.

To test the first idea, Schawinski and colleagues observed the galaxy with two space telescopes, the Suzaku X-ray Telescope and the XMM-Newton X-ray observatory. These telescopes detect high-energy X-rays that would penetrate even the thickest clouds of dust.

The team did see a few X-rays, but it was "a really weak, puny little source," Schawinski said.

"This source is way way way too weak to light up the Voorwerp," he said. "It's like trying to light up your house with an LED. It's just not enough."

As it appears today, the quasar is 100 to 10,000 times dimmer than whatever lit up the Voorwerp, Schawinski and colleagues concluded. The quasar must have shut down sometime in the last 45,000 to 70,000 years, while its light was still traveling to the Voorwerp, and left the cloud as a ghostly echo of the dead quasar's former brilliance.

Because the quasar switched off so quickly, the accretion disk surrounding the black hole must have been relatively small, Done says. That's consistent with some models of how black holes gobble up their surroundings.

"Those models are quite hard to test," Done said. "This might tell us is that our ideas about accretion do actually work. I'm quite excited about it."

The quasar corpse also provides a unique laboratory for studying how galaxies evolve shortly after their central engines quiet down.

"It's certainly giving us a view of a very particular phase of the evolution of quasars, and one that we can't normally study," Done said.

The discovery would never have happened if not for Galaxy Zoo, Schawinski notes.

"We would have never found the nearest quasar to us, this system that will ultimately teach us so much about black holes and galaxies and how they evolve together, if it wasn't for citizen science and the internet," he said. "It's so much cooler than anything we could have imagined."

Image: WIYN/William Keel/Anna Manning

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High Oxygen Levels Spawn Monster Dragonflies

Posted: 02 Nov 2010 02:14 PM PDT

Biologists have grown super-size dragonflies that are 15 percent larger than normal by raising the insects, from start to finish, in chambers emulating Earth's oxygen conditions 300 million years ago.

The research, presented Nov. 1 at the Geophysical Society of America's annual meeting in Denver, Colorado, provides more support to the idea that big ancient animals and high-oxygen concentrations weren't coincidental. It may also offer an instrument to help gauge Earth's ancient atmospheric conditions.

"No one has been successful growing dragonflies under controlled laboratory conditions before, at least to my knowledge," said paleobiologist John VandenBrooks of Arizona State University, leader of the work. "This has allowed us to ask the question, 'how have oxygen levels through time influenced the evolution of insects?'"

During the Paleozoic era, around 300 million years ago, huge dragonflies zipped around with wingspans stretching more than two and a half feet, dwarfing modern relatives. Back then, however, the planet's atmosphere had roughly 50 percent more oxygen than today.

To explore the effects of ancient oxygen levels, VandenBrooks' team raised 11 other "living fossils," including beetles and cockroaches, in three habitats with different oxygen concentrations — one at the late Paleozoic's 31 percent oxygen level, another at today's 21 percent level and the third at 12 percent from 240 million years ago (Earth's lowest oxygen level since complex life exploded onto the scene half a billion years ago).

They found that dragonflies and beetles grew faster, as well as bigger, in a high-oxygen environment, while cockroaches grew slower and remained the same size. All but two bug species grew smaller than normal at low concentrations of oxygen.

Measurements of insect breathing-tube volume from the experiment could be correlated with that of insects trapped in amber, VandenBrooks said, providing a solid tool to determine oxygen levels in poorly understood eras.

"We started out with insect physiology to understand the fossil record better, in light of data from modern species," he said. "Then we realized we might have a biological tool to estimate ancient oxygen levels — a proxy — using that physiology in specimens trapped in amber."

 

Dragonflies are born as water-loving nymphs and spend about half a year wolfing down small worms, crustaceans and, eventually, larger prey such as guppy fish. When adults emerge as speedy terrestrial fliers, they begin breathing through a network of tracheal air tubes and live only for a couple of weeks.

"It wasn't quick, but it paid off," VandenBrooks said of raising the critters in the lab, adding that 225 nymphs (75 per atmospheric habitat) had to be hand-fed worms and guppies every day for almost half a year.

After the dragonflies and other bugs grew up, the researchers measured their breathing-tube volumes. They discovered that high oxygen concentrations lowered tracheal volume, while low oxygen concentrations boosted it. VandenBrooks said tracheal volume may directly affect dragonfly body size.

"As you become a larger insect, more of your body is taken up by tracheal tubes. Eventually you reach a limit to how big you can be," VandenBrooks said. "The more oxygen that is available, the smaller that system needs to be and the bigger you can grow."

Beetles also grew proportionally larger but, conversely, cockroaches didn't swell to monsters like dragonflies did in rich oxygen levels. Instead, they remained the same size and developed more slowly. Their tracheal volume, however, still decreased along with most of the other bugs.

"We're not sure why this happened, but we might be able to use tracheal volume in amber fossils to find out what oxygen concentrations were during some contentious periods in history," VandenBrooks said, noting oxygen levels around 300 million years ago are better known than from 120 to 65 million years ago, a period with "conflicting and poorly resolved" oxygen models.

"One model out there says levels were lower than now, another says higher-than-present levels," he said. "We need a good proxy to estimate historic conditions. Amber fossils are promising if we can more tightly correlate breathing-tube volume to oxygen."

VandenBrooks said he'd like to "take a more in-depth look at the fossil record and expand forward to the present and backward to the past" to see if amber is a viable proxy. In addition, he wants to repeat the oxygen-level experiment focusing more tightly on dragonfly behavior.

"We want to know how it affects their metabolism," VandenBrooks said. "How does it affect their ability to perform? Their speed? Their efficiency? I'd love to know these things."

Images: 1) Flickr/Al Power. 2) Micrograph of a modern honey bee's internal tracheal tubes, the means by which all insects exchange oxygen with their body's tissues./USDA 3) A dragonfly raised in one of VandenBrooks' hyperoxic habitats./John VandenBrooks.

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Arctic Lake Yields Planet’s Most Continuous Record of Ancient Climate

Posted: 02 Nov 2010 10:39 AM PDT

DENVER — It took the better part of a decade, $10 million, and help from the guys who build ice roads for Canadian truckers. But scientists now have the most continuous record of ancient climate ever extracted from the terrestrial Arctic.

What's more, the record — cored through sediment layers at the bottom of a lake in northeastern Siberia — also illuminates what happened when a big meteorite smashed into the spot 3.6 million years ago, when the ground was warmer and forested as opposed to the barren tundra it is today. Water filled the resulting crater and formed Lake El'gygytgyn (pronounced EL-gih-git-gin).

"We're really pleased that we have a complete record of that entire time period," said Julie Brigham-Grette, a geologist at the University of Massachusetts at Amherst and one of the project's leaders. She described the findings in Denver on October 31 at the annual meeting of the Geological Society of America.

Analysis of the lake cores is revealing details of how the Arctic landscape warmed and cooled over the past several million years, she said. Comparing similar data from the Arctic Ocean and Antarctica can show how the two polar regions — which are more sensitive to climate change than temperate or tropical latitudes — react differently to changing temperatures.

"The sheer logistics prevented anyone from doing this before," said Brigham-Grette.

 

Lake El'gygytgyn lies 100 kilometers north of the Arctic Circle and 360 kilometers from the nearest inhabited town: Pevek, Russia. The 12-kilometer-wide lake is too windy and rough to be drilled from a floating rig in the summer, so the researchers decided to drill in the winter from an ice platform.

To get there, the team had to ship camp materials and a drill rig to Pevek, then use helicopters or trucks running on an ice road that ended 90 kilometers short of the lake. For the final 90 kilometers equipment had to be hauled with bulldozers through the snow.

After all that, the team had to artificially thicken the lake ice by drilling a small hole and pumping water to the top to freeze again, to get the ice to the 2 meters of thickness that could support the weight of the drill rig.

The lake is deep enough to not freeze all the way to the bottom in winter, meaning it is a sediment trap whose layers of mud contain pollen and other indicators of what the environment was like at the time the material settled. Other lakes in the far north have frozen solid many times and thus don't contain such a detailed record.

This unique record along with the lake's high latitude make the work important scientifically, says Yarrow Axford, a paleoclimate expert at Northwestern University in Evanston, Ill., who is not involved in the project.

At the time the kilometer-wide meteorite hit, temperatures were probably 10 to 14 degrees Celsius warmer than today, Brigham-Grette said. The impact vaporized much of the silica-rich rock, turning it into a jumble known as breccia with fractured quartz grains and other particles melted by the impact's heat, said team member Christian Koeberl of the University of Vienna.

The core holds no tiny fossils or pollen in the 15 meters just above the layer that marks the meteorite impact, Brigham-Grette reported at the conference — possibly because the searing heat zapped anything that would otherwise have been preserved. At least ten different layers of volcanic debris, scattered throughout the core, reflect eruptions of volcanoes on the Kamchatka peninsula to the south, she said.

Brigham-Grette hopes to compare the cores to others from the same time period, like those drilled in Lake Baikal — also in Siberia but at 54 degrees north rather than 67 degrees — and others taken from the underwater Lomonosov Ridge in the Arctic Ocean.

Images: 1) Lake El'gygytgyn, as seen from space. Jesse Allen/NASA/GSFC/METI/ERSDAC/JAROS/ASTER. 2) Lake El'gygytgyn drilling camp in the high Arctic./NSF. 3) Drilling of the sediment core./NSF.

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Cutest Book Ever: ZooBorns Internet Craze Moves to Print

Posted: 02 Nov 2010 10:07 AM PDT

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Warning: The images in this gallery are dangerously, addictively cute. Once you have seen them, you'll want to see more, and more. And more. And you may never finish what you were working on before you saw them. But it's probably too late for you, anyway, because you've already seen the baby ocelot, so never mind.

If you weren't already aware of this thing called ZooBorns, then I'm sorry for doing this to you. Also, you're welcome, because it's the cutest thing ever on the internet.

And now you can't escape it, even when you are away from the internet, because the evil geniuses behind the ZooBorns website have just published two books of strangely, wonderfully, painfully cute baby zoo animals that you can take with you everywhere (I've already proven this with my review copies).

While you are waiting for yours to arrive, you can try to get by on the baby aardvark, gorilla, red pandas and more in this gallery, visit ZooBorns.com and hear what the authors, Andrew Bleiman and Chris Eastland had to say for themselves in the interview with Wired.com on the following pages.

Wired.com: Do you have a favorite ZooBorn?

Eastland: I'm your run-of-the-mill, crazy cat lady, just 30 years old and male. If I have to choose, it would probably be the Connecticut Beardsley Zoo's ocelot kitten, aka the Miracle Kitten (above). It got its name since it was only the third ocelot ever born via in vitro fertilization.

Above: Ocelot Kitten

Connecticut's Beardsley Zoo

Image: Shannon Calvert

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Baby Dolphin Survival Depends on Mom’s Friends

Posted: 02 Nov 2010 08:45 AM PDT

For dolphin mothers, successful parenting is as much a matter of having good friends as it is good genes.

The findings underscore the importance of community to dolphin life, and perhaps to animals in general — something that's intuitively appreciated, but hasn't been directly compared to genetic fitness in a wild mammal population.

Some studies, including research on captive chimpanzees, have linked heredity to the survival rates of young animals. Research on wild horses has connected offspring survival to maternal sociality. But researchers had not yet compared nature and nurture directly.

"In wild populations, genetic heritability and the social components of fitness have not yet been examined together," wrote researchers led by University of New South Wales biologists Celine Frère and William Sherwin in a paper published Nov. 1 in the Proceedings of the National Academies of Science.

 

For 25 years, the researchers have made detailed observations of bottlenose dolphins in the eastern gulf of Australia's Shark Bay. That one-of-a-kind dataset allowed them to chart the relatedness of dolphin moms and map their habits of social association, then correlate these patterns to how well their offspring survived childhood.

As would be expected, calves born to moms from reproductively successful families tended to do well. But for dolphin moms from less-fit families, that lack of a pedigree was offset if they tended to hang out with successful moms. The researchers' analysis suggested that keeping good company was just as important — even, at times, more important — than coming from good stock.

That society could have such importance isn't shocking: Dolphins are extremely intelligent, with complex communities and powers of communication that some researchers consider comparable to language. (It's also in Shark Bay that evidence of dolphin tool use was famously found.) Nevertheless, "we can only speculate" as to the details of how females help each other, wrote Sherwin in an e-mail.

Close friends might help protect female dolphins from unwanted male attention, reducing inbreeding and resulting health problems, wrote Sherwin. Defense could also be important, especially during birth and early nursing stages. "The dolphin population we studied is in Shark Bay," he wrote.

Image: Flickr, Steve Jurvetson.

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Citation: "Social and genetic interactions drive fitness variation in a free-living dolphin population." By Celine H. Frère, Michael Krützen, Janet Mann, Richard C. Connor, Lars Bejder, and William B. Sherwin. Proceedings of the National Academy of Sciences, Vol. 107 No. 44, November 1, 2010.

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