Thursday, 27 January 2011

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Hubble Finds Galaxy Beyond Key Benchmark

Posted: 26 Jan 2011 12:23 PM PST

A candidate for the most-distant galaxy ever spotted has shown up in an image from the Hubble Space Telescope. The faint fuzzy blob, whose light reached Hubble from just 480 million years after the Big Bang, could be a landmark in galaxy detection.

"It's amazing that we finally believe that we have observed something at this epoch," said astronomer Rychard Bowens, now of Leiden University in the Netherlands, lead author of a paper to appear in the Jan. 27 Nature. "It's like breaking the 4-minute mile in running. It's had a little bit of awe."

The new galaxy, called UDFj-39546284, is about 13.2 billion light-years away. The last record holder was confirmed in October 2010 at 13.1 billion light-years away. Both galaxies were spotted in a Hubble image called the Ultra Deep Field, which captures 10,000 galaxies in the universe's earliest millennia.

Although the new galaxy is not, in astronomical terms, much farther away than the next-most-distant galaxy, it may be the first to hit "redshift 10," a distance milestone that astronomers have been aiming at for decades.

The term comes from the technique used by astronomers to estimate the distance from Earth of faraway cosmic objects. Because the universe is expanding, distant stars and galaxies appear to be zooming away from us. As galaxies recede, the wavelength of their emitted light stretches out, making them appear more and more red.

Measuring a galaxy's redshift tells how long ago its light was emitted. Multiply time by the speed of light, and distance can be calculated.

"Redshift 10 has been this gauntlet, this quest. A lot of people have attempted to get there," Bouwens said. "I think this is the first time that it's actually plausibly at this epoch."


This galaxy is dimmer than the previous oldest galaxy, in keeping with a pattern: As astronomers look back through time, galaxies are fainter. They have fewer young stars, which burn especially bright.

Run from the beginning, though, and they're getting brighter. The Ultra Deep Field image seems have caught the universe in a growth spurt.

"Galaxies are like human beings," growing fastest when they're young, Bouwens said.

To make the Ultra Deep Field image, Hubble used the new Wide Field Planetary Camera 3, part of a 2009 upgrade, to stare for 87 hours at a patch of sky roughly equivalent to what's covered by a postage stamp, folded into quarters and held at arm's length.

"We wouldn't even be able to come close without this instrument," Bouwens said.

Unfortunately, this galaxy runs right up against Hubble's detection limit. If the galaxy were farther away, it would be too red for Hubble to see at all.

"Our object is about as good as it's going to get for some time," Bouwens said. "It'll be hard to find more-compelling evidence for a distant object than what we've done."

Despite Bouwen's confidence, some astronomers are still skeptical.

"It was selected using a very rough technique, and it's plausible that it's at redshift 10, but it could be at lower redshift," said astronomer Naveen Reddy of the National Optical Astronomy Observatory in Arizona, who was not involved in the new work. "More work needs to be done."

Bouwens and his colleagues admit that they can't be 100 percent certain that their galaxy is actually at redshift 10, or that it's really there at all.

"There's been a grand tradition of people crying wolf about redshift-10 galaxies," said Bouwens. "There's some worry that it could just be noise. That would be really embarrassing."

To find galaxies at distances beyond redshift 10, astronomers will have to wait for the James Webb Space Telescope, the proposed successor to Hubble. In theory, the Webb could see out to redshift 35 — if there's anything there to see.

The very early universe was a hot soup of neutral hydrogen atoms. Hydrogen absorbs light at most wavelengths, so this era of the universe should be an opaque fog.

But high-energy radiation from the first stars stripped the hydrogen atoms of their electrons, turning the universe transparent in an epoch astronomers call reionization.

Observations of galaxies like UDFj-39546284 suggest that the stars we can see wouldn't be powerful enough to turn the universe transparent. There must be smaller, fainter galaxies hiding in the data.

Images: NASA, ESA, Garth Illingworth (University of California Santa Cruz) and Rychard Bouwens (University of California Santa Cruz and Leiden University) and the HUDF09 Team.

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Carnivorous Plants Eat Poop From Tiny Bats

Posted: 26 Jan 2011 07:37 AM PST

By Mark Brown, Wired UK

In a bizarre example of a symbiotic relationship, tiny bats in Borneo have been found using a carnivorous plant as a toilet, feeding the pitcher plant with their droppings, while they safely roost in the plant's traps.

Ulmar Grafe, an associate professor at the Universiti Brunei Darussalam, was researching the pitcher plant — a giant, carnivorous vine with deep, pitfall cups that are used to trap prey — for a study published in Biology Letters. Grafe wanted to find out how the pitcher managed to find the nitrogen needed to survive in the nutrient-poor peat swamps of Borneo in southeast Asia.

His team found Hardwicke's woolly bat — a tiny, four gram animal no bigger than a car key — consistently sleeping in the carnivorous plant's traps during the day. Sometimes alone, sometimes with a partner or with a child. Roosting on top of each other, two or three bats could snugly fit in the pitchers.


But the plant wasn't getting its nutrients by munching on the tiny bats. In fact, the plant has adapted to stop the winged critters from tumbling down into the bottom of the trap and drowning in the digestive fluid. The vine's pitchers have a tapered shape and an unusually low amount of fluid, to stop the bats accidentally becoming dinner. That also prevents the monkeys from eating the insects that the plant catches.

Instead, the plants get their nutrients from the bat droppings, absorbing the feces and urine for nitrogen.

It's only the second time that researchers have documented a case of a mammal using a carnivorous plant as a natural toilet. In 2009, researchers found tree shrews defecating into another type of plant. But the shrews didn't seem to use the plant in return, exhibiting a nonchalant poop-and-go attitude.

The bats, however, have a mutualistic link with the plant, choosing its cozy, dry cavity and lack of blood-sucking ectoparasites as a perfect place to roost.

Image: Ulmar Grafe

Source: Wired UK

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First Earth-Orbiting Solar Sail Unexpectedly Unfurls

Posted: 26 Jan 2011 04:00 AM PST

After a month and a half trapped in its mothership, NASA's NanoSail-D spacecraft has finally unfurled the first solar sail to circle the Earth.

Solar sails, gossamer-thin sheets that feel the pressure of the solar wind, have been suggested as a best hope for propelling spacecraft between the stars. They're the only known method of space travel that doesn't require carrying heavy fuel on the journey.

But solar sails have had a checkered history. Only one has ever actually worked: the Japanese IKAROS spacecraft, which launched in 2009 and flew by Venus in 2010.

NanoSail-D looked set to be another heartbreak. It launched aboard the Fastsat (Fast, Affordable Science and Technology SATellite) in November 2010, along with five other experiments. A spring was supposed to push the breadbox-sized NanoSail-D probe into its own orbit. But when the time came, the probe got stuck.


To everyone's surprise, NanoSail-D spontaneously ejected itself on Jan. 17. Engineers still don't entirely know why.

Three days later, on Jan. 20 at 10 p.m. EST, the free-flying spacecraft unfurled its silvery sail. An onboard timer activated a wire burner, which cut a 50-pound fishing line holding the spacecraft's panels closed. Within seconds, the thin polymer sheet unrolled into a sail 10 square meters in area.

"This is tremendous news and the first time NASA has deployed a solar sail in low-Earth orbit," said NASA engineer Dean Alhorn in a press release. "To get to this point is an incredible accomplishment for our small team."

The successful unfurling was confirmed from the ground with the help of amateur ham radio enthusiasts, who continue to track NanoSail-D.

Rather than soar between the stars, NanoSail-D was designed to help clean up space junk. As the sail orbits, it skims the top of the atmosphere, experiencing enough drag to pull the sail back to Earth in 70 to 120 days.

If it works to clean up the clutter in low-Earth orbit, drag sails might become a standard issue on future satellites, pulling them out of the sky to disintegrate harmlessly in the atmosphere.

Skywatchers should be able to track and photograph NanoSail-D before it returns to Earth. Stay tuned for details.

Via Science@NASA

Image: NASA

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