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Planets can get twice as close to their suns without evaporating

Thu, 06 Dec 2007 07:33:00 -0500

A new computer simulation has suggested that giant gas planets can get twice as close to their stars as Mercury is to the Sun without evaporating.

Many gas giants have been found very close to their parent stars – a handful even lie less than 6% of Mercury's distance from the Sun. But it has never been clear just how close planets could get without heating up so much that their atmospheres would start escaping or "evaporating" into space.

The outermost layer of a planet's atmosphere is where the action is as far as evaporation is concerned. The star blasts this layer with ultraviolet light and X-rays, which heat it up. The atmosphere can stay cool and avoid evaporating if it can radiate enough energy back into space in the form of infrared light.

To see how the balance between these two effects shifted with distance from the star, Tommi Koskinen of University College London, and his team, created a 3D computer simulation of the upper atmosphere of a planet with the mass of Jupiter orbiting a Sun-like star. They found that evaporation did not occur until the planet was within about 40% of Mercury's distance from the Sun – about twice as close as a previous estimate.

The difference comes from taking into account a natural coolant called H3+, an ion made of three hydrogen atoms joined together that is found in the atmosphere of Jupiter and other gas giant planets. H3+ is a very efficient radiator of infrared light, so it helps the upper atmosphere stay cool.

Without the H3+, the upper atmosphere jumps from about 3000° Celsius to more than 20,000° C, hot enough for it to start boiling away into space.

"Even so, planets at that distance would lose material only very slowly, allowing them to survive for many billions of years," Koskinen told New Scientist.

The team said that their results agree with observations of a planet with about 70% the mass of Jupiter called HD 209458b, which orbits its star at about 12% of Mercury's distance from the Sun, well within the evaporation zone.

Researchers have calculated that even HD 209458b should last for many billions of years at the rate that it is losing matter, with all the known planets around other stars appear to be capable of surviving where they are for billions of years.

"They all look very stable and many of them are very close in to their star," said Koskinen. "But there's a lot of uncertainty about these things and we shouldn't say anything too definite at this point," he added. (ANI)

The Ã¢â‚¬Ëœgreat, great, great, great grandfatherÃ¢â‚¬â„¢ of modern kangaroos didnÃ¢â‚¬â„¢t hop

Thu, 06 Dec 2007 07:33:00 -0500

Kangaroos were not hopping creatures always, for a 25 million-year-old fossil has revealed that one of the earliest kangaroos did not hop on its hind feet like its modern relatives, but galloped across the land on all fours.

The skeleton, dug up in northern Queensland in 1997, also showed that this ancient kangaroo, which was about the size of a small dog, had canine fangs that were possibly used to fend off competitors or attract mates.

The near-complete skeleton represents a new species called Nambaroo gillespieae, one of the earliest known predecessors to the modern animal.

The La Trobe University palaeontologist Ben Kear, part of an Australian team that analysed the bones, said that the Nambaroo had big, muscly forearms that showed it galloped or bounded like a brushtail possum.

He added that the prehistoric kangaroo also had opposable big-toes and flexible feet, indicating that it had some climbing skills, like today's tree kangaroos.

Nambaroo lived in a dense, forest environment, which suggests a diet of fruit and fungi.

"This is really the great, great, great, great grandfather of modern kangaroos,'' The Age quoted Dr Kear, as saying.

"You've got this primitive kangaroo, imagine it's climbing low branches, bounding around the forest floor, eating fungi, eating fallen fruit. It's very different to what we would imagine from your average kangaroo... that you see today,” he added.

Dr Kear further explained that the nambaroo skeleton would facilitate scientists learn more about how climate change had an effect on the evolution of kangaroos over millions of years.

"Looking at a skeleton like this is the Rosetta Stone, it's the quintessential fossil that will give you the beginning of the whole kangaroo radiation,'' Dr Kear said.

The findings are published in the latest issue of the Journal of Paleontology. (ANI)

First stars in the Universe might have been "dark stars" with no twinkle

Thu, 06 Dec 2007 07:33:00 -0500

The first stars in the beginning of the universe might have been invisible "dark stars", which were powered by the presence of dark matter, a new study has indicated.

The new study, which point to these objects as being the first stars in the universe, was conducted by astrophysicist Paolo Gondolo, associate professor of physics at the University of Utah.

It was also calculated by the study that how the birth of the first stars almost 13 billion years ago might have been influenced by the presence of dark matter, which is the unseen, yet-unidentified stuff that scientists believe makes up most matter in the universe and is even helping it to expand further.

Scientists generally believe that the universe came into being 13 billion years ago in a sudden expansion or "inflation" of time and space known as the "big bang."

The afterglow of that explosion, known as the cosmic microwave background radiation, developed small fluctuations in temperature that caused some of the earliest matter to begin clumping together, a process accelerated by gravity and that produced the first stars and galaxies. The matter was mostly dark matter but also included normal matter in the form of hydrogen and helium gas.

Scientists know dark matter exists because galaxies rotate faster than can be explained by the visible matter within them. Also, observations by satellites, balloons and telescopes have led to the estimate that all the visible matter represents only 4 percent of the universe, which also is made of 23 percent dark matter and 73 percent "dark energy".

For the new study about the "dark stars", the astrophysicists calculated how dark matter would have affected the temperature and density of gas that clumped together to form the first stars.

The findings suggest that dark matter neutralinos interacted so they "annihilated" each other, producing subatomic particles called quarks and their antimatter counterparts, antiquarks. That generated heat. As a proto-stellar cloud of hydrogen and helium tried to cool and shrink, the dark matter would keep it hot and large, preventing fusion from igniting the star.

"The heating can counteract the cooling, and so the star stops contracting for a while, forming a dark star some 80 million to 100 million years after the big bang," said Gondolo. "This is our main result," he added.

The study also points out that dark stars have some important implications for astrophysics.

For example, their possible existence could aid the search to find and identify dark matter. That is because gamma rays, neutrinos and antimatter have characteristic energy signatures if they come from dark matter.

Also, they could improve understanding of how heavy elements formed. The first stars supposedly were the cradle of elements as heavy or heavier than carbon, producing them via nuclear fusion. But if dark stars existed and did not later evolve into normal stars, they didn't make carbon. "Maybe carbon
came from other stars - perhaps conventional stars that formed where there was no dark matter nearby," said Gondolo.

The existence of dark stars might also explain why black holes formed much faster than expected. The new study says that black holes existed only a few hundred million years after the big bang, yet current theories say they took longer to form. "These dark stars may help. They could collapse into black holes very early because they are very short-lived and formed when the universe was young, at least in one scenario," said Gondolo.

According to Gondolo, dark stars would contain mostly normal matter, mostly in the form of hydrogen molecules and helium. "But they would be vastly larger and fluffier than the sun and other stars. They would have glowed infrared, which is heat," he said.

"They are much bigger than the sun, with diameters ranging from about 4 astronomical units (372 million miles, or four times the average distance between the sun and Earth) to 2,000 astronomical units, that is big enough to swallow 15,000 solar systems like our own," said Gondolo.

It is conceivable that gigantic dark stars may exist today, and although they do not emit visible light, they could be detected because they should spew gamma rays, neutrinos and antimatter and be associated with clouds of cold, molecular hydrogen gas that normally wouldn't harbor such energetic particles. (ANI)

Damming the Red Sea might generate 50 gigawatts of electrical power for the Middle East

Thu, 06 Dec 2007 07:33:00 -0500

A new report has suggested that building a dam around the Red Sea could solve the growing energy demands of millions of people in the Middle East and alleviate some of the region's tensions pertaining to oil supplies through hydroelectric power.

If such a massive engineering project does take place, it would be able to release 50 gigawatts of electrical power.

According to geochemical engineer Schuiling, a dam could be used to stem the inflow of seawater into the highly evaporative Red Sea with the potential of generating 50 gigawatts of power. By comparison, the Palo Verde nuclear power plant, the largest nuclear station in the US has an output of just 3.2 gigawatts.

Though the size of the hypothetical dam would be enormous, it might be possible in the future to build dams large enough to separate a body of water as large as the Red Sea.

A major advantage of building such a dam would be that it will provide enormous reductions in greenhouse gas emissions as well as offering a viable, sustainable alternative to fossil fuels for future generations.

But the huge dam around the Red Sea would have its share of negative aspects as well.

"Such a project will dramatically affect the region's economy, political situation and ecology, and their effects may be felt well beyond the physical and political limits of the project," said Schuiling.

Schuiling and his colleagues point out that the cost and timescales involved in creating such a hydroelectric facility are way beyond normal economical considerations. It is inevitable that such a macro-engineering project will cause massive devastation of existing ecologies .

So, the ethical and environmental dilemmas are on an international scale, while the impact on ecology, tourism, fisheries, transport and other areas could have effects globally.

The researchers point out that the precautionary principle cannot be applied in making a decision regarding the damming of the Red Sea.

"If the countries around the Red Sea decide in favor of the macro-project, it is their responsibility to limit the negative consequences as much as possible," they conclude.

An example of such a macro-scale engineering project is already planned for the Strait of Hormuz at the entrance of the Persian Gulf. This seawater barrier will exploit the evaporative cycle and influx of seawater to generate vast quantities of electricity. (ANI)

Volcanic 'face' on the Moon developed over 4 billion years ago

Thu, 06 Dec 2007 02:46:00 -0500

A scientist of Indian origin is part of a new study based on a moon rock, which indicates that volcanoes, that are visible from Earth and resemble a face on the surface, developed on the moon soon after its formation, leading to new information about how planets develop in their early stages.

The 30-pound (13.5-kilogram) moon rock was found in the Kalahari Desert in Botswana in 1999.

"It seems like it came upon Earth relatively recently, unlike many lunar meteorites," team member Mahesh Anand of Open University in Milton Keynes, England, told National Geographic News.

"The meteorite landed on Earth about 200 to 300 years ago," said Anand. "It was probably blasted free from the moon when an asteroid hit the lunar surface," he added.

But the Kalahari meteorite is made of basalt, a common rock that forms from cooling magma, that is a telltale sign of volcanic activity.

According to Anand, the age of the rock suggested that volcanoes had already begun erupting just 150 million years after the moon's creation.

Earlier studies—based on rocks collected from the moon's surface during the Apollo missions between 1969 and 1972—suggested that the bulk of the moon's volcanic activity occurred after 3.9 billion years ago.

"Apollo-era research suggested that it took a long time for the moon's volcanoes to erupt," said Anand.

But the researchers came up with the new theory about volcanic formation on the moon after examining small grains of two phosphate-containing minerals—apatite and merrillite—inside the rock.

Once magma solidifies, it becomes closed like a time capsule, and its radioactive uranium begins to split into other elements. Measuring the ratios of these elements reveals the rock's age.

Using this process, it was proved that the Kalahari meteorite is made of magma that solidified 4.35 billion years ago, soon after the moon formed.

"So volcanism on the moon had started much earlier than we had thought," said Anand.

The new research also sheds rare light on the earliest stages of planet formation, which has largely been lost on Earth, where plate tectonics continually recycle the crust, sucking continents into the planet's interior and melting the rocks.

Because of this, even tiny bits of rock from early Earth are extremely scarce.

But since the moon is much smaller, it cooled quickly and never developed plate tectonics. Many of its ancient rocks are still on or near the surface.

"The beauty of the moon is that it preserves almost the entire history of the solar system," said Anand.

"The work is important because we are looking at the moon for a snapshot of what the early Earth was like," said Irene Antonenko, a geologist with Geosoft, a geology software company based in Toronto, Canada. (ANI)

Kids close to their parents are more independent as adults

Thu, 06 Dec 2007 02:36:00 -0500

A close relationship with parents is often viewed as a sign of dependence, but a new research has found that young adults who share a strong bond with their parents exhibit greater independence in their personal lives than those who have a distant relationship.

Dr. Irit Yanir from the University of Haifa evaluated how a parent-child relationship is connected to one's ability to fulfill society's expectations in terms of settling down and establishing an intimate relationship.

As part of the study, she conducted in-depth interviews with psychologists, parents and young adults between the ages of 23-27. An additional 100 families (father, mother and child) completed 300 surveys.

Dr. Yanir believes a close relationship with parents is one in which kids talk with their parents often and regularly spend time together such as eating meals together and one in which a child feels comfortable sharing his thoughts and experiences with his parents.

She differentiated between connectedness and relationship-orientation, which refers to the youth's need to satisfy his parents and fulfill their expectations. A connected offspring may share with his parents and solicit their advice, and still make independent choices and decisions.

"An independent young adult is one who exhibits independence not only in his day-to-day life but also in the emotional sphere, and who makes his way in life with emotional and intellectual autonomy," she said.

A close relationship is often viewed as a sign of dependence but the research results revealed that those with close relationships with their parents were more financially self-sufficient, more independent in their day-to-day lives, professionally stable, felt more mature and were more likely to be involved in a stable intimate relationship.

Those who maintained distant relationship with their parents and tended to make choices out of a need to rebel against their parents' expectations were less independent into their late 20s.

"The research found that following adolescence, the familial connection is an important factor in forming one's identity and living an independent life. It seems that not only can independence and closeness exist together, but they actually flourish together," Dr. Yanir said. (ANI)

Astronomers discover odd dwarf star with a magnetic personality

Thu, 06 Dec 2007 02:36:00 -0500

Astronomers have discovered a dwarf star that has an unusually active and complex magnetic field, stronger than our own Sun's, and a huge hot spot that covers half of its surface.

The team of astronomers, led by Dr. Edo Berger, a Carnegie-Princeton postdoctoral fellow at Princeton University, looked at the star TVLM513-46546 in the constellation Bootes about 35 light-years away by simultaneously using four different telescopes.

The observations by the different telescopes would help to explain the flamboyant activity of this M-type dwarf star, which are assumed to be cold, quiet and dim.

Like other ultracool dwarf stars, TVLM513-46546 is an M-type star with surface temperatures below about 2400K (2127 Celsius) and a mass of only 8 to 10 percent that of our Sun. By contrast, the Sun is a G-type star with an average surface temperature of 6000K (5727 Celsius).

The star's steady radio emission is interrupted with spectacular fireworks displays of minute-long flares. These flares come from the catastrophic collisions and merging of the magnetic fields in the corona of the star; these actions drive the annihilation of magnetic energy like a giant short-circuits in the fields. The team also observed soft x-ray emission and an x-ray flare.

According to reports from the Gemini Observatory, in Hilo, Hawaii, the ultracool M-type star has magnetic properties because it is convective. That is, the zone that transports heat to the surface of the star extends all the way from the stellar surface into the center, like the bubble of a huge boiling pot.

Such a simple structure has been predicted to generate a very basic magnetic field structure, perhaps more like the Earth's than the complex fields we see on the Sun.

But objects like TVLM513-46546 were once thought to have little or no magnetic field activity.

"Theory has always said that as we look at cooler and cooler stars, the coolest will be essentially dead," said Berger. "It turns out that stars like TVLM513-46546 have very complex magnetic activity around them, activity more like our Sun than that of a star that is barely functional," he added.

The research group also charted an optical hydrogen-alpha emission that is periodic and comes from a large hot spot. The two-hour emission period matches the two-hour rotation period of the star. "The periodic signal comes from a hot spot that covers half of the surface of the star like a giant light bulb that rotates in and out of our field of view," said Berger.

This star's complicated magnetic field environment and possible hot spot may indicate some unusual activity beneath the star's surface (in its dynamo) or possibly even the existence of a still-hidden companion.

"Though the idea of an unseen companion as an explanation for the star's excitable magnetic disposition is an intriguing one, but no such object has yet been detected," said Berger. "The main idea to consider here is an analogy to other systems where the presence of a companion directly or indirectly excites magnetic activity," he added.

In order to find out if this star is just a stellar oddity, or if it might turn out be a typical prototype of ultracool dwarfs, the research team plans to continue with observations of other such stars. The team expects the larger sample to show how other candidate low-mass stars and brown dwarfs (objects too hot to be planets and too cool to be stars) generate magnetic fields. (ANI)

Seeing adults doing something wrong makes it harder for kids to do it right

Thu, 06 Dec 2007 02:36:00 -0500

Children learn by imitating adults, in fact this occurs to such an extent that they will change their perception of how an object works if they see you using it in the wrong manner.

The finding is based on a study led by Derek Lyons, doctoral candidate, developmental psychology at Yale University, who found that children follow adults’ steps so faithfully that they actually change their mind about how an object functions.

“Even when you add time pressure, or warn the children not to do the unnecessary actions, they seem unable to avoid reproducing the adult’s irrelevant actions,” said Lyons.

“They have already incorporated the actions into their idea of how the object works,” he added.

Learning by imitation occurs from the simplest preverbal communication to the most complex adult expertise.

In the study three-to-five-year-old children who engaged in a series of exercises were reviewed.

In one exercise, the children could see a dinosaur toy through a clear plastic box.

The researcher used a sequence of irrelevant and relevant actions to retrieve the toy, such as tapping the lid of the jar with a feather before unscrewing the lid.

Then the little ones were asked which actions were silly and which were not.

The kids were praised when they pinpointed the actions that had no value in retrieving the toy. The idea behind such an experiment was to teach the children that the adult was unreliable and that they should ignore his unnecessary actions.

Later the children watched adults retrieve a toy turtle from a box using needless steps. When asked to do the task themselves, the children over-imitated, despite their prior training to ignore irrelevant actions by the adults.

“What of all of this means is that children’s ability to imitate can actually lead to confusion when they see an adult doing something in a disorganized or inefficient way. Watching an adult doing something wrong can make it much harder for kids to do it right,” Lyons said.

The study is published in Proceedings of the National Academy of Sciences. (ANI)