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5 December 2013 11:26 am ,
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An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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And the Meek Shall Inherit Some Earths
20 October 2005 (All day)
Though it's not quite a star, the humble brown dwarf may still have hidden talents. New evidence suggests that dust clouds orbiting the celestial objects could be breeding grounds for planets, just like those around true stars.
Planet-building begins when the dust grains swirling around young stars stick together and grow crystals. The dust also tends to flatten into a thin disk over time. Crystallization requires high temperatures, which are thought to be supplied by the star's radiation. As a result, astronomers had assumed that brown dwarfs, which weigh roughly between 1 and 9 percent of the Sun and have cores that do not get hot enough to burn hydrogen as normal stars do, are too cool to transform their local dust into planets.
To test this, astronomer Dániel Apai of the University of Arizona and his colleagues used the Spitzer Space Telescope to study a subset of brown dwarfs in a nearby star-forming region, which is 1 million to 3 million years old. In 6 of their 8 targets, the team found infrared emissions indicative of silicate dust grains. They then observed that this dust was growing, crystallizing and settling towards a flatter disk. The results could mean that brown dwarfs can form planets, the researchers report 21 October in Science. "We think if they start, they will finish," Apai says.
Still, there are many uncertainties in how planets form and not all dust grains will become planets, says astronomer Leonardo Testi of the Osservatorio Astrofisico di Arcetri in Florence, Italy. Theory predicts that these pebble-sized objects will tend to destroy each other when they collide, rather than clump together, he says. Moreover, scientists have a hard time tracking such grains because, as they grow larger, they emit longer wavelengths that are increasingly difficult to detect. The possibility that brown dwarfs may harbor planets is intriguing, however, says Testi, especially since these objects constitute some of our nearest neighbors.