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Universe's first stars not so big after all
IN BRIEF
nasa/jpl
JUPITER’S icy moon Europa is pockmarked by curious domes and depressions. How they formed has been a mystery, but now it seems they are areas where liquid water once appeared close to the surface. Europa is thought to harbour a saltwater ocean, sandwiched between a 20-kilometre-thick layer of surface ice and a rocky core below. For clues as to what might be happening there, Britney Schmidt of the University of Texas, Austin, and colleagues looked at studies of subglacial volcanoes and ice shelves on Earth. They concluded that ice rising from the bottom of Europa’s surface layer created its 300-metrehigh “chaos terrains” (Nature, DOI: 10.1038/nature10608). As Europa orbits Jupiter, it flexes as a result of slight variations in the gravitational tug of the giant planet. The energy that goes into this bending is converted into heat that warms the bottom of the surface ice, pushing plumes of it upwards. This changes the pressure in the ice above, creating pockets of liquid water. The water breaks up the overlying ice and refreezes over tens of thousands of years, creating jumbled domes. A large dark spot on Europa called Thera Macula (shown below) could result from warm ice rising beneath it, says Schmidt. “We are probably witnessing active chaos formation.”
22 | NewScientist | 19 November 2011
Universe’s first stars were more like suns than supergiants THE earliest stars may have been less than half as large as previously thought. The new size limit could resolve one of astronomy’s oldest mysteries: why some elements are more abundant than theory predicts. In the first hundreds of millions of years after the big bang, the earliest stars formed from atomic hydrogen, helium and tiny amounts of other light elements. Initial calculations showed that these stars would have grown to between 100 and 200 times the mass of our sun.
Now a team led by Takashi Hosokawa at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, has used computer simulations to show the gas clouds from which the stars formed would have been much hotter than thought. “That hot gas expands and doesn’t accrete onto the disc [that eventually forms the star],” says Harold Yorke, a member of the JPL team. Consequently, the early stars must have had masses closer to 40 times that of our sun (Science, DOI: 10.1126/science.1207433).
Stars around this size help to explain the distribution of elements we see today. When the first stars exploded as supernovas, they spewed out new elements in proportions that depended on the mass of the explosion. However, the explosive deaths of stars of around 100 solar masses or more could not have produced the elements in the proportions that astronomers see. By contrast, the ratios are exactly what you would expect from the smaller supernovas predicted by Hosokawa’s team. Andreas Szego/plainpicture
Ice plumes made Europa’s domes
For new stories every day, visit newscientist.com/news
Supermice run far and dodge diabetes FASTER, further… fatter? Knocking out a particular gene in muscle lets mice run twice as far as normal; knocking out the same gene in fat cells allows the animals to put on weight without developing type-2 diabetes. The discoveries could lead to new treatments for diabetes or for people with wasting diseases, say Johan Auwerx of the Federal Polytechnic School of Lausanne, Switzerland, and colleagues. The team knocked out the gene for a protein called nuclear receptor corepressor 1 (NCoR1) in the muscles of mice. Without NCoR1, mitochondria – which power cells – keep working at full speed. “The treated mice ran 1600 metres in 2 hours, compared with 800 metres for untreated mice,” Auwerx says (Cell, DOI: 10.1016/j.cell.2011.10.017). Athletes shouldn’t be tempted to try this, though, as knocking out the gene could have unpredictable side effects. Another experiment reported in Cell gives an example: Auwerx found that knocking out NCoR1 in fat cells alone made the mice get fatter, but they didn’t develop type-2 diabetes (DOI: 10.1016/ j.cell.2011.09.050).
Why dyed hair is dull and lifeless DRY, damaged, oily, blond? When it comes to hair type only thickness and dye really matter. That’s according to researchers at Procter & Gamble, who have used atomic force microscopy – which generates nanoscale images – and micro-CT scanning to analyse the interactions between chemicals and hair fibres. They found the most significant differences are between thick, fine and coloured hair. Hair is usually coated with a protective layer of oil that is uncharged and repels water. Bleach and dye strip away this layer, causing
hair to become negatively charged and attract water. This means that uncharged chemicals such as silicon – added to shampoo to make hair soft and shiny – will no longer stick. This has led to the development of amino silicones, whose charge means they do stick to coloured hair (International Journal of Cosmetic Science, DOI: 10.1111/j.1468-2494.2010.00540.x). The scans also showed that fine hair funnels water, so ingredients in shampoo need to be extra sticky to have any effect. Thick hair creates a kind of sieve so ingredients need to be bigger to work their magic.
nasa/jpl
JUPITER’S icy moon Europa is pockmarked by curious domes and depressions. How they formed has been a mystery, but now it seems they are areas where liquid water once appeared close to the surface. Europa is thought to harbour a saltwater ocean, sandwiched between a 20-kilometre-thick layer of surface ice and a rocky core below. For clues as to what might be happening there, Britney Schmidt of the University of Texas, Austin, and colleagues looked at studies of subglacial volcanoes and ice shelves on Earth. They concluded that ice rising from the bottom of Europa’s surface layer created its 300-metrehigh “chaos terrains” (Nature, DOI: 10.1038/nature10608). As Europa orbits Jupiter, it flexes as a result of slight variations in the gravitational tug of the giant planet. The energy that goes into this bending is converted into heat that warms the bottom of the surface ice, pushing plumes of it upwards. This changes the pressure in the ice above, creating pockets of liquid water. The water breaks up the overlying ice and refreezes over tens of thousands of years, creating jumbled domes. A large dark spot on Europa called Thera Macula (shown below) could result from warm ice rising beneath it, says Schmidt. “We are probably witnessing active chaos formation.”
22 | NewScientist | 19 November 2011
Universe’s first stars were more like suns than supergiants THE earliest stars may have been less than half as large as previously thought. The new size limit could resolve one of astronomy’s oldest mysteries: why some elements are more abundant than theory predicts. In the first hundreds of millions of years after the big bang, the earliest stars formed from atomic hydrogen, helium and tiny amounts of other light elements. Initial calculations showed that these stars would have grown to between 100 and 200 times the mass of our sun.
Now a team led by Takashi Hosokawa at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, has used computer simulations to show the gas clouds from which the stars formed would have been much hotter than thought. “That hot gas expands and doesn’t accrete onto the disc [that eventually forms the star],” says Harold Yorke, a member of the JPL team. Consequently, the early stars must have had masses closer to 40 times that of our sun (Science, DOI: 10.1126/science.1207433).
Stars around this size help to explain the distribution of elements we see today. When the first stars exploded as supernovas, they spewed out new elements in proportions that depended on the mass of the explosion. However, the explosive deaths of stars of around 100 solar masses or more could not have produced the elements in the proportions that astronomers see. By contrast, the ratios are exactly what you would expect from the smaller supernovas predicted by Hosokawa’s team. Andreas Szego/plainpicture
Ice plumes made Europa’s domes
For new stories every day, visit newscientist.com/news
Supermice run far and dodge diabetes FASTER, further… fatter? Knocking out a particular gene in muscle lets mice run twice as far as normal; knocking out the same gene in fat cells allows the animals to put on weight without developing type-2 diabetes. The discoveries could lead to new treatments for diabetes or for people with wasting diseases, say Johan Auwerx of the Federal Polytechnic School of Lausanne, Switzerland, and colleagues. The team knocked out the gene for a protein called nuclear receptor corepressor 1 (NCoR1) in the muscles of mice. Without NCoR1, mitochondria – which power cells – keep working at full speed. “The treated mice ran 1600 metres in 2 hours, compared with 800 metres for untreated mice,” Auwerx says (Cell, DOI: 10.1016/j.cell.2011.10.017). Athletes shouldn’t be tempted to try this, though, as knocking out the gene could have unpredictable side effects. Another experiment reported in Cell gives an example: Auwerx found that knocking out NCoR1 in fat cells alone made the mice get fatter, but they didn’t develop type-2 diabetes (DOI: 10.1016/ j.cell.2011.09.050).
Why dyed hair is dull and lifeless DRY, damaged, oily, blond? When it comes to hair type only thickness and dye really matter. That’s according to researchers at Procter & Gamble, who have used atomic force microscopy – which generates nanoscale images – and micro-CT scanning to analyse the interactions between chemicals and hair fibres. They found the most significant differences are between thick, fine and coloured hair. Hair is usually coated with a protective layer of oil that is uncharged and repels water. Bleach and dye strip away this layer, causing
hair to become negatively charged and attract water. This means that uncharged chemicals such as silicon – added to shampoo to make hair soft and shiny – will no longer stick. This has led to the development of amino silicones, whose charge means they do stick to coloured hair (International Journal of Cosmetic Science, DOI: 10.1111/j.1468-2494.2010.00540.x). The scans also showed that fine hair funnels water, so ingredients in shampoo need to be extra sticky to have any effect. Thick hair creates a kind of sieve so ingredients need to be bigger to work their magic.