Astronomers know that the dusty and rocky interiors of comets contain heavy metals. But since solid metals typically do not sublimate – become gaseous from the solid state immediately – at low temperatures, researchers did not expect to find heavy metals in the atmospheres of cold comets venturing away from the sun. . Nickel and iron vapors have now even been detected in comets observed more than 480 million kilometers from the sun – more than three astronomical units, the average distance between Earth and the sun.
The STAR Institute team also discovered that the atmospheres of comets contain roughly equal amounts of iron and nickel. Typically, materials in our solar system, such as those from the sun and meteorites, contain about ten times more iron than nickel. This new finding therefore has implications for our understanding of the origin of comets and the early solar system, although the team is not yet sure of its implications.
“Comets formed about 4.6 billion years ago in the very young solar system, and have not changed since. In a way, they are astronomical fossils,” said the co- author Emmanuel Jehin.
Although the Belgian team has been studying these “ fossil ” objects for almost twenty years with the Very Large Telescope (VLT) of the European Southern Observatory (ESO), the researchers had so far not noticed the presence of nickel and iron in their atmospheres. “This discovery has escaped our attention for years,” Jehin said.
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