Astronomers have discovered a new way to probe dark clouds of gas and dust in space, shedding light on the mysterious conditions that nurture star birth.
Stars condense from giant clouds of molecular gas and dust that float through space. But these stellar wombs are difficult to study because they are barely visible at optical wavelengths. And other methods that probe their structure are not very precise 鈥� for example, estimating how much dust they contain by how red the stars behind them appear.
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Now, two researchers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, US, have imaged the clouds鈥� structure at a resolution 50 times better than previous techniques.
They stumbled on the discovery by taking a four-hour infrared exposure of molecular clouds with a 3.5-metre telescope in Spain. 鈥淭he image just looks dark and empty in the optical, but in the near-infrared, there鈥檚 all this colour and structure,鈥� says Jonathan Foster, one of the pair.
Foster and colleague Alyssa Goodman have dubbed the infrared emission 鈥渃loudshine鈥� and believe it comes from faint, infrared light that the clouds scatter from surrounding stars.
Shape and density
The cloudshine traces the shape and density of the clouds because its colour depends on how much dust it has bounced off. Shorter wavelengths scatter off dust at the edges of the clouds, while longer wavelengths make it to the clouds鈥� central regions before bouncing off dust particles there.
The images may help researchers understand exactly what triggers star birth. 鈥淲e鈥檙e interested in knowing what physical processes are important in determining the shape of molecular clouds and how that proceeds to star formation,鈥� Foster told New 杏吧原创.
鈥淭he only way we can do this is by finding a way to look at the density structure of real clouds and comparing them to simulations鈥� that take into account phenomena such as magnetic fields, he says.
The research was part of the Coordinated Molecular Probe Line Extinction Thermal Emission (COMPLETE) survey, which involves studying three star-forming regions relatively close to Earth at a variety of wavelengths. 鈥淲e鈥檙e very interested in seeing where different methods work well and where different methods fail,鈥� Foster says.
The results have been submitted for publication in the Astrophysical Journal Letters.
