Astronomers think they may know how some organic molecules form in space, thanks to the powerful light of young stars.
Using NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), a Dutch-French team of astronomers studied the composition of NGC 7023, a nebula 1,300 light-years from Earth that is lit by a bright young star. They discovered that larger, more complex molecules are found closer to the star, indicating that strong ultraviolet emissions could play a role in the formation of these chemicals.
The researchers studied polycyclic aromatic hydrocarbons (PAHs), which are formed on Earth in the smoke produced by burning organic materials like meat or sugarcane. They are made by carbon organized in a honeycomb structure, and 10 percent of all the carbon in the universe is found in these PAHs.
Current models suggest that young stars, like the one illuminating NGC 7023, destroy the largest molecules, but it appears that this is not the case here.
In the study, published in Astronomy and Astrophysics, the researchers analyzed the size of molecules across the nebula. They found a distinct lack of small- and intermediate-sized molecules near the star. The intense ultraviolet radiation should be destroying the molecules, but instead it is pushing the medium-sized chemicals together, forcing them to join into larger, more complex structures.
The observations were possible thanks to the unique capabilities of SOFIA, a one-of-a-kind infrared observatory. The telescope is installed inside a Boeing 747, and it operates at an altitude of 12 kilometers (7.5 miles), which is high enough to not be affected by the water vapor in the atmosphere.
“The success of these observations depended on both SOFIA’s ability to observe wavelengths inaccessible from the ground, and the large size of its telescope, which provided a more detailed map than would have been possible with smaller telescopes,” said co-author Olivier Berné at CNRS, the National Center for Scientific Research in Toulouse, France, in a statement.
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