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Green Bank Telescope Finds New Molecules in Milky Way

Posted on: Wednesday, 23 June 2004, 06:00 CDT

Two new molecules have been discovered in an interstellar cloud of gas and dust near the center of the Milky Way Galaxy by a team of scientists using the new Robert C. Byrd Green Bank Telescope.

The discovery, announced by the National Radio Astronomy Observatory's headquarters in Charlottesville, Va., marks the Green Bank Telescope's first detection of new molecules. The discovery is already helping astronomers better understand the complex processes by which large molecules form in space, according to the NRAO.

The eight-atom molecule propenal and the 10-atom molecule propanal were detected 26,000 light years away in an area known as Sagittarius B2. Interstellar clouds such as the one in which the molecules were detected are often many light-years across, and contain the raw material from which new stars are formed.

"Though very rarefied by Earth standards, these interstellar clouds are the sites of complex chemical reactions that occur over hundreds of thousands or millions of years," said Jan M. Hollis of NASA's Goddard Space Flight Center in Greenbelt, Md., and a member of the team that discovered the molecules.

"Over time, more and more complex molecules can be formed in these clouds," Hollis said. "At present, however, there is no accepted theory addressing how interstellar molecules containing more than five atoms are formed."

So far, about 130 different molecules, most of them containing a small number of atoms, have been discovered in interstellar clouds. The molecules found through the search using the Green Bank Telescope were among a relative few newly discovered molecules consisting of 8 or more atoms.

Each new discovery of a molecule helps to define the formation chemistry and nature of interstellar dust grains, believed to be the formation sites for most complex interstellar molecules.

Collaborating with Hollis in the discovery were Anthony Remijan, also of NASA Goddard; Frank J. Lovas of the National Institute of Standards and Technology in Gaithersburg, Md.; Harald Mollendal of the University of Oslo in Norway, and Philip Jewell, site director at the National Radio Astronomy Observatory at Green Bank. Their results have been accepted for publication in the Astrophysical Journal of Letters.

Molecules consisting of carbon, hydrogen and oxygen atoms, such as those discovered through the Green Bank observations, are of particular interest to scientists, since they could contain the building blocks for life to begin on a new planet.

Complex molecules in space such as those detected with the Green Bank Telescope could have been transported to our solar system by comets, and played a role in the formation of biologically significant molecules on the early Earth.

"The Green Bank Telescope can be used to fully explore the possibility that a significant amount of pre-biotic chemistry may occur in space long before it occurs on a newly formed planet," said Remijan. "Comets form from interstellar clouds and incessantly bombard a newly formed planet early in its history. Craters on our Moon attest to this. Thus, comets may be the delivery vehicles for organic molecules necessary for life to begin on a new planet."

The large diameter and high precision of the Green Bank Telescope, the world's largest fully steerable radio telescope, "allowed us to study small interstellar clouds that can absorb the radiation from a bright background source," said Jewell.

"The sensitivity and flexibility of the telescope gave us an important new tool for the study of complex interstellar molecules."

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