Two newly found space molecules.

Adding to the growing body of evidence that space is rich in organic molecules, researchers have detected two new organic chemicals in a large interstellar cloud. Known as Sagittarius B2, this extremely cold mass of star-forming gas and dust is located near the center of the Milky Way galaxy.

To identify the carbon-containing molecules, Jan M. Hollis of the NASA Goddard Space Flight Center in Greenbelt, Md., and his colleagues looked for the emission of specific frequencies of radio waves from the cloud. Different types of molecules emit energy at different frequencies, each producing a unique signal that researchers can detect with powerful telescopes. In the July 20 Astrophysical Journal Letters, the researchers report recording the frequencies associated with two aldehydes called propenal and propanal, which consist of 8 and 10 atoms, respectively, and include three carbons each.

Although astrochemists have found organic molecules in space before (SN: 5/1/04, p. 280), Hollis says that the evidence of the two aldehydes will help researchers understand how molecular building blocks assemble into more-complex organic molecules in space. For instance, adding two hydrogen atoms to a molecule of propenal yields propanal, and both molecules serve as intermediates in the formation of larger and more-complex compounds.--A.G.