More space sugar.

How sweet it is! Four years ago, astronomers reported that they had for the first time detected sugar in space (SN: (6/24/00, p. 405). The same team has now found a second source of the simple sugar glycoaldehyde, in a dust-and-gas cloud 26,000 light-years from Earth. Glycoaldehyde can combine with other sugars to form ribose, the backbone of DNA and RNA.

In 2000, the researchers detected the molecule in a region of the star-forming cloud Sagittarius B2 that has a temperature of about 50 kelvins. In the Sept. 20 Astrophysical Journal Letters, the astronomers report finding glycoaldehyde in a region of the cloud with a temperature of just 8 kelvins.

Glycoaldehyde couldn't have formed at this low temperature, says study coauthor Philip Jewell of the National Radio Astronomy Observatory in Greenbank, W. Va. It must have gotten its start within dust grains in warmer regions of the cloud and then migrated to cooler regions, he notes.

Jewell's team suggests that shock waves in the cloud shattered the dust grains. The shock waves may have been generated by bubbles of gas driven from the star-forming parts of the cloud or by the infall of material into those star-forming sites, he adds.

Other star-forming clouds might also contain glycoaldehyde in chilly regions, says Jewell. These include the outer reaches of planet-spawning disks that swaddle young stars. The compound and others like it could be deposited on young planets, "possibly providing the molecular building blocks necessary for the creation of life," he notes.--R.C.