April 7, 2009

Spitzer looks for prebiotic chemicals

U.S.-led astronomers say new data hint that planets around stars cooler than the sun might have a differing mix of life-forming prebiotic chemicals.

The astronomers used the Spitzer space telescope to look for a prebiotic chemical called hydrogen cyanide in the planet-forming material swirling around different types of stars. Hydrogen cyanide is a component of adenine that is a basic element of DNA, which is found in every living organism on Earth.

The researchers said they detected hydrogen cyanide molecules in disks circling yellow stars like the sun but found none around cooler and smaller stars, such as the reddish-colored M-dwarfs and brown dwarfs common throughout the universe.

Prebiotic chemistry may unfold differently on planets around cool stars, said Ilaria Pascucci of Johns Hopkins University, lead author of the study. It is plausible that life on Earth was kick-started by a rich supply of molecules delivered from space.

The study that included scientists from the Space Telescope Science Institute in Baltimore, Pennsylvania State University, Germany's Max Planck Institute for Astronomy, the University of Arizona, the Netherlands Institute for Space Research and Italy's Arcetri Astrophysical Observatory is to appear in the April 10 issue of the Astrophysical Journal.