Chameleon I Spectral Graphic

Astronomers have taken an inventory of the most deeply embedded ices in a cold molecular cloud to date. They used light from a background star, named NIR38, to illuminate the dark cloud called Chameleon I. Ices within the cloud absorbed certain wavelengths of infrared light, leaving spectral fingerprints called absorption lines. These lines indicate which substances are present within the molecular cloud.

These graphs show spectral data from three of the James Webb Space Telescope’s instruments. In addition to simple ices like water, the science team was able to identify frozen forms of a wide range of molecules, from carbon dioxide, ammonia, and methane, to the simplest complex organic molecule, methanol.

In addition to the identified molecules, the team found evidence for prebiotic molecules more complex than methanol (indicated in the lower-right panel). Although they didn't definitively attribute these signals to specific molecules, this proves for the first time that complex molecules form in the icy depths of molecular clouds before stars are born.

The upper panels and lower-left panel all show the background star’s brightness versus wavelength. A lower brightness indicates absorption by ices and other materials in the molecular cloud. The lower-right panel displays the optical depth, which is essentially a logarithmic measure of how much light from the background star gets absorbed by the ices in the cloud. It is used to highlight weaker spectral features of less abundant varieties of ice.