| Vast amounts of water and chemicals essential for life have been found circling a young star in the region where planets form. Water has been found in the same zone around two other infant stars.
Their results also suggest that these molecules were created around the young suns and did not condense from the dense clouds of gas between the stars. The news follows the separate discovery of organic molecules around another star by the Hubble space telescope, reported in January. Scientists hope the new results from AA Tauri, 450 light-years from Earth, will shed new light on how our own solar system formed and how life can develop on other worlds. The breakthrough was made by John Carr, of the Naval Research Laboratory, Washington, and Joan Najita, of the National Optical Astronomy Observatory, at Tucson, Arizona. They developed a new technique to increase the capabilities of Spitzer’s infrared spectrograph so they they could learn more about how the gases are distributed in the planet-forming disks. These flattened disks of gas and dust that encircle young stars are believed to provide the building materials for planets and moons and eventually, over millions of years, evolve into orbiting planetary systems like our own. Car said: “Most of the material within the disks is gas, but until now it has been difficult to study the gas composition in the regions where planets should form. Much more attention has been given to the solid dust particles, which are easier to observe.” Carr and Najita took a close look at the gases in the planet-forming region around AA Tauri. They were able to detect the minute spectral signatures for three simple organic molecules – hydrogen cyanide, acetylene and carbon dioxide – plus water vapour. They also found there are more of these substances in the dense interstellar gas, called molecular clouds, from which the disk originated. Car said: “Molecular clouds provide the raw material from which the protoplanetary disks are created. So this is evidence for an active organic chemistry going on within the disk, forming and enhancing these molecules.” A separate team from the California Institute of Technology used the same technique with Spitzer to find water molecules in the disks around two other young stars. The chief investigator on that team, Colette Salyk, said: “This is one of the very few times that water vapour has been directly shown to exist in the inner part of a protoplanetary disk – the most likely place for terrestrial planets to form.” Previous exciting results from Spitzer include evidence that a planet like Earth is forming around a star in Centaurus. Picture: An artist’s impression of a very young star encircled by a disk of gas and dust, the raw materials from which rocky planets such as Earth are thought to form. (Nasa/JPL-Caltech). |
