Astronomers have long wondered how giant gas planets like Jupiter and Saturn form. Now scientists say that they may have caught this development in action. According to a report in the current issue of the journal Nature, recent detection of the hydrogenic ion (a hydrogen molecule with an additional proton) around a distant star may signal the presence of a gas-giant protoplanet.

Sean D. Brittain and Terrence W. Rettig of the University of Notre Dame used the NASA Infrared Telescope to study the star HD141569, which is located 320 light years from Earth. The telescope identified the spectral signature of the hydrogenic ion, which has been detected in our own solar system in the upper atmospheres of Jupiter, Saturn and Uranus. What is more, the researchers also discovered carbon monoxide emanating from the star's surroundings, which is surprising because carbon monoxide effectively destroys hydrogenic ions. Brittain and Rettig posit that the carbon monoxide is present in an outer ring circling the star at a distance roughly 10 times the distance separating the Earth from the sun. The gas in the interior of this disk, the team suggests, may have already condensed into a clump that marks the beginnings of planet formation; if so, the hydrogenic ions could be originating from the outer atmosphere of this protoplanet.

More observations will be required to fully verify the new results. But according to Takeshi Oka of the University of Chicago, "if the findings are confirmed, Brittain and Rettig have discovered a new astronomical object, opening up a new avenue for the study of the formation of giant planets."