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Research by two University of Notre Dame astronomers may shed new light on how planets are formed. Terrence W. Rettig, professor of physics, and graduate student Sean Brittain report their findings in last Thursday's edition of the scientific journal Nature. Even though an Earth-like planet never has been detected outside the solar system, the formation process for these smaller planets is fairly well understood. Observations of infrared and radio emission from dust in space have revealed the presence of protoplanetary disks where dust grains likely accumulate to form rocky planets like Earth. It's a mystery, however, as to how gas giant planets, such as Jupiter and Saturn, form from the remaining primordial hydrogen and helium gas in the disk. The time scale as to how and when this occurs after the formation of Earth-like planets is unknown. Rettig and Brittain have been studying a protoplanetary disk around the star HD141569, located 320 light years from Earth. Particularly intriguing is the fact that they have found emission of gaseous H3+ ions coming from the region around the star. The only previous detection of H3+ emission of this type was in the upper atmospheres of Jupiter, Saturn, Uranus and Neptune. Rettig and Brittain cautiously point out that the detection of H3+ emission may indicate the existence of a forming gas giant planet, or shocked hydrogen gas at the inner edge of the disk. Higher resolution observations are needed to determine if the detection indicates the existence of a large gaseous protoplanet that may eventually form a Jupiter-like planet. However, the prospect is intriguing because this would be the first direct detection of light from an extrasolar planet or protoplanet. Even if future work shows the H3+ originates from the inner disk, the results will provide astronomers important information on how the material surrounding the star evolves chemically. Also, of the 20 stars observed by Rettig and Brittain, H3+ emission was only detected from the more evolved disk around HD141569. Related Links Dept of Physics University of Notre Dame SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express 
Searching For Worlds Beyond Sol
Paris - Jun 27, 2002The last five days have witnessed the unprecedented announcement of 25 new planet discoveries. These discoveries are split almost evenly between European and American astronomers. Didier Queloz and his colleagues at the Observatoire de Genève, Switzerland, have found a dozen of the new planets. Their discoveries include the most tantalising one yet: a planet that closely resembles Jupiter in our own Solar System. The find brings astronomers another step closer to detecting an Earth-like world. |
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