May 18 2006
From The Space Library
A team of European astronomers, led by Christophe Lovis of the Observatoire de Genève in Switzerland, reported in Nature their discovery of a new system of three extrasolar planets in the constellation Puppis. The discovery of the three planets orbiting the Sun-like star HD 69830, which is approximately 41 light-years from Earth, marked the first time that astronomers had identified a system composed of several planets, each planet possessing a mass approximating that of Neptune. Theoretical calculations of the complexion of the three planets had indicated that the two closest to HD 69830 have a rocky composition similar to the planet Mercury. The astronomers reported that the outermost planet likely has a significant gaseous envelope, surrounding a core composed of rock or ice or a combination of the two, and that the temperatures of the planet are moderate enough to allow the existence of liquid water. The team had discovered the planets using the European Southern Observatory’s 3.6-meter (11.8-foot) telescope at the La Silla Observatory in Chile. The telescope was equipped with a precise spectrograph to detect small wobbles induced by the Puppis planets in the HD 69830 star. The technique of detecting and studying these wobbles enabled astronomers to measure the gravitational influence of a planet on its parent star and, thereby, to infer the planet’s presence.
Christophe Lovis et al., “An Extrasolar Planetary System with Three Neptune-Mass Planets,” Nature 441, no. 7091 (18 May 2006): 305–309; Dennis Overbye, “Planet Group Similar to Solar System Is Found,” New York Times, 18 May 2006; Ker Than, “Planets Found in Potentially Habitable Setup,” Space.com, 17 May 2006, http://www.space.com/scienceastronomy/060517_neptune_planets.html (accessed 24 June 2010).
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