10,821 research outputs found

    【Concluding Remarks 3】

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    Theoretical Transmission Spectra During Extrasolar Giant Planet Transits

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    The recent transit observation of HD 209458 b - an extrasolar planet orbiting a sun-like star - confirmed that it is a gas giant and determined that its orbital inclination is 85 degrees. This inclination makes possible investigations of the planet atmosphere. In this paper we discuss the planet transmission spectra during a transit. The basic tenet of the method is that the planet atmosphere absorption features will be superimposed on the stellar flux as the stellar flux passes through the planet atmosphere above the limb. The ratio of the planet's transparent atmosphere area to the star area is small, approximately 10^{-3} to 10^{-4}; for this method to work very strong planet spectral features are necessary. We use our models of close-in extrasolar giant planets to estimate promising absorption signatures: the alkali metal lines, in particular the Na I and K I resonance doublets, and the He I 23S2^3S - 23P2^3P triplet line at 1083.0 nm. If successful, observations will constrain the line-of-sight temperature, pressure, and density. The most important point is that observations will constrain the cloud depth, which in turn will distinguish between different atmosphere models. We also discuss the potential of this method for EGPs at different orbital distances and orbiting non-solar-type stars.Comment: revised to agree with accepted paper, ApJ, in press. 12 page

    Oil supply forecasting : a disaggregated process approach

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    This paper represents a collective effort by the Supply Analysis Group of the M.I.T. World Oil Project which is supported by the U.S. National Science Foundation under Grant no. SIA75-00739.U.S. National Science Foundation under Grant no. SIA75-00739

    Colonization Success by Green Iguanas in Florida

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    Colonization Success by Green Iguanas in Florida

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    Implications of Biomechanical Characters of Subterranean Clover on Feeding by Redlegged Earth Mite and Intake by Sheep

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    The biomechanical strength of cultivars of subterranean clover (Trifolium subterraneum) that were either resistant or susceptible to feeding by redlegged earth mite was measured as the force required to penetrate their leaves with a small, tubular punch. Cotyledons and trifoliate leaves of cultivars resistant to redlegged earth mite had a higher resistance to penetration than cultivars susceptible to redlegged earth mite. Cotyledons needed a higher force to penetrate than trifoliate leaves. The possible implications for intake by ruminants of differences between the cultivars in biomechanical characters are also considered
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