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Paper: Detection and Characterization of Nearby Giant Planet and Brown Dwarf Companions with an NGST Coronagraph
Volume: 212, From Giant Planets to Cool Stars
Page: 339
Authors: Sahai, Raghvendra; Trauger, J.; Stapelfeldt, K.; Moody, D.; Lunine, J.
Abstract: We describe a study of giant planet and brown dwarf companions to single stars within 20 parsecs of the Sun, as part of the NGST Design Reference Mission. These substellar objects can be directly detected from their high emission in the λ= 4.6-5.1 μm molecular opacity window through the use of a coronagraph and the nominal NGST wavefront. Combining the emergent fluxes from recent giant planet/brown dwarf atmosphere models, stellar data from the Gliese catalog, and a detailed model of coronagraph performance for the case of a seven segment primary mirror, we find that NGST will be capable of imaging planetary companions of Jupiter's mass, age, and orbital semi-major axis around all single stars within 8 pc of the Sun in integration times of three hours or less. Our proposed program of coronagraphic observations will carry out (1) a survey of the nearest 180 single stars for Jupiter-like companions complete to 8 pc, (2) a survey of the nearest 500 single stars for more luminous (i.e. younger or more massive) companions complete to a 5 μm flux level 40 times that of Jupiter, and (3) detailed spectrophotometric study of selected objects discovered in these two surveys. These observations can be expected to provide results of fundamental importance to our understanding of planetary systems and their frequency in the galaxy: (1) the first determination of the giant planet/brown dwarf luminosity function, (2) the first spectral characterization of these objects across a broad range of effective temperatures, and (3) the first direct images of planets orbiting another star.
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