Properties of the Coolest Dwarfs

S.K. Leggett, R. Freedman, T. Geballe, D. Golimowski, N. Lodieu, M. Marley, D.J. Pinfield, D. Saumon, D. Stephens, S.J. Warren

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Abstract

Eleven years after the discovery of the first T dwarf, a population of ultracool L and T dwarfs has been identified that is large enough to show a range of atmospheric properties. Also, model atmospheres are sufficiently advanced to study these properties in detail. Since the last Cool Stars meeting, several observational developments have aided in these studies. We present recent mid-infrared photometry and spectroscopy from the Spitzer Space Telescope which confirms the prevalence of vertical mixing in the atmospheres of L and T dwarfs. Hence, the 700 K to 2200 K L and T dwarf photospheres require several parameters for successful modelling: effective temperature, gravity, metallicity, grain sedimentation efficiency and vertical mixing efficiency. We also describe initial results of a search for ultracool dwarfs in the UKIRT Infrared Deep Sky Survey, and present the latest T dwarf found to date. We conclude with a discussion of the possible spectral indicators of Y dwarfs.
Original languageEnglish
Title of host publicationIn: Procs of the 14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun - ASP Conf Series 384
PublisherAstronomical Society of the Pacific
Pages98-110
ISBN (Print)978-1-58381-332-4, 978-1-58381-331-7
Publication statusPublished - 2008

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