منابع مشابه
Infrared Parallaxes for Methane T Dwarfs
We report final results from our 2.5 year infrared parallax program carried out with the European Southern Observatory 3.5m New Technology Telescope and the SOFI infrared camera. Our program targeted precision astrometric observations of ten T type brown dwarfs in the J band. Full astrometric solutions (including trigonometric parallaxes) for nine T dwarfs are provided along with proper motion ...
متن کاملParallaxes of L and T dwarfs
We discuss a new program to measure the parallaxes of a number of L and T dwarfs, objects that bridge the gap between M dwarfs and planets. This pilot project tests the feasibility of using large telescopes with infrared detectors to determine parallaxes at the level of milli-arcseconds (mas). First results show that we are able to achieve the required centroiding precision and simulations indi...
متن کاملMethane and the Spectra of T Dwarfs
We have updated our PHOENIX model atmospheres and theoretical spectra for ultracool dwarfs with new opacity data for methane based on line strength predictions with the STDS software. By extending the line list to rotational levels of J = 40 we can significantly improve the shape of the near-IR absorption features of CH4, and in addition find an enhanced blanketing effect, resulting in up to 50...
متن کاملThe Near-infrared and Optical Spectra of Methane Dwarfs and Brown Dwarfs
We identify the pressure–broadened red wings of the saturated potassium resonance lines at 7700 Å as the source of anomalous absorption seen in the near-infrared spectra of Gliese 229B and, by extension, of methane dwarfs in general. In broad outline, this conclusion is supported by the recent work of Tsuji et al. 1999. The WFPC2 I band measurement of Gliese 229B is also consistent with this hy...
متن کاملA Unified Near-infrared Spectral Classification Scheme for T Dwarfs
A revised near-infrared classification scheme for T dwarfs is presented, based on and superseding prior schemes developed by Burgasser and coworkers and Geballe and coworkers, and defined following the precepts of the MK process. Drawing from two large spectroscopic libraries of T dwarfs identified largely in the SloanDigital Sky Survey and the Two Micron All Sky Survey, nine primary spectral s...
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ژورنال
عنوان ژورنال: The Astronomical Journal
سال: 2003
ISSN: 0004-6256,1538-3881
DOI: 10.1086/376481