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Multiplicity of Nearby Free-floating Ultracool Dwarfs: A Hubble Space Telescope WFPC2 Search for Companions
We present Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations of a sample of 134 ultracool objects (spectral types later than M7) coming from the Deep Near InfraredExpand
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Discovery of Young, Isolated Planetary Mass Objects in the σ Orionis Star Cluster
We present the discovery by optical and near-infrared imaging of an extremely red, low-luminosity population of isolated objects in the young, nearby stellar cluster around the multiple, massive starExpand
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The Substellar Mass Function in σ Orionis
We combine results from imaging searches for substellar objects in the σ Orionis cluster and follow-up photometric and spectroscopic observations to derive a census of the brown dwarf population in aExpand
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An Effective Temperature Scale for Late-M and L Dwarfs, from Resonance Absorption Lines of Cs I and Rb I
We present Keck HIRES spectra of six late-M dwarfs and 11 L dwarfs. Our goal is to assign effective temperatures to the objects using detailed atmospheric models and fine analysis of the alkaliExpand
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PERIODIC RADIO AND Hα EMISSION FROM THE L DWARF BINARY 2MASSW J0746425+200032: EXPLORING THE MAGNETIC FIELD TOPOLOGY AND RADIUS OF AN L DWARF
We present an 8.5 hr simultaneous radio, X-ray, UV, and optical observation of the L dwarf binary 2MASSW J0746425+200032. We detect strong radio emission, dominated by short-duration periodic pulsesExpand
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Space Velocities of L- and T-type Dwarfs
We have obtained radial velocities of a sample of 18 ultracool dwarfs (M6.5-T8) using high-resolution, near-infrared spectra obtained with NIRSPEC and the Keck II telescope. We have confirmed thatExpand
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Dynamical Masses of the Binary Brown Dwarf GJ 569 Bab
We have obtained new images and high-resolution (R ~ 22,400) near-infrared (1.2400-1.2575 μm) spectra of each component of the brown dwarf binary GJ 569 Bab using the adaptive optics facility of theExpand
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The substellar mass function in σ Orionis II. Optical, near-infrared and IRAC/Spitzer photometry of young cluster brown dwarfs and planetary-mass objects ,
Aims. We investigate the mass function in the substellar domain down to a few Jupiter masses in the young σ Orionis open cluster (3 ± 2M a,d = 360 +70 −60 pc). Methods. We have performed a deepExpand
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A Methane isolated planetary mass object in orion
We report on the discovery of a free-floating methane dwarf toward the direction of the young star cluster σ Ori. Based on the object's far-red, optical, and near-infrared photometry andExpand
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Spectroscopy of a Brown Dwarf Candidate in the alpha Persei Open Cluster
We report intermediate-resolution spectroscopy in the range 625-775 nm of a faint (R∼19) very late type object, discovered in two CCD images taken near the center of the α Per cluster. The spectrumExpand
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