657 research outputs found
Direct Detection of the Brown Dwarf GJ 802B with Adaptive Optics Masking Interferometry
We have used the Palomar 200" Adaptive Optics (AO) system to directly detect
the astrometric brown dwarf GJ 802B reported by Pravdo et al. 2005. This
observation is achieved with a novel combination of aperture masking
interferometry and AO. The dynamical masses are 0.1750.021 M and
0.0640.032 M for the primary and secondary respectively. The
inferred absolute H band magnitude of GJ 802B is M=12.8 resulting in a
model-dependent T of 1850 50K and mass range of
0.057--0.074 M.Comment: 4 Pages, 5 figures, emulateapj format, submitted to ApJ
High Angular Resolution Stellar Imaging with Occultations from the Cassini Spacecraft II: Kronocyclic Tomography
We present an advance in the use of Cassini observations of stellar
occultations by the rings of Saturn for stellar studies. Stewart et al. (2013)
demonstrated the potential use of such observations for measuring stellar
angular diameters. Here, we use these same observations, and tomographic
imaging reconstruction techniques, to produce two dimensional images of complex
stellar systems. We detail the determination of the basic observational
reference frame. A technique for recovering model-independent brightness
profiles for data from each occulting edge is discussed, along with the
tomographic combination of these profiles to build an image of the source star.
Finally we demonstrate the technique with recovered images of the {\alpha}
Centauri binary system and the circumstellar environment of the evolved
late-type giant star, Mira.Comment: 8 pages, 8 figures, Accepted by MNRA
High Angular Resolution Mid-infrared Imaging of Young Stars in Orion BN/KL
We present Keck LWS images of the Orion BN/KL star forming region obtained in
the first multi-wavelength study to have 0.3-0.5" resolution from 4.7 to 22
microns. The young stellar objects designated infrared source-n and radio
source-I are believed to dominate the BN/KL region. We have detected extended
emission from a probable accretion disk around source-n but infer a stellar
luminosity on the order of only 2000 Lsun. Although source-I is believed to be
more luminous, we do not detect an infrared counterpart even at the longest
wavelengths. However, we resolve the closeby infrared source, IRc2, into an arc
of knots ~1000 AU long at all wavelengths. Although the physical relation of
source-I to IRc2 remains ambiguous, we suggest these sources mark a high
density core (10^7-10^8 pc^-3 over 1000 AU) within the larger BN/KL star
forming cluster. The high density may be a consequence of the core being young
and heavily embedded. We suggest the energetics of the BN/KL region may be
dominated by this cluster core rather than one or two individual sources.Comment: 13 pages including 3 color figures. Accepted to The Astrophysical
Journal Letters pending slight reduction in length. High resolution figures
(jpeg) may be found at
http://cfa-www.harvard.edu/~lincoln/keck.bnkl.midir.ppr
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