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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 421665.0, MPI für Astronomie / Publikationen_mpia
Mid-infrared imaging of brown dwarfs in binary systems
Authors:Geißler, K.; Chauvin, G.; Sterzik, M. F.
Date of Publication (YYYY-MM-DD):2008
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:A&A
Start Page:193
End Page:198
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Context: Brown dwarfs exhibit complex atmospheric signatures, and their properties are highly sensitive to effective temperature, surface gravity, and metallicity. Several physical properties of brown dwarfs in binary systems can be well inferred from the primary, and therefore allow one to better constrain their atmospheres. Aims: We want to constrain atmospheric models of brown dwarfs in binary systems using narrow-band mid-infrared photometry. Methods: High spatial resolution and sensitivity is required to resolve the components. Therefore we have obtained deep mid-infrared images of four close binary systems with brown dwarf companions using VISIR at the Very Large Telescope (VLT) in three narrow-band filters at 8.6, 10.5 and 11.25 mum. Results: Three brown dwarf companions (GJ 229 B, HD 130948 BC and HR 7329 B) were detected at 8.6 mum. HD 130948 BC was also observed at 10.5 mum. Finally, we establish upper flux limits for the other narrow band filters with null detections. Conclusions: Our results, are in general, compatible with previous observations and model expectations for these objects. For HD 130948 BC, we conclude that there is photometric variability on a significance level of 2.8sigma based on repeated observations. The bandpass around 10.5 mum appears specifically well suited for variability studies, and we speculate that either inhomogeneities in the atmospheric NH3 distribution, or silicate absorption, might cause its time-variability. Based on observations made with ESO Telescopes at the Paranal Observatories under programme IDs 076.C-0556(A) and 077.C-0438(A).
Free Keywords:stars: low-mass; brown dwarfs; stars: fundamental parameters
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2008A%26A...480..193... [ID No:1]
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