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Deep search for companions to probable young brown dwarfs. VLT/NACO adaptive optics imaging using IR wavefront sensing

Chauvin, G. and Faherty, J. and Boccaletti, A. and Cruz, K. and Lagrange, A.-M. and Zuckerman, B. and Bessell, M. S. and Beuzit, J.-L. and Bonnefoy, M. and Dumas, C. and Lowrance, P. and Mouillet, D. and Song, I. (2012) Deep search for companions to probable young brown dwarfs. VLT/NACO adaptive optics imaging using IR wavefront sensing. Astronomy and Astrophysics, 548 . Art. No. A33. ISSN 0004-6361. doi:10.1051/0004-6361/201219446.

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Aims. We have obtained high contrast images of four nearby, faint, and very low mass objects 2MASS J04351455-1414468, SDSS J044337.61+000205.1, 2MASS J06085283-2753583 and 2MASS J06524851-5741376 (hereafter 2MASS0435-14, SDSS0443+00, 2MASS0608-27 and 2MASS0652-57), identified in the field as probable isolated young brown dwarfs. Our goal was to search for binary companions down to the planetary mass regime. Methods. We used the NAOS-CONICA adaptive optics instrument (NACO) and its unique capability to sense the wavefront in the near-infrared to acquire sharp images of the four systems in K_s, with a field of view of 28" x 28". Additional J and L' imaging and follow-up observations at a second epoch were obtained for 2MASS0652-57. Results. With a typical contrast ΔK_s = 4.0−7.0 mag, our observations are sensitive down to the planetary mass regime considering a minimum age of 10 to 120 Myr for these systems. No additional point sources are detected in the environment of 2MASS0435-14, SDSS0443+00 and 2MASS0608-27 between 0.1−12" (i.e. about 2 to 250 AU at 20 pc). 2MASS0652-57 is resolved as a ~230 mas binary. Follow-up observations reject a background contaminate, resolve the orbital motion of the pair, and confirm with high confidence that the system is physically bound. The J, K_s and L′ photometry suggest a q ~ 0.7−0.8 mass ratio binary with a probable semi-major axis of 5−6 AU. Among the four systems, 2MASS0652-57 is probably the less constrained in terms of age determination. Further analysis would be necessary to confirm its youth. It would then be interesting to determine its orbital and physical properties to derive the system’s dynamical mass and to test evolutionary model predictions.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Faherty, J.0000-0001-6251-0573
Boccaletti, A.0000-0001-9353-2724
Cruz, K.0000-0002-1821-0650
Bonnefoy, M.0000-0001-5579-5339
Lowrance, P.0000-0001-8014-0270
Song, I.0000-0002-5815-7372
Additional Information:© 2012 ESO. Article published by EDP Sciences. Received 19 April 2012; Accepted 14 August 2012. Published online 15 November 2012. Based on observations collected at the European Southern Observatory, Chile (ESO programmes 076.C-0554(A), 076.C-0554(B) and 085.C-0257(A). We thank Christine Ducourant, Rama Texeira and Joshua Schlieder for the useful discussion about the status of these young brown dwarf candidates and Alexis Brandeker for his remarks and suggestions as referee of this research note. We want to also thank the staff of ESO-VLT for their support at the telescope. This publication has made use of the SIMBAD and VizieR database operated at CDS, Strasbourg, France. Finally, we acknowledge support from the French National Research Agency (ANR) through project grant ANR10-BLANC0504-01 and the Programmes Nationaux de Planétologie et de Physique Stellaire (PNP & PNPS), in France.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)ANR10-BLANC0504-01
Programmes Nationaux de Planétologie et de Physique Stellaire (PNP & PNPS)UNSPECIFIED
Subject Keywords:brown dwarfs – binaries: close – instrumentation: adaptive optics – techniques: image processing
Record Number:CaltechAUTHORS:20130115-154903521
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36407
Deposited By: Tony Diaz
Deposited On:16 Jan 2013 19:42
Last Modified:09 Nov 2021 23:22

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