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WISE J061213.85-303612.5: a new T-dwarf binary candidate

Huélamo, N. and Ivanov, V. D. and Kurtev, R. and Girard, J. H. and Borissova, J. and Mawet, D. and Mužic, K. and Cáceres, C. and Melo, C. H. F. and Sterzik, M. F. and Minniti, D. (2015) WISE J061213.85-303612.5: a new T-dwarf binary candidate. Astronomy and Astrophysics, 578 . Art. No. A1. ISSN 0004-6361. doi:10.1051/0004-6361/201525634.

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Context. T and Y dwarfs are among the coolest and least luminous objects detected, and they can help to understand the properties of giant planets. Up to now, there are more than 350 T dwarfs that have been identified thanks to large imaging surveys in the infrared, and their multiplicity properties can shed light on the formation process. Aims. The aim of this work is to look for companions around a sample of seven ultracoool objects. Most of them have been discovered by the WISE observatory and have not been studied before for multiplicity. Methods. We observed a sample six T dwarfs and one L9 dwarf with the Laser Guide Star (LGS) and NAOS-CONICA, the adaptive optics (AO) facility, and the near infrared camera at the ESO Very Large Telescope. We observed all the objects in one or more near-IR filters (JHK_s). Results. From the seven observed objects, we have identified a subarcsecond binary system, WISE J0612-3036, composed of two similar components with spectral types of T6. We measure a separation of ρ = 350 ± 5 mas and a position angle of PA = 235 ± 1°. Using the mean absolute magnitudes of T6 dwarfs in the 2MASS JHK_s bands, we estimate a distance of d = 31 ± 6 pc and derive a projected separation of ρ ~ 11 ± 2 au. Another target, WISE J2255-3118, shows a very faint object at 1.̋3 in the K_s image. The object is marginally detected in H, and we derive a near infrared color of H − Ks> 0.1 mag. HST/WFC3 public archival data reveals that the companion candidate is an extended source. Together with the derived color, this suggests that the source is most probably a background galaxy. The five other sources are apparently single, with 3-σ sensitivity limits between H = 19–21 for companions at separations ≥ 0.̋5. Conclusions. WISE 0612-3036 is probably a new T-dwarf binary composed of two T6 dwarfs. As in the case of other late T-dwarf binaries, it shows a mass ratio close to 1, although its projected separation, ~11 au, is larger than the average (~5 au). Additional observations are needed to confirm that the system is bound.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Huélamo, N.0000-0002-2711-8143
Girard, J. H.0000-0001-8627-0404
Borissova, J.0000-0002-5936-7718
Mawet, D.0000-0002-8895-4735
Minniti, D.0000-0002-7064-099X
Additional Information:© 2015 ESO. Article published by EDP Sciences. Received 9 January 2015; Accepted 24 March 2015; Published online 22 May 2015. This work used data collected at the VLT under runs 89.C-0494(A, B, C) and 91.C-0501(A, B). Based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA), and the Canadian Astronomy Data Centre (CADC/NRC/CSA). We thank the referee, C. Reyle, for her useful comments. This research has been funded by Spanish grants AYA2010-21161-C02-02 and AYA2012-38897-C02-01. Support for N.H., J.B., R.K., and D.M. is provided by the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. J.B. is supported by FONDECYT No.1120601, R.K. is supported by Fondecyt Reg. No. 1130140. D.M. is also supported by FONDECYT No.1130196 and by the Center for Astrophysics and Associated Technologies CATA PFB-06. C.C. acknowledges the support from project CONICYT FONDECYT Postdoctorado 3140592. We are indebted to the Paranal staff for their support during the runs. N.H. thanks H. Bouy for useful discussions. This research has benefited from the M, L, T, and Y dwarf compendium housed at
Funding AgencyGrant Number
Ministerio de Educación y Ciencia (MEC)AYA2010-21161-C02-02
Ministerio de Educación y Ciencia (MEC)AYA2012-38897-C02-01
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1120601
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1130140
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1130196
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3140592
Subject Keywords:brown dwarfs – binaries: visual – techniques: high angular resolution
Record Number:CaltechAUTHORS:20150519-093429110
Persistent URL:
Official Citation:WISE J061213.85-303612.5: a new T-dwarf binary candidate N. Huélamo, V. D. Ivanov, R. Kurtev, J. H. Girard, J. Borissova, D. Mawet, K. Mužić, C. Cáceres, C. H. F. Melo, M. F. Sterzik and D. Minniti A&A, 578 (2015) A1 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57646
Deposited On:19 May 2015 18:42
Last Modified:10 Nov 2021 21:53

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