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Properties of the solar neighbor WISE J072003.20−084651.2

Ivanov, V. D. and Vaisanen, P. and Kniazev, A. Y. and Beletsky, Y. and Mamajek, E. E. and Mužic, K. and Beamín, J. C. and Boffin, H. M. J. and Pourbaix, D. and Gandhi, P. and Gulbis, A. and Monaco, L. and Saviane, I. and Kurtev, R. and Mawet, D. and Borissova, J. and Minniti, Dante (2015) Properties of the solar neighbor WISE J072003.20−084651.2. Astronomy and Astrophysics, 574 . Art. No. A64. ISSN 0004-6361.

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Context. The severe crowding towards the Galactic plane suggests that the census of nearby stars in that direction may be incomplete. Recently, Scholz reported a new M9 object at an estimated distance d ≃ 7 pc (WISE J072003.20−084651.2; hereafter WISE J0720) at Galactic latitude b = 2.3°. Aims. Our goals are to determine the physical characteristics of WISE J0720, its kinematic properties, and to address the question of whether it is a binary object, as was suggested in the discovery paper. Methods. Optical and infrared spectroscopy from the Southern African Large Telescope and Magellan, respectively, and spectral energy distribution fitting were used to determine the spectral type of WISE J0720. The measured radial velocity, proper motion, and parallax yielded its Galactic velocities. We also investigated if WISE J0720 may show X-ray activity based on archival data. Results. Our spectra are consistent with spectral type L0±1. We find no evidence for binarity, apart from a minor 2σ level difference in the radial velocities taken at two different epochs. The spatial velocity of WISE J0720 does not connect it to any known moving group; instead, it places the object with high probability in the old thin disk or in the thick disk. The spectral energy distribution fit hints at excess in the 12 μm and 22 μm WISE bands which may be due to a redder companion, but the same excess is visible in other late-type objects, and it more likely implies a shortcoming of the models (e.g., problems with the effective wavelengths of the filters for these extremely cool objects, etc.) rather than a disk or redder companion. The optical spectrum shows some Hα emission, indicative of stellar activity. Archival X-ray observations yield no detection. Conclusions. WISE J0720 is a new member of the solar neighborhood, the third nearest L dwarf. Our data do not support the hypothesis of its binary nature.

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Gandhi, P.0000-0003-3105-2615
Mawet, D.0000-0002-8895-4735
Additional Information:© 2015 ESO. Received: 30 August 2014; Accepted: 24 October 2014. Some observations reported in this paper were obtained with the Southern African Large Telescope (SALT). Some observations reported in this paper were obtained with the ESO New Technology Telescope under program 60.A-9700. All SAAO and SALT co-authors acknowledge the support from the National Research Foundation (NRF) of South Africa.We acknowledge support from the FONDAP Center for Astrophysics 15010003; BASAL CATA Center for Astrophysics and Associated Technologies PFB-06; the Ministry for the Economy, Development, and Tourisms Programa Inicativa Cientifica Milenio through grant IC 12009, awarded to The Millennium Institute of Astrophysics (MAS); FONDECYT grants No. 1090213, 1130196, and 1110326 from CONICYT, and the European Southern Observatory. J.C.B. acknowledge support from a Ph.D. Fellowship from CONICYT. R.K. acknowledges partial support from FONDECYT through grant 1130140. J.B. acknowledges support from FONDECYT No. 1120601; P.G. thanks STFC for support (grant reference ST/J003697/1). We have also made extensive use of the SIMBAD Database at CDS Strasbourg, of the 2MASS, which is a joint project of the University of Massachusetts and IPAC/CALTECH, funded by NASA and NSF, and of the VizieR catalogue access tool, CDS, Strasbourg, France. Based on data from CMC15 Data Access Service at CAB (INTA-CSIC). We thanks the anonymous referee for suggestions that helped to improve the paper.
Funding AgencyGrant Number
National Research Foundation (NRF) of South AfricaUNSPECIFIED
FONDAP Center for Astrophysics 15010003
BASAL CATA Center for Astrophysics and Associated TechnologiesPFB-06
Ministry for the Economy, Development, and Tourisms Programa Inicativa Cientifica MilenioIC 12009
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1090213
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1130196
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)1110326
European Southern ObservatoryUNSPECIFIED
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1130140
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1120601
Science and Technology Facilities Council (STFC)ST/J003697/1
Subject Keywords:stars: distances; solar neighborhood; stars: low-mass; stars: individual: WISE J072003.20; 84651.2; proper motions; stars: individual: 2MASS J07200708; 0845589
Record Number:CaltechAUTHORS:20150529-101522107
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Official Citation:V. D. Ivanov, P. Vaisanen, A. Y. Kniazev, Y. Beletsky, E. E. Mamajek, K. Mužić, J. C. Beamín, H. M. J. Boffin, D. Pourbaix, P. Gandhi, A. Gulbis, L. Monaco, I. Saviane, R. Kurtev, D. Mawet, J. Borissova and D. Minniti A&A 574 A64 (2015) DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57897
Deposited By: Jason Perez
Deposited On:01 Jun 2015 22:11
Last Modified:21 Mar 2019 19:00

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