Hip 63510C, Hip 73786B, and nine new isolated high proper motion T dwarf candidates from UKIDSS DR6 and SDSS DR7

Abstract

Aims: Completing the poorly known substellar census of the solar neighbourhood, especially with respect to the coolest brown dwarfs, will lead to a better understanding of failed star formation processes and binary statistics with different environmental conditions. Methods: Using UKIDSS data and their cross-correlation with the SDSS, we searched for high proper motion mid- to late-T dwarf candidates with extremely blue near-infrared (J-K<0) and very red optical-to-near-infrared (z-J>+2.5) colours. Results: With 11 newly found T dwarf candidates, the proper motions of which range between 100 and 800 mas/yr, we increased the number of UKIDSS T dwarf discoveries by $\approx$30%. Large proper motions were also measured for six of eight previously known T4.5-T9 dwarfs detected in our survey. All new candidates can be classified as T5-T9 dwarfs based on their colours. Two of these objects were found to be common proper motion companions of Hipparcos stars with accurate parallaxes. The latter allow us to determine absolute magnitudes from which we classify Hip 63510C as T7 and Hip 73786B as T6.5 dwarfs with an uncertainty of $\pm$1 spectral subtype. The projected physical separation from their low-mass (M0.5 and K5) primaries is in both cases about 1200 AU. One of the Hipparcos stars has already a known very low-mass star or brown dwarf companion on a close astrometric orbit (Hip 63510B = Gl 494B). With distances of only 11.7 and 18.6 pc, deduced from their primaries respectively for Hip 63510C and Hip 73786B, various follow-up observations can easily be carried out to study these cool brown dwarfs in more detail and to compare their properties with those of the already well-investigated primaries.

improved and extended version accepted by Astronomy and Astrophysics (text and references added, revised accuracies of proper motions and spectral types, new Table 7, extended Fig.3)

References in corpus (14)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The WFCAM Science Archive
• Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters
• The UKIRT Infrared Deep Sky Survey Early Data Release
• Mid-Infrared Photometry of Cold Brown Dwarfs: Diversity in Age, Mass and Metallicity
• Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including a Possible L/T Transition Binary
• CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition?
• A very cool brown dwarf in UKIDSS DR1
• The discovery of an M4+T8.5 binary system
• Exploring the substellar temperature regime down to ~550K
• Fifteen new T dwarfs discovered in the UKIDSS Large Area Survey
• Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results
• Ca II H and K Chromospheric Emission Lines in Late K and M Dwarfs
• GTC Osiris spectroscopic identification of a faint L subdwarf in the UKIRT Infrared Deep Sky Survey

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• The Hawaii Infrared Parallax Program. IV. A Comprehensive Parallax Survey of L0-T8 dwarfs with UKIRT
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• NPARSEC: NTT Parallaxes of Southern Extremely Cool objects. Goals, targets, procedures and first results
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• New M, L, and T Dwarf Companions to Nearby Stars from the Wide-field Infrared Survey Explorer
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• UKIDSS detections of cool brown dwarfs - proper motions of 14 known $>$T5 dwarfs and discovery of three new T5.5-T6 dwarfs
• Planets Around Low-Mass Stars (PALMS). II. A Low-Mass Companion to the Young M Dwarf GJ 3629 Separated By 0.2"
• USco1621 B and USco1556 B: Two wide companions at the deuterium-burning mass limit in Upper Scorpius
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• Combining Hipparcos and Gaia data for the study of binaries: the BINARYS tool
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• Statistical Study of 2XMMi-DR3/SDSS-DR8 Cross-correlation Sample
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• CFBDS J111807-064016: A new L/T transition brown dwarf in a binary system
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