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D. J. Pinfield,
B. Burningham,
M. Tamura,
S. K. Leggett,
N. Lodieu,
P. W. Lucas,
D. J. Mortlock,
S. J. Warren,
D. Homeier,
M. Ishii, [......],
S. L. Casewell,
K. Chiu,
G. Chabrier,
F. Clarke,
S. T. Hodgkin,
A. Magazzù,
M. J. McCaughrean, T. Nakajima,
Y. Pavlenko,
C. G. Tinney
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ABSTRACT: We present the discovery of 15 new T2.5–T7.5 dwarfs (with estimated distances ∼24–93 pc), identified in the first three main data releases of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey. This brings the total number of T dwarfs discovered in the Large Area Survey (LAS) (to date) to 28. These discoveries are confirmed by near-infrared spectroscopy, from which we derive spectral types on the unified scheme of Burgasser et al. Seven of the new T dwarfs have spectral types of T2.5–T4.5, five have spectral types of T5–T5.5, one is a T6.5p and two are T7–7.5. We assess spectral morphology and colours to identify T dwarfs in our sample that may have non-typical physical properties (by comparison to solar neighbourhood populations), and find that three of these new T dwarfs may have unusual metallicity, two may have low surface gravity, and one may have high surface gravity. The colours of the full sample of LAS T dwarfs show a possible trend to bluer Y−J with decreasing effective temperature, and some interesting colour changes in J−H and z−J (deserving further investigation) beyond T8. The LAS T dwarf sample from the first and second main data releases show good evidence for a good level of completion to J= 19. By accounting for the main sources of incompleteness (selection, follow-up and spatial) as well as the effects of unresolved binarity, Malmquist and Eddington bias, we estimate that there are 17 ± 4 ≥ T 4 dwarfs in the J≤ 19 volume of the LAS second data release. This value is most consistent with theoretical predictions if the substellar mass function exponent α (dN/dm∝m−α) lies between −1.0 and 0. This is consistent with the latest 2-Micron All Sky Survey (2MASS)/Sloan Digital Sky Survey (SDSS) constraint (which is based on lower number statistics) and is significantly lower than the α∼ 1.0 suggested by L dwarf field populations, which is possibly a result of the lower mass range probed by the T dwarf class.
Monthly Notices of the Royal Astronomical Society 10/2008; 390(1):304 - 322. · 4.90 Impact Factor
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N. Lodieu,
D. J. Pinfield,
S. K. Leggett,
R. F. Jameson,
D. J. Mortlock,
S. J. Warren,
B. Burningham,
P. W. Lucas,
K. Chiu,
M. C. Liu, [......],
H. R. A. Jones,
T. R. Kendall,
A. Magazzù,
E. L. Martín,
M. J. McCaughrean, T. Nakajima,
Y. Pavlenko,
M. Tamura,
C. G. Tinney,
M. R. Zapatero Osorio
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ABSTRACT: We present eight new T4.5–T7.5 dwarfs identified in the UKIRT (United Kingdom Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) Data Release 1 (DR1). In addition we have recovered the T4.5 dwarf SDSS J020742.91+000056.2 and the T8.5 dwarf ULAS J003402.77−005206.7. Photometric candidates were picked up in two-colour diagrams over 190 deg2 (DR1) and selected in at least two filters. All candidates exhibit near-infrared spectra with strong methane and water absorption bands characteristic of T dwarfs and the derived spectral types follow the unified scheme of Burgasser et al.. We have found six new T4.5–T5.5 dwarfs, one T7 dwarf, one T7.5 dwarf and recovered a T4.5 dwarf and a T8.5 dwarf. We provide distance estimates which lie in the 15–85 pc range; the T7.5 and T8.5 dwarfs are probably within 25 pc of the Sun. We conclude with a discussion of the number of T dwarfs expected after completion of the LAS, comparing these initial results to theoretical simulations.
Monthly Notices of the Royal Astronomical Society 08/2007; 379(4):1423 - 1430. · 4.90 Impact Factor
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ABSTRACT: We report four typical cases of a strangulated trapdoor type, blow-out fracture of the orbital floor in children under the age of 10years. Diplopia and restricted eye movement were observed soon after the accident, and surgical interventions were performed approximately within 2weeks from the impact in all four cases. Close intraoperative observations revealed all the fractures to be trapdoor-like, with the hinge located medially and the door bounded by a bony defect of a few millimetres wide along the infraorbital groove and two fracture lines in a coronal direction running from the groove, perpendicularly and medially. Furthermore, we found strangulation of soft tissue in the fracture line along the infraorbital groove. We believe that this type of fracture occurs due to the premature development of the orbit in children. All children were surgically treated with release of the trapped orbital tissue, but recovery of ocular movement required 2 to 3months. Consensus has it that early operation is favourable for this type of fracture. However our cases show that favourable results can be attained by operation done even after 2weeks. Understanding of the bony structure and the fracture pattern of the orbit in children will help in the accurate imaging diagnosis and selection of operative procedures.
European Journal of Plastic Surgery 03/2004; 27(1):12-19.
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ABSTRACT: Growth of an arbitrarily shaped dent made on a filament of power law and Maxwell type fluids being uniaxially extended was analysed in the Lagrangian coordinate assuming inertia, surface tension, gravity and air drag forces to be negligible in comparison to the rheological force.The use of the Lagrangian coordinate reduced the problem essentially into that of the extension of a uniform fluid cylinder thereby leading to a simple and straightforward solution of the nonlinear governing equations. An analytical solution was obtained with power law fluids. Within the context of the present dent growth problem the above nonlinear solution was so simple and clearcut that recource to the linearized perturbation method was totally unnecessary.Das Wachstum einer beliebig geformten Kerbe in einem Spinnfaden bei der einachsigen Verstreckung wird fr eine Potenz-Gesetz-Flssigkeit und eine Maxwell-Flssigkeit berechnet. Dabei wird ein Lagrangesches Koordinatensystem gewhlt, und es werden Trgheits-, Oberflchenspannungs-, Gravitations-und Luftreibungseffekte vernachlssigt.Die Verwendung Lagrangescher Koordinaten reduziert das Problem wesentlich auf dasjenige der Dehnung eines gleichmigen Flssigkeitszylinders und fhrt daher auf eine einfache und direkte Lsung der das Problem bestimmenden nicht-linearen Gleichungen. Fr Potenz-Gesetz-Flssigkeiten werden auf diese Weise analytische Lsungen gefunden. Wegen der Einfachheit des Problems braucht in dieser Darstellung nirgends auf linearisierte Strungsmethoden zurckgegriffen zu werden.
Rheologica Acta 10/1980; 19(6):698-709. · 2.03 Impact Factor
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T. R. Kendall,
M Tamura,
C. G. Tinney,
E. L. Martín,
M Ishii,
D. J. Pinfield,
P. W. Lucas,
H. R. A. Jones,
S. K. Leggett,
S. Dye, [......],
N. C. Hambly,
S. T. Hodgkin, T Nakajima,
R. F. Jameson,
N. Lodieu,
A. Magazzù,
M. J. McCaughrean,
Y. V. Pavlenko,
N. Tadashi,
M. R. Zapatero Osorio
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ABSTRACT: Context.We report on the first ultracool dwarf discoveries from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey Early Data Release (LAS EDR), in particular the discovery of T dwarfs which are fainter and more distant than those found using the 2MASS and SDSS surveys.Aims.We aim to show that our methodologies for searching the ~27 deg$^2$ of the LAS EDR are successful for finding both L and T dwarfs via cross-correlation with the Sloan Digital Sky Survey (SDSS) DR4 release. While the area searched so far is small, the numbers of objects found shows great promise for near-future releases of the LAS and great potential for finding large numbers of such dwarfs.Methods.Ultracool dwarfs are selected by combinations of their $\it YJH(K)$ UKIDSS colours and SDSS DR4 $z-J$ and $i-z$ colours, or, lower limits on these red optical/infrared colours in the case of DR4 dropouts. After passing visual inspection tests, candidates have been followed up by methane imaging and spectroscopy at 4 m and 8 m-class facilities.Results.Our main result is the discovery following CH$_4$ imaging and spectroscopy of a T4.5 dwarf, ULAS J 1452+0655, lying ~80 pc distant. A further T dwarf candidate, ULAS J 1301+0023, has very similar CH$_4$ colours but has not yet been confirmed spectroscopically. We also report on the identification of a brighter L0 dwarf, and on the selection of a list of LAS objects designed to probe for T-like dwarfs to the survey $J$-band limit.Conclusions.Our findings indicate that the combination of the UKIDSS LAS and SDSS surveys provide an excellent tool for identifying L and T dwarfs down to much fainter limits than previously possible. Our discovery of one confirmed and one probable T dwarf in the EDR is consistent with expectations from the previously measured T dwarf density on the sky.
http://dx.doi.org/10.1051/0004-6361:20066403.
