Original article can be found at: http://www3.interscience.wiley.com Copyright Royal Astronomical SocietyWe present the discovery of fifteen new T2.5-T7.5 dwarfs (with estimated distances between 24???93pc), identified in the first three main data releases of the UKIRT Infrared Deep Sky Survey. This brings the total number of T dwarfs discovered in the Large Area Survey (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. (2006). 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 one of these new T dwarfs may be metal poor, three 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 consistent 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 and Malmquist bias, we estimate that there are 17??4 >T4 dwarfs in the J 619 volume of the LAS second data release. Comparing this to theoretical predictions is most consistent with a sub-stellar mass function exponent ?? between -1.0 and 0. This is consistent with the latest 2MASS/SDSS constraint (which is based on lower number statistics), and is significantly lower than the ?? 1.0 suggested by L dwarf field populations, possibly a result of the lower mass range probed by the T dwarf class

We present a new Subaru/HiCIAO high-contrast H-band polarized intensity (PI) image of a nearby transitional disk associated with TW Hydrae. The scattered light from the disk was detected from 0″ . 2 to 1″ . 5 (11-81 AU) and the PI image shows a clear axisymmetric depression in PI at ∼0″ . 4 (∼20 AU) from the central star, similar to the ∼80 AU gap previously reported from Hubble Space Telescope images. The azimuthal PI profile also shows that the disk beyond 0″ . 2 is almost axisymmetric. We discuss two possible scenarios explaining the origin of the PI depression: (1) a gap structure may exist at ∼20 AU from the central star because of a shallow slope seen in the PI profile, and (2) grain growth may be occurring in the inner region of the disk. Multi-band observations at nearinfrared and millimeter/submillimeter wavelengths play a complementary role in investigating dust opacity and may help reveal the origin of the gap more precisely.

Lighting designers have long accepted Kruithof's proposal that warm lighting is preferred over low intensities of illumination, and cool lighting is preferred over high intensities of illumination. However, when considering these preferences in color temperatures, Kruithof's proposal does not take into account seasonal changes or differences in age. Kakitsuba et al. (2000a, 2000b, 2003) demonstrated a seasonal change in color temperatures preferred by young Japanese subjects aged between 19 and 27 under illumination intensities of 200 lx and 1,500 lx, and an age difference in preferred color temperatures when the results were compared with those obtained for eight Japanese female subjects aged between 36 and 45 under an illumination intensity of 1,500 lx. Following these studies, the same middle-aged female subjects were exposed to 3,000 K and 7,500 K in controlled room temperatures of 22°C and 30°C. The illumination intensity was set at 200 lx on each occasion. Following controlled exposure for 30 min. at 25°C in a darkened room, subjects were exposed to given lighting and thermal conditions. Skin and oral temperatures, ECGs and blood pressures were measured throughout the exposures. At 15 min. intervals the subjects reported on comfort, calmness, brightness and thermal sensations. The resulting changes in HF values indicated that the subjects preferred 7,500 K to 3,000 K. This demonstrated that Kruithof's proposal could be accepted for middle-aged female subjects in the case of 200 lx as well as 1,500 lx.

Abstract. This paper discusses benchmark brown dwarfs in various environments, and focuses on those in wide binary systems. We present a summary of the recently discovered T dwarf population from the UKIDSS Large Area Survey, and describe the constraints that it places on our knowledge of the sub-stellar initial mass function. We also present some exciting results from our ongoing search for wide companions to this sample, that has so far revealed an M4-T8.5 binary system at ∼12 parsecs and also the first ever Tdwarf-white dwarf binary system. The T dwarfs in these binaries have their properties constrained by the primary object and are thus benchmark objects that are already testing the predictions of theoretical model atmospheres.