The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5

We present Hubble Space Telescope (HST) near-infrared photometry of the coldest known brown dwarf, WISE J085510.83$-$071442.5 (WISE 0855$-$0714). WISE 0855$-$0714 was observed with the Wide Field Camera 3 (WFC3) aboard HST using the F105W, F125W, and F160W filters, which approximate the $Y$, $J$, and $H$ near-infrared bands. WISE 0855$-$0714 is undetected at F105W with a corresponding 2$\sigma$ magnitude limit of $\sim$26.9. We marginally detect WISE 0855$-$0714 in the F125W images (S/N $\sim$4), with a measured magnitude of 26.41 $\pm$ 0.27, more than a magnitude fainter than the $J-$band magnitude reported by Faherty and coworkers. WISE J0855$-$0714 is clearly detected in the F160W band, with a magnitude of 23.90 $\pm$ 0.02, the first secure detection of WISE 0855$-$0714 in the near-infrared. Based on these data, we find that WISE 0855$-$0714 has extremely red F105W$-$F125W and F125W$-$F160W colors relative to other known Y dwarfs. We find that when compared to the models of Saumon et al. and Morley et al., the F105W$-$F125W and F125W$-$F160W colors of WISE 0855$-$0714 cannot be accounted for simultaneously. These colors likely indicate that we are seeing the collapse of flux on the Wien tail for this extremely cold object.Comment: Accepted for publication in ApJ Letter

Near-Infrared Variability in the 2MASS Calibration Fields: A Search for Planetary Transit Candidates

The 2MASS photometric calibration observations cover ~6 square degrees on the sky in 35 "calibration fields" each sampled in nominal photometric conditions between 562 and 3692 times during the four years of the 2MASS mission. We compile a catalog of variables from the calibration observations to search for M dwarfs transited by extra-solar planets. We present our methods for measuring periodic and non-periodic flux variability. From 7554 sources with apparent Ks magnitudes between 5.6 and 16.1, we identify 247 variables, including extragalactic variables and 23 periodic variables. We have discovered three M dwarf eclipsing systems, including two candidates for transiting extrasolar planets.Comment: The Astrophysical Journal Supplement, in press; figures compresse

Investigation of aerothermodynamics and optical radiation in the AFE hypersonic flow field

Research for the radiation experiments on the Aeroassist Flight Experiment (AFE) was performed to obtain a data base for development of engineering requirements for aerobrakes. Due to funding restrictions, the necessary Aerobrake design data were obtained from ground based experiments, specifically arc-jet wind tunnels. Except for the instrument windows, final development of the AFE radiometers was completed. Window definition included several designs to be flight validated in arc-jets. This work was completed, and successful designs have evolved which will yield full scientific return from the flight experiment. The theoretical work includes final code development to describe the spacecraft environment to support instrument definition, optical radiation codes that operate at significantly improved speeds, and calculation of radiation forebody loads and effects on experiment objectives for varying AFE weights and trajectories. Furthermore, radiant flux vectors at the AFE base were predicted to be used for afterbody instrument definition. The Vacuum Ultraviolet Experiment for the Arc-Jet was completed, and arc-jet experiment conditions and experiment objectives were refined to incorporate the most current thinking. Ballistic range experiments were completed. Several shadowgraphs indicating corner turning angles and waviness structures were obtained, and the results were used to estimate the compression region location for the AFE flight. The waviness measured has helped to model the temporal variations of wake radiation for purposes of defining radiometers to measure the energy content of wake dynamics

SNIFFER WFD119: Enhancement of the River Invertebrate Classification Tool (RICT)

EXECUTIVE SUMMARY Project funders/partners: Environment Agency (EA), Northern Ireland Environment Agency (NIEA), Scotland & Northern Ireland Forum for Environmental Research (SNIFFER), Scottish Environment Protection Agency (SEPA) Background to research The Regulatory Agencies in the UK (the Environment Agency; Scottish Environment Protection Agency; and the Northern Ireland Environment Agency) now use the River Invertebrate Classification Tool (RICT) to classify the ecological quality of rivers for Water Framework Directive compliance monitoring. RICT incorporates RIVPACS IV predictive models and is a highly capable tool written in a modern software programming language. While RICT classifies waters for general degradation and organic pollution stress, producing assessments of status class and uncertainty, WFD compliance monitoring also requires the UK Agencies to assess the impacts of a wide range of pressures including hydromorphological and acidification stresses. Some of these pressures alter the predictor variables that current RIVPACS models use to derive predicted biotic indices. This project has sought to broaden the scope of RICT by developing one or more RIVPACS model(s) that do not use predictor variables that are affected by these stressors, but instead use alternative GIS based variables that are wholly independent of these pressures. This project has also included a review of the wide range of biotic indices now available in RICT, identifying published sources, examining index performance, and where necessary making recommendations on further needs for index testing and development. Objectives of research •To remove and derive alternative predictive variables that are not affected by stressors, with particular emphasis on hydrological/acidification metric predictors. •To construct one or more new RIVPACS model(s) using stressor independent variables. •Review WFD reporting indices notably AWIC(species), LIFE (species), PSI & WHPT. Key findings and recommendations : Predictor variables and intellectual property rights : An extensive suite of new variables have been derived by GIS for the RIVPACS reference sites that have been shown to act as stressor-independent predictor variables. These include measures of stream order, solid and drift geology, and a range of upstream catchment characteristics (e.g. catchment area, mean altitude of upstream catchment, and catchment aspect). It is recommended that decisions are reached on which of the newly derived model(s) are implemented in RICT so that IPR issues for the relevant datasets can be quickly resolved and the datasets licensed. It is also recommended that licensing is sought for a point and click system (where the dataset cannot be reverse engineered) that is capable of calculating any of the time-invariant RIVPACS environmental predictor variables used by any of the newly derived (and existing) RIVPACS models, and for any potential users. New stressor-independent RIVPACS models : Using the existing predictor variables, together with new ones derived for their properties of stressor-independence, initial step-wise forward selection discriminant models suggested a range of 36 possible models that merited further testing. Following further testing, the following models are recommended for assessing watercourses affected by flow/hydromorphological and/or acidity stress: • For flow/hydromorphological stressors that may have modified width, depth and/or substrate in GB, it is suggested that a new ‘RIVPACS IV – Hydromorphology Independent’ model (Model 24) is used (this does not use the predictor variables width, depth and substratum, but includes a suite of new stressor-independent variables). • For acidity related stressors in GB, it is suggested that a new ‘RIVPACS IV – Alkalinity Independent’ model (Model 35) is used (this does not use the predictor variable alkalinity, but includes new stressor-independent variables). • For flow/hydromorphological stressors and acidity related stressors in GB, it is suggested that a new ‘RIVPACS IV – Hydromorphology & Alkalinity Independent’ model (Model 13) is used (this does not use the predictor variables width, depth, substratum and alkalinity, but includes a suite of new stressor-independent variables). • Reduced availability of appropriate GIS tools at this time has meant that no new models have been developed for Northern Ireland. Discriminant functions and end group means have now been calculated to enable any of these models to be easily implemented in the RICT software. Biotic indices : The RIVPACS models in RICT can now produce expected values for a wide range of biotic indices addressing a variety of stressors. These indices will support the use of RICT as a primary tool for WFD classification and reporting of the quality of UK streams and rivers. There are however a number of outstanding issues with indices that need to be addressed: • There is a need to develop a biotic index for assessing metal pollution. • WFD EQR banding schemes are required for many of the indices to report what is considered an acceptable degree of stress (High-Good) and what is not (Moderate, Poor or Bad). • A comprehensive objective testing process needs to be undertaken on the indices in RICT using UK-wide, large-scale, independent test datasets to quantify their index-stressor relationships and their associated uncertainty, for example following the approach to acidity index testing in Murphy et al., (in review) or organic/general degradation indices in Banks & McFarland (2010). • Following objective testing, the UK Agencies should make efforts to address any index under-performance issues that have been identified, and where necessary new work should be commissioned to modify existing indices, or develop new ones where required so that indices for all stress types meet certain minimum performance criteria. • Testing needs to be done to examine index-stressor relationships with both observed index scores and RIVPACS observed/expected ratios. Work should also be done to compare the existing RIVPACS IV and the new stressor-independent models (developed in this project) as alternative sources of the expected index values for these tests. • Consideration should be given to assessing the extent to which chemical and biological monitoring points co-occur. Site-matched (rather than reach-matched) chemical and biological monitoring points would i) generate the substantial training datasets needed to refine or develop new indices and ii) generate the independent datasets for testing

Three New Cool Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer (WISE) and an Improved Spectrum of the Y0 Dwarf WISE J041022.71+150248.4

As part of a larger search of Wide-field Infrared Survey Explorer (WISE) data for cool brown dwarfs with effective temperatures less than 1000 K, we present the discovery of three new cool brown dwarfs with spectral types later than T7. Using low-resolution, near-infrared spectra obtained with the NASA Infrared Telescope Facility and the Hubble Space Telescope we derive spectral types of T9.5 for WISE J094305.98+360723.5, T8 for WISE J200050.19+362950.1, and Y0: for WISE J220905.73+271143.9. The identification of WISE J220905.73+271143.9 as a Y dwarf brings the total number of spectroscopically confirmed Y dwarfs to seventeen. In addition, we present an improved spectrum (i.e. higher signal-to-noise ratio) of the Y0 dwarf WISE J041022.71+150248.4 that confirms the Cushing et al. classification of Y0. Spectrophotometric distance estimates place all three new brown dwarfs at distances less than 12 pc, with WISE J200050.19+362950.1 lying at a distance of only 3.9-8.0 pc. Finally, we note that brown dwarfs like WISE J200050.19+362950.1 that lie in or near the Galactic plane offer an exciting opportunity to measure their mass via astrometric microlensing.Comment: Accepted for publication in the Astronomical Journa

WISE J163940.83-684738.6: A Y Dwarf identified by Methane Imaging

We have used methane imaging techniques to identify the near-infrared counterpart of the bright WISE source WISEJ163940.83-684738.6. The large proper motion of this source (around 3.0arcsec/yr) has moved it, since its original WISE identification, very close to a much brighter background star -- it currently lies within 1.5" of the J=14.90+-0.04 star 2MASS16394085-6847446. Observations in good seeing conditions using methane sensitive filters in the near-infrared J-band with the FourStar instrument on the Magellan 6.5m Baade telescope, however, have enabled us to detect a near-infrared counterpart. We have defined a photometric system for use with the FourStar J2 and J3 filters, and this photometry indicates strong methane absorption, which unequivocally identifies it as the source of the WISE flux. Using these imaging observations we were then able to steer this object down the slit of the FIRE spectrograph on a night of 0.6" seeing, and so obtain near-infrared spectroscopy confirming a Y0-Y0.5 spectral type. This is in line with the object's near-infrared-to-WISE J3--W2 colour. Preliminary astrometry using both WISE and FourStar data indicates a distance of 5.0+-0.5pc and a substantial tangential velocity of 73+-8km/s. WISEJ163940.83-684738.6 is the brightest confirmed Y dwarf in the WISE W2 passband and its distance measurement places it amongst the lowest luminosity sources detected to date.Comment: Accepted for publication in The Astrophysical Journal, 20 September 201

The 2MASS Wide-Field T Dwarf Search. IV Unting out T dwarfs with Methane Imaging

We present first results from a major program of methane filter photometry for low-mass stars and brown dwarfs. The definition of a new methane filter photometric system is described. A recipe is provided for the differential calibration of methane imaging data using existing 2MASS photometry. We show that these filters are effective in discriminating T dwarfs from other types of stars, and demonstrate this with Anglo-Australian Telescope observations using the IRIS2 imager. Methane imaging data and proper motions are presented for ten T dwarfs identified as part of the 2MASS "Wide Field T Dwarf Search" -- seven of them initially identified as T dwarfs using methane imaging. We also present near-infrared moderate resolution spectra for five T dwarfs, newly discovered by this technique. Spectral types obtained from these spectra are compared to those derived from both our methane filter observations, and spectral types derived by other observers. Finally, we suggest a range of future programs to which these filters are clearly well suited: the winnowing of T dwarf and Y dwarf candidate objects coming from the next generation of near-infrared sky surveys; the robust detection of candidate planetary-mass brown dwarfs in clusters; the detection of T dwarf companions to known L and T dwarfs via deep methane imaging; and the search for rotationally-modulated time-variable surface features on cool brown dwarfs.Comment: 20 pages. To appear in The Astronomical Journal, Nov. 200

Discovery of a High Proper Motion L Dwarf Binary: 2MASS J15200224-4422419AB

We report the discovery of the wide L1.5+L4.5 binary 2MASS J15200224-4422419AB, identified during spectroscopic followup of high proper motion sources selected from the Two Micron All Sky Survey. This source was independently identified by Kendall et al. in the SuperCOSMOS Sky Survey. Resolved JHK photometry and low resolution near-infrared spectroscopy demonstrate that this system is composed of two well-separated (1"174+/-0"016) L dwarfs. Component classifications are derived using both spectral ratios and comparison to near-infrared spectra of previously classified field L dwarfs. Physical association for the pair is deduced from the large (mu = 0"73+/-0"03 /yr) common proper motion of the components and their similar spectrophotometric distances (19+/-2 pc). The projected separation of the binary, 22+/-2 AU, is consistent with maximum separation/total system mass trends for very low mass binaries. The 2MASS J1520-4422 system exhibits both large tangential (66+/-7 km/s) and radial velocities (-70+/-18 km/s), and its motion in the local standard of rest suggests that it is an old member of the Galactic disk population. This system joins a growing list of well-separated (>0"5), very low mass binaries, and is an excellent target for resolved optical spectroscopy to constrain its age as well as trace activity/rotation trends near the hydrogen-burning limit.Comment: 35 pages, 8 figures; accepted for publication to ApJ; see also Kendall et al. astro-ph/060939

The prediction of flanking sound transmission below the critical frequency

Although reliable methods exist to predict the apparent sound reduction index of heavy, homogeneous isotopic building constructions, these methods are not appropriate for use with lightweight building constructions which typically have critical frequencies in or above the frequency range of interest. Three main methods have been proposed for extending the prediction of flanking sound transmission to frequencies below the critical frequency