536 research outputs found

    A T8.5 Brown Dwarf Member of the Xi Ursae Majoris System

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    The Wide-field Infrared Survey Explorer has revealed a T8.5 brown dwarf (WISE J111838.70+312537.9) that exhibits common proper motion with a solar-neighborhood (8 pc) quadruple star system - Xi Ursae Majoris. The angular separation is 8.5 arc-min, and the projected physical separation is about 4000 AU. The sub-solar metallicity and low chromospheric activity of Xi UMa A argue that the system has an age of at least 2 Gyr. The infrared luminosity and color of the brown dwarf suggests the mass of this companion ranges between 14 and 38 Jupiter masses for system ages of 2 and 8 Gyr respectively.Comment: AJ in press, 12 pages LaTeX with 6 figures. More astrometric data and a laser guide star adaptive optics image adde

    Radiative Decay Modes of the D0D^{0} Meson

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    Using data recorded by the CLEO-II detector at CESR we have searched for four radiative decay modes of the D0D^0 meson: D0ϕγD^0\to\phi\gamma, D0ωγD^0\to\omega\gamma, D0KˉγD^0\to\bar{K}^{*}\gamma, and D0ρ0γD^0\to\rho^0\gamma. We obtain 90% CL upper limits on the branching ratios of these modes of 1.9×1041.9\times 10^{-4}, 2.4×1042.4\times 10^{-4}, 7.6×1047.6\times 10^{-4} and 2.4×1042.4\times 10^{-4} respectively.Comment: 15 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    The AllWISE Motion Survey and the Quest for Cold Subdwarfs

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    The AllWISE processing pipeline has measured motions for all objects detected on Wide-field Infrared Survey Explorer (WISE) images taken between 2010 January and 2011 February. In this paper, we discuss new capabilities made to the software pipeline in order to make motion measurements possible, and we characterize the resulting data products for use by future researchers. Using a stringent set of selection criteria, we find 22,445 objects that have significant AllWISE motions, of which 3525 have motions that can be independently confirmed from earlier Two Micron All Sky Survey (2MASS) images, yet lack any published motions in SIMBAD. Another 58 sources lack 2MASS counterparts and are presented as motion candidates only. Limited spectroscopic follow-up of this list has already revealed eight new L subdwarfs. These may provide the first hints of a "subdwarf gap" at mid-L types that would indicate the break between the stellar and substellar populations at low metallicities (i.e., old ages). Another object in the motion list—WISEA J154045.67–510139.3—is a bright (J ≈ 9 mag) object of type M6; both the spectrophotometric distance and a crude preliminary parallax place it ~6 pc from the Sun. We also compare our list of motion objects to the recently published list of 762 WISE motion objects from Luhman. While these first large motion studies with WISE data have been very successful in revealing previously overlooked nearby dwarfs, both studies missed objects that the other found, demonstrating that many other nearby objects likely await discovery in the AllWISE data products

    Complement C1 Esterase Inhibitor Levels Linked to Infections and Contaminated Heparin-Associated Adverse Events

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    Activation of kinin-kallikrein and complement pathways by oversulfated-chondroitin-sulfate (OSCS) has been linked with recent heparin-associated adverse clinical events. Given the fact that the majority of patients who received contaminated heparin did not experience an adverse event, it is of particular importance to determine the circumstances that increase the risk of a clinical reaction. In this study, we demonstrated by both the addition and affinity depletion of C1inh from normal human plasma, that the level of C1inh in the plasma has a great impact on the OSCS-induced kallikrein activity and its kinetics. OSCS-induced kallikrein activity was dramatically increased after C1inh was depleted, while the addition of C1inh completely attenuated kallikrein activity. In addition, actual clinical infection can lead to increased C1inh levels. Plasma from patients with sepsis had higher average levels of functional C1inh and decreased OSCS-induced kallikrein activity. Lastly, descriptive data on adverse event reports suggest cases likely to be associated with contaminated heparin are inversely correlated with infection. Our data suggest that low C1inh levels can be a risk factor and high levels can be protective. The identification of risk factors for contact system-mediated adverse events may allow for patient screening and clinical development of prophylaxis and treatments

    Nearby M, L, and T Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)

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    In our effort to complete the census of low-mass stars and brown dwarfs in the immediate solar neighborhood, we present spectra, photometry, proper motions, and distance estimates for 42 low-mass star and brown dwarf candidates discovered by the Wide-field Infrared Survey Explorer (WISE). We also present additional follow-up information on 12 candidates selected using WISE data but previously published elsewhere. The new discoveries include 15 M dwarfs, 17 L dwarfs, five T dwarfs, and five objects of other types. Among these discoveries is a newly identified “unusually red L dwarf” (WISE J223527.07 + 451140.9), four peculiar L dwarfs whose spectra are most readily explained as unresolved L + T binary systems, and a T9 dwarf (WISE J124309.61 + 844547.8). We also show that the recently discovered red L dwarf WISEP J004701.06 + 680352.1 may be a low-gravity object and hence young and potentially low-mass (< 25 M_(Jup))
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