1,522 research outputs found

    Common-Resolution Convolution Kernels for Space- and Ground-Based Telescopes

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    Multi-wavelength study of extended astronomical objects requires combining images from instruments with differing point spread functions (PSFs). We describe the construction of convolution kernels that allow one to generate (multi-wavelength) images with a common PSF, thus preserving the colors of the astronomical sources. We generate convolution kernels for the cameras of the Spitzer Space Telescope, Herschel Space Observatory, Galaxy Evolution Explorer (GALEX), Wide-field Infrared Survey Explorer (WISE), ground-based optical telescopes (Moffat functions and sum of Gaussians), and Gaussian PSFs. These kernels allow the study of the Spectral Energy Distribution (SED) of extended objects, preserving the characteristic SED in each pixel. The convolution kernels and the IDL packages used to construct and use them are made publicly available

    Inverse perturbation method for structural redesign with frequency and mode shape constraints

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76581/1/AIAA-8777-705.pd

    The Liking Gap in Conversations: Do People Like Us More Than We Think?

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    Having conversations with new people is an important and rewarding part of social life. Yet conversations can also be intimidating and anxiety provoking, and this makes people wonder and worry about what their conversation partners really think of them. Are people accurate in their estimates? We found that following interactions, people systematically underestimated how much their conversation partners liked them and enjoyed their company, an illusion we call the liking gap. We observed the liking gap as strangers got acquainted in the laboratory, as first-year college students got to know their dorm mates, and as formerly unacquainted members of the general public got to know each other during a personal development workshop. The liking gap persisted in conversations of varying lengths and even lasted for several months, as college dorm mates developed new relationships. Our studies suggest that after people have conversations, they are liked more than they know

    Scientific Visualization Using the Flow Analysis Software Toolkit (FAST)

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    Over the past few years the Flow Analysis Software Toolkit (FAST) has matured into a useful tool for visualizing and analyzing scientific data on high-performance graphics workstations. Originally designed for visualizing the results of fluid dynamics research, FAST has demonstrated its flexibility by being used in several other areas of scientific research. These research areas include earth and space sciences, acid rain and ozone modelling, and automotive design, just to name a few. This paper describes the current status of FAST, including the basic concepts, architecture, existing functionality and features, and some of the known applications for which FAST is being used. A few of the applications, by both NASA and non-NASA agencies, are outlined in more detail. Described in the Outlines are the goals of each visualization project, the techniques or 'tricks' used lo produce the desired results, and custom modifications to FAST, if any, done to further enhance the analysis. Some of the future directions for FAST are also described

    Superfield algorithm for higher order gauge field theories

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    We propose an algorithm for the construction of higher order gauge field theories from a superfield formulation within the Batalin-Vilkovisky formalism. This is a generalization of the superfield algorithm recently considered by Batalin and Marnelius. This generalization seems to allow for non-topological gauge field theories as well as alternative representations of topological ones. A five dimensional non-abelian Chern-Simons theory and a topological Yang-Mills theory are treated as examples.Comment: 17 pages in LaTeX, improved text, published versio

    Nonlinear inverse perturbation method in dynamic analysis

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76092/1/AIAA-8245-515.pd

    A Parallactic Distance of 389 +24/-21 parsecs to the Orion Nebula Cluster from Very Long Baseline Array Observations

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    We determine the parallax and proper motion of the flaring, non-thermal radio star GMR A, a member of the Orion Nebula Cluster, using Very Long Baseline Array observations. Based on the parallax, we measure a distance of 389 +24/-21 parsecs to the source. Our measurement places the Orion Nebula Cluster considerably closer than the canonical distance of 480 +/- 80 parsecs determined by Genzel et al. (1981). A change of this magnitude in distance lowers the luminosities of the stars in the cluster by a factor of ~ 1.5. We briefly discuss two effects of this change--an increase in the age spread of the pre-main sequence stars and better agreement between the zero-age main-sequence and the temperatures and luminosities of massive stars.Comment: 10 pages, 4 figures, emulateapj, accepted to Ap

    Dusty OB stars in the Small Magellanic Cloud - II: Extragalactic Disks or Examples of the Pleiades Phenomenon?

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    We use mid-infrared Spitzer spectroscopy and far-infrared Herschel photometry for a sample of twenty main sequence O9--B2 stars in the Small Magellanic Cloud (SMC) with strong 24 micron excesses to investigate the origin of the mid-IR emission. Either debris disks around the stars or illuminated patches of dense interstellar medium (ISM) can cause such mid-IR emission. In a companion paper, Paper I, we use optical spectroscopy to show that it is unlikely for any of these sources to be classical Be stars or Herbig Ae/Be stars. We focus our analysis on debris disks and cirrus hot spots. We find three out of twenty stars to be significantly extended in the mid-IR, establishing them as cirrus hot spots. We then fit the IR spectral energy distributions to determine dust temperatures and masses. We find the dust masses in the SMC stars to be larger than for any known debris disks, although this evidence against the debris disk hypothesis is circumstantial. Finally, we created a local comparison sample of bright mid-IR OB stars in the Milky Way (MW) by cross-matching the WISE and Hipparcos catalogs. All such local stars in the appropriate luminosity range that can be unambiguously classified are young stars with optical emission lines or are spatially resolved by WISE with sizes too large to be plausible debris disk candidates. We conclude that the very strong mid-IR flux excesses are most likely explained as cirrus hot spots, although we cannot rigorously rule out that a small fraction of the sample is made up of debris disks or transition disks. We present suggestive evidence that bow-shock heating around runaway stars may be a contributing mechanism to the interstellar emission. These sources, interpreted as cirrus hot spots, offer a new localised probe of diffuse interstellar dust in a low metallicity environment. (Abridged)Comment: Accepted for publication in ApJ, 23 pages, 11 figures, 8 table
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