40,470 research outputs found

    How to Make the Dream Come True: The Astronomers' Data Manifesto

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    Astronomy is one of the most data-intensive of the sciences. Data technology is accelerating the quality and effectiveness of its research, and the rate of astronomical discovery is higher than ever. As a result, many view astronomy as being in a 'Golden Age', and projects such as the Virtual Observatory are amongst the most ambitious data projects in any field of science. But these powerful tools will be impotent unless the data on which they operate are of matching quality. Astronomy, like other fields of science, therefore needs to establish and agree on a set of guiding principles for the management of astronomical data. To focus this process, we are constructing a 'data manifesto', which proposes guidelines to maximise the rate and cost-effectiveness of scientific discovery.Comment: Submitted to Data Science Journal Presented at CODATA, Beijing, October 200

    Bulk and Edge excitations in a ν=1\nu =1 quantum Hall ferromagnet

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    In this article, we shall focus on the collective dynamics of the fermions in a ν=1\nu = 1 quantum Hall droplet. Specifically, we propose to look at the quantum Hall ferromagnet. In this system, the electron spins are ordered in the ground state due to the exchange part of the Coulomb interaction and the Pauli exclusion principle. The low energy excitations are ferromagnetic magnons. To provide a means for describing these magnons, we shall discuss a method of introducing collective coordinates in the Hilbert space of many-fermion systems. These collective coordinates are bosonic in nature. They map a part of the fermionic Hilbert space into a bosonic Hilbert space. Using this technique, we shall interpret the magnons as bosonic collective ex citations in the Hilbert space of the many-electron Hall system. By considering a Hall droplet of finite extent, we shall also obtain the effective Lagrangian governing the spin collective excitations at the edge of the sample.Comment: Plain TeX 18 Pages Proceedings for the Y2K conference on strongly c orrelated fermionic systems, Calcutta, Indi

    X-ray and radio prompt emission from a hypernova SN 2002ap

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    Here we report on combined X-ray and radio observations of SN 2002ap with XMM-Newton ToO observation and GMRT observations aided with VLA published results. In deriving the X-ray flux of SN 2002ap we account for the contribution of a nearby source, found to be present in the pre-SN explosion images obtained with Chandra observatory. We also derive upper limits on mass loss rate from X-ray and radio data. We suggest that the prompt X-ray emission is non-thermal in nature and its is due to the repeated compton boosting of optical photons. We also compare SN's early radiospheric properties with two other SNe at the same epoch.Comment: 4 pages, 5 figures. Uses espcrc2.sty. To appear in proceedings of symposium on X-ray astronomy "The Restless High-Energy Universe", May 2003, Amsterdam, The Netherlands, eds. E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijer

    Comets in Australian Aboriginal Astronomy

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    We present 25 accounts of comets from 40 Australian Aboriginal communities, citing both supernatural perceptions of comets and historical accounts of bright comets. Historical and ethnographic descriptions include the Great Comets of 1843, 1861, 1901, 1910, and 1927. We describe the perceptions of comets in Aboriginal societies and show that they are typically associated with fear, death, omens, malevolent spirits, and evil magic, consistent with many cultures around the world. We also provide a list of words for comets in 16 different Aboriginal languages.Comment: Accepted in the "Journal for Astronomical History & Heritage", 17 Pages, 6 Figures, 1 Tabl

    "Bridging the Gap" through Australian Cultural Astronomy

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    For more than 50,000 years, Indigenous Australians have incorporated celestial events into their oral traditions and used the motions of celestial bodies for navigation, time-keeping, food economics, and social structure. In this paper, we explore the ways in which Aboriginal people made careful observations of the sky, measurements of celestial bodies, and incorporated astronomical events into complex oral traditions by searching for written records of time-keeping using celestial bodies, the use of rising and setting stars as indicators of special events, recorded observations of variable stars, the solar cycle, and lunar phases (including ocean tides and eclipses) in oral tradition, as well as astronomical measurements of the equinox, solstice, and cardinal points.Comment: Proceedings of IAU Symposium 278, Oxford IX International Symposium on Archaeoastronomy, International Society for Archaeoastronomy & Astronomy in Culture (ISAAC), held in Lima, Peru, 5-9 January 2011. 9 pages, 4 images, 1 table (Accepted
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