23,325 research outputs found

    Synthesis and thermal properties of strontium and calcium peroxides

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    A practical synthesis and a discussion of some chemical properties of pure strontium peroxide and calcium peroxide are presented. The general synthesis of these peroxides involves precipitation of their octahydrates by addition of H2O2 to aqueous ammoniacal Sr(NO3)2 or CaCl2. The octahydrates are converted to the anhydrous peroxides by various dehydration techniques. A new x-ray diffraction powder pattern for CaO2 x 8H2O is given from which lattice parameters a=6.212830 and c=11.0090 were calculated on the basis of the tetragonal crystal system

    Observation and Modeling of Coronal "Moss" With the EUV Imaging Spectrometer on Hinode

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    Observations of transition region emission in solar active regions represent a powerful tool for determining the properties of hot coronal loops. In this Letter we present the analysis of new observations of active region moss taken with the Extreme Ultraviolet Imaging Spectrometer (EIS) on the \textit{Hinode} mission. We find that the intensities predicted by steady, uniformly heated loop models are too intense relative to the observations, consistent with previous work. To bring the model into agreement with the observations a filling factor of about 16% is required. Furthermore, our analysis indicates that the filling factor in the moss is nonuniform and varies inversely with the loop pressure

    Technology utilization in a non-urban region - A measurement of the impact of the Technology Use Studies Center Final report

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    Technology utilization in agricultural areas and measurement of impact of technology use studies cente

    Astronomical Data Center Bulletin, volume 1, number 3

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    A catalog of galactic O-type stars, a machine-readable version of the bright star catalog, a two-micron sky survey, sky survey sources with problematical Durchmusterung identifications, data retrieval for visual binary stars, faint blue objects, the sixth catalog of galactic Wolf-Rayet stars, declination versus magnitude distribution, the SAO-HD-GC-DM cross index catalog, star cross-identification tables, astronomical sources, bibliographical star index search updates, DO-HD and HD-DO cross indices, and catalogs, are reviewed

    Astronomical Data Center Bulletin, volume 1, no. 1

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    Information about work in progress on astronomical catalogs is presented. In addition to progress reports, an upadated status list for astronomical catalogs available at the Astronomical Data Center is included. Papers from observatories and individuals involved with astronomical data are also presented

    Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode

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    Previous solar observations have shown that coronal loops near 1 MK are difficult to reconcile with simple heating models. These loops have lifetimes that are long relative to a radiative cooling time, suggesting quasi-steady heating. The electron densities in these loops, however, are too high to be consistent with thermodynamic equilibrium. Models proposed to explain these properties generally rely on the existence of smaller scale filaments within the loop that are in various stages of heating and cooling. Such a framework implies that there should be a distribution of temperatures within a coronal loop. In this paper we analyze new observations from the EUV Imaging Spectrometer (EIS) on \textit{Hinode}. EIS is capable of observing active regions over a wide range of temperatures (\ion{Fe}{8}--\ion{Fe}{17}) at relatively high spatial resolution (1\arcsec). We find that most isolated coronal loops that are bright in \ion{Fe}{12} generally have very narrow temperature distributions (σT≲3×105\sigma_T \lesssim 3\times10^5 K), but are not isothermal. We also derive volumetric filling factors in these loops of approximately 10%. Both results lend support to the filament models.Comment: Submitted to ApJ
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