AOP Armagh Observatory and Planetarium Open Repository

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The Armagh Observatory and Planetarium research repository provides internationally-recognised research in astronomy and related sciences. 

 

  • Diagnosing transient plasma status: from solar atmosphere to tokamak divertor

    RAL Space, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, U.K.; Department of Physics, University of Strathlyde, 107 Rottenrow, Glasgow G4 0NG, U.K.; Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB, U.K.; Armagh Observatory, College Hill, Armagh BT61 9DG, U.K.; Giunta, A. S.; Henderson, S.; O'Mullane, M.; Harrison, J.; Doyle, J. G.; Summers, H. P. (Journal of Instrumentation, 2016-09-01)
    This work strongly exploits the interdisciplinary links between astrophysical (such as the solar upper atmosphere) and laboratory plasmas (such as tokamak devices) by sharing the development of a common modelling for time-dependent ionisation. This is applied to the interpretation of solar flare data observed by the UVSP (Ultraviolet Spectrometer and Polarimeter), on-board the Solar Maximum Mission and the IRIS (Interface Region Imaging Spectrograph), and also to data from B2-SOLPS (Scrape Off Layer Plasma Simulations) for MAST (Mega Ampère Spherical Tokamak) Super-X divertor upgrade. The derived atomic data, calculated in the framework of the ADAS (Atomic Data and Analysis Structure) project, allow equivalent prediction in non-stationary transport regimes and transients of both the solar atmosphere and tokamak divertors, except that the tokamak evolution is about one thousand times faster.
  • HST spectroscopy of chemically peculiar hot subdwarfs: PG 0909+276 and UVO0512-08

    Armagh Observatory and Planetarium, N. Ireland and University of Shefleld, Department of Astrophysics, Shefleld, UK; Wild, James; Jeffery, Christopher Simon (Open Astronomy, 2017-12-01)
    High-resolution ultraviolet spectroscopy of two chemically peculiar hot subdwarfs, PG 0909+276 and UVO0512-08, has been obtained using the Hubble Space Telescope. Chemical abundances in the stars' atmospheres were measured from previous optical spectra and from the new ultraviolet observations. Iron-group metals, including cobalt, copper and zinc, are highly enriched relative to typical subdwarf B (sdB) stars. Lead is also enriched, but with an abundance similar to other sdB stars. The surface chemistry of these two stars is quite distinct from both hydrogen-rich normal sdB stars and also from the intermediate helium-rich sdB stars which show heavy-element superabundances. A full explanation for exotic chemistries in hot subdwarfs remains elusive.
  • New Intense Multiband Photometric Observations of the Hot Carbon Star V348 Sagittarii (Abstract)

    Oude Bleken 12, Mol 2400, Belgium; Armagh Observatory, College Hill, Armagh BT61 9DG, United Kingdom; Hambsch, F.; Jeffery, C. S. (Journal of the American Association of Variable Star Observers (JAAVSO), 2019-06-01)
    (Abstract only) V348 Sgr is one of four hot carbon-rich and hydrogen-deficient stars. It is also the central star of a planetary nebula with a strong stellar wind, an infrared dust excess, and a circumstellar dust shell. Since July 2014, near daily multi-band photometric observations have been obtained at the Remote Observatory Atacama Desert (ROAD) close to San Pedro de Atacama, Chile. Strong variations of the brightness of V348 Sgr have been observed, ranging from magnitude 19 to 11.2 in V band. No clear periodicity is discernible in the data. The observed light curve shows much more variation and on a much shorter time scale than that of R CrB, the prototype hydrogen deficient, carbon- and helium-rich star. The star becomes markedly redder during extinction phases as a consequence of obscuring dust. The particular challenge in this case is to understand what triggers the production of dust.
  • LS IV — 14°116 : A Time-Resolved Spectroscopic Study

    Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK. School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland; Martin, Pamela; Jeffery, C. Simon (Open Astronomy, 2017-12-01)
    LSIV-14 116 is a very unusual subdwarf B star. It pulsates non-radially with high-order g-modes, these pulsations are unexpected and unexplained, as the effective temperature is 6 000K hotter than the blue edge of the hot subdwarf g-mode instability strip. Its spectrum is enriched in helium which is not seen in either the V361 Hya (p-mode pulsators) or the V1093 Her stars (g-mode pulsators). Even more unusual is the 4 dex overabundance of zirconium, yttrium, and strontium. It is proposed that these over-abundances are a result of extreme chemical stratification driven by radiative levitation. We have over 20hrs of VLT/UVES spectroscopy from which we have obtained radial velocity curves for individual absorption lines. We are currently exploring ways in which to resolve the photospheric motion as a function of optical depth.
  • A review of seismic observations of Kepler and K2-Observed sdBV stars

    Department of Physics, Astronomy and Materials Science, Missouri StateUniversity, United States of America; Department of Physics, Astronomy and Materials Science, Missouri StateUniversity, United States of America; Suhora Observatory and Krakow Pedagogical University,Krakow, Poland; Nordic Optical Telescope,Santa Cruz de Tenerife, Spain; Armagh Observatory and Planetarium,Armagh, Ireland; Reed, Michael D.; Baran, Andrzej S.; Telting, John H.; Østensen, Roy H.; Jeffery, Christopher S.; Kern, Joshua W.; et al. (Open Astronomy, 2018-07-01)
    This paper reviews recent seismic findings from Kepler and K2 data. Using three years of short cadence Kepler (K1) data, it is possible to examine time evolution of pulsations in an unprecedented way. While K2 observations are shorter, only three months, they are important as they are finding more sdBV stars than K1 did. Most importantly, K2 is discovering more p-mode pulsators with coverage not possible to get from the ground.

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