Now showing items 277-296 of 602

  • Harko, T.; Koivisto, Tomi Sebastian; Lobo, F. S. N.; Olmo, G. J. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)
    We present a novel approach to modified theories of gravity which consists of adding to the Einstein-Hilbert Lagrangian an f(R) term constructed à la Palatini. Using the respective dynamically equivalent scalar-tensor ...
  • Pagano, P.; Van Damme, H. J.; Antolin, Patrick; de Moortel, Ineke (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Context. Magnetohydrodynamic (MHD) waves are ubiquitous in the solar corona where the highly structured magnetic fields provide efficient wave guides for their propagation. While MHD waves have been observed originating ...
  • Drews, Ainar; Rouppe van der Voort, Luc (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Context. Penumbral microjets (PMJs) are short-lived jets found in the penumbra of sunspots, first observed in wide-band Ca ii H line observations as localized brightenings, and are thought to be caused by magnetic reconnection. ...
  • Loukitcheva, M.; Solanki, S. K.; Carlsson, Mats; White, S. M. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    Aims: We use advanced 3D non-local thermodynamic equilibrium radiative magnetohydrodynamic simulations of the solar atmosphere to carry out detailed tests of chromospheric diagnostics at millimeter and submillimeter ...
  • Loukitcheva, M.; White, S. M.; Solanki, S. K.; Fleishman, G. D.; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Aims. We use state-of-the-art, three-dimensional non-local thermodynamic equilibrium (non-LTE) radiative magnetohydrodynamic simulations of the quiet solar atmosphere to carry out detailed tests of chromospheric magnetic ...
  • Børve, Steinar; Sato, Hiroatsu; Pecseli, Hans; Trulsen, Jan Karsten (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2011)
    Oscillations with periods on the order of 5–10 min have been observed by instrumented spacecrafts in the Earth's magnetosphere. These oscillations often follow sudden impacts related to coronal mass ejections. It is ...
  • Gronke, Max Balthasar (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We compare 237 Lyman-α (Lyα) spectra of the MUSE-Wide survey to a suite of radiative transfer simulations consisting of a central luminous source within a concentric, moving shell of neutral gas, and dust. This six parameter ...
  • Kerr, Graham S.; Allred, Joel C.; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    The Interface Region Imaging Spectrograph has routinely observed the flaring Mg ii near-ultraviolet (NUV) spectrum, offering excellent diagnostic potential and a window into the location of energy deposition. A number of ...
  • Kerr, Graham S.; Carlsson, Mats; Allred, Joel C. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    To extract the information that the Mg ii NUV spectra (observed by the Interface Region Imaging Spectrograph) carry about the chromosphere during solar flares, and to validate models of energy transport via model–data ...
  • Zhu, Yingjie; Kowalski, Adam F.; Tian, Hui; Uitenbroek, Han; Carlsson, Mats; Allred, Joel C. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Observations from the Interface Region Imaging Spectrograph often reveal significantly broadened and non-reversed profiles of the Mg ii h, k and triplet lines at flare ribbons. To understand the formation of these optically ...
  • Voivodic, Rodrigo; Lima, Marcos; Llinares, Claudio; Mota, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    © 2017 American Physical Society
  • Bø, Iselin M Thomassen (Master thesis / Masteroppgave, 2008)
    Systematic anomalies that seem to follow the first ionisation potential (FIP) of the minor, heavy elements at the sun, have been found when comparing the observed elemental abundances in the upper solar atmosphere with the ...
  • Pucci, Stefano (Master thesis / Masteroppgave, 2008)
    In-situ observations together with spectroscopic measurements show that the elemental abundance in the solar atmosphere varies from the photosphere to solar wind. An enrichment for low First Ionisation Potential elements ...
  • Hodne, Espen (Master thesis / Masteroppgave, 2019)
    I calculate Lyman-α luminosity and surface brightness; and find that the values are much higher than typical for this kind of galaxy. I find this is due to very high star formation rate; which makes the galaxy superluminous.
  • Forero-Romero, J. E.; Gronke, Max Balthasar; Remolina-Gutiérrez, Maria Camila; Gravito-Camargo, Nicolás; Dijkstra, Mark (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    © 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
  • Svendsen, Øyvind Brynhildsvoll (Master thesis / Masteroppgave, 2018)
    The nuclide 187Re beta-decays to 187Os with a half-life of approximately 41.6 Gyr. The long half-life and simple relation between 187Re and 187Os makes the ratio a good candidate for a cosmic clock. In order to "use the ...
  • Ranjan, A.; Noterdaeme, P.; Krogager, J.-K.; Petitjean, Patrick; Balashev, S. A.; Bialy, S.; Srianand, R.; Gupta, N.; Fynbo, J. P. U.; Ledoux, C.; Laursen, Peter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We present the detection and detailed analysis of a diffuse molecular cloud at zabs = 2.4636 towards the quasar SDSS J 1513+0352 (zem ≃ 2.68) observed with the X-shooter spectrograph at the Very Large Telescope. We measured ...
  • Wehus, Ingunn Kathrine; Fuskeland, Unni; Eriksen, Hans Kristian Kamfjord; Banday, Anthony J.; Dickinson, Clare F.; Ghosh, Tuhin Subhra; Górski, Krzysztof M.; Lawrence, Cecil R.; Leahy, J. Patrick; Maino, Davide Biagi; Reich, Patricia; Reich, Wolfgang (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We describe a simple but efficient method for deriving a consistent set of monopole and dipole corrections for multi-frequency sky map data sets, allowing robust parametric component separation with the same data set. The ...
  • Gafeira, Ricardo; Lagg, A.; Solanki, S. K.; Jafarzadeh, Shahin; van Noort, M.; Barthol, P.; Blanco Rodriguez, J.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon, L; Hirzberger, J.; Knölker, M.; Orozco Suarez, D.; Riethmüller, T. L.; Schmidt, W. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We use seeing-free high spatial resolution Ca ii H data obtained by the Sunrise observatory to determine properties of slender fibrils in the lower solar chromosphere. In this work we use intensity images taken with the ...
  • Cheung, Mark C. M.; De Pontieu, Bart Walter; Martinez-Sykora, Juan; Testa, Paola; Winebarger, Amy R.; Daw, Adrian N.; Hansteen, Viggo; Antolin, Patrick; Tarbell, Theodore D.; Wüelser, Jean Pierre; Young, Peter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    The signal measured by an astronomical spectrometer may be due to radiation from a multi-component mixture of plasmas with a range of physical properties (e.g., temperature, Doppler velocity). Confusion between multiple ...