Now showing items 316-335 of 600

  • Rudjord, Øystein (Doctoral thesis / Doktoravhandling, 2010)
  • Llinares, Claudio; Hagala, Robert; Mota, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    The quintessence model is one of the simplest and better known alternatives to Einstein’s theory for gravity. The properties of the solutions have been studied in great detail in the background, linear and non-linear ...
  • hong, Jie; Ding, M. D.; Li, Ying; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    The Fe i 6173 Å line is widely used in the measurements of vector magnetic fields by instruments including the Helioseismic and Magnetic Imager (HMI). We perform non-local thermodynamic equilibrium calculations of this ...
  • Lind, K.; Amarsi, A. M.; Asplund, M.; Barklem, P. S.; Bautista, M.; Bergemann, M.; Collet, R.; Kiselman, D.; Leenaarts, Jorrit; Mendes Domingos Pereira, Tiago (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Our ability to model the shapes and strengths of iron lines in the solar spectrum is a critical test of the accuracy of the solar iron abundance, which sets the absolute zero-point of all stellar metallicities. We use an ...
  • Tayfeh, Bagheri F. (Master thesis / Masteroppgave, 2013)
    The existence of dark energy in the universe is hypothesized to explain the accelerated expansion of today’s universe and the inflationary expansion of very early universe; accelerated expansion of today’s universe is ...
  • Bakke, Helle; Frogner, Lars; Gudiksen, Boris Vilhelm (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    Context: We introduce a model for including accelerated particles in pure magnetohydrodynamics (MHD) simulations of the solar atmosphere. Aims: We show that the method is viable and produces results that enhance the realism ...
  • Nóbrega Siverio, Daniel Elias; Moreno-Insertis, Fernando; Martinez-Sykora, Juan; Carlsson, Mats; Szydlarski, Mikolaj Marcin (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Context. Magnetic flux emergence from the solar interior has been shown to be a key mechanism for unleashing a wide variety of phenomena. However, there are still open questions concerning the rise of the magnetized plasma ...
  • Olluri, Kosovare (Doctoral thesis / Doktoravhandling, 2014)
    De siste par tiårene har avanserte forskningssatellitter og rombaserte observatorier gitt oss innsikt i en svært dynamisk solatmosfære, hvor lokale variable som temperatur og tetthet endres på korte tidsskalaer. Disse ...
  • Yang, Weiqiang; Pan, Supriya; Mota, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    © 2017 American Physical Society
  • Riemer-Sørensen, Signe; Jenssen, Espen Sem (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
  • Von Marttens, Rodrigo F.; Marra, Valerio; Casarini, Luciano; Gonzalez, J. E.; Alcaniz, Jailson S (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Since there is no known symmetry in nature that prevents a nonminimal coupling between the dark energy (DE) and cold dark matter (CDM) components, such a possibility constitutes an alternative to standard cosmology, with ...
  • Frogner, Lars (Master thesis / Masteroppgave, 2018)
    Solar flares play a key role in the dynamics of the solar atmosphere. They occur with a wide range of energies, from the largest X-class flares representing some of the most violent releases of energy in the solar system, ...
  • Bjørgen, Johan Pires (Master thesis / Masteroppgave, 2014)
    Solving the non-LTE radiative transfer problem in stellar atmospheres is computationally demanding. There is therefore an interest to investigate new methods to solve this problem effectively. A numerical method, multigrid, ...
  • Hansteen, Viggo; Guerreiro, Nuno Miguel Rodrigues; De Pontieu, Bart Walter; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    Advanced three-dimensional (3D) radiative MHD simulations now reproduce many properties of the outer solar atmosphere. When including a domain from the convection zone into the corona, a hot chromosphere and corona are ...
  • Guerreiro, Nuno Miguel Rodrigues; Carlsson, Mats; Hansteen, Viggo (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2013)
    Observations in the Hα line of hydrogen and the H and K lines of singly ionized calcium on the solar limb reveal the existence of structures with jet-like behavior, usually designated as spicules. The driving mechanism for ...
  • Rekaa, Vegard Lundby; Pecseli, Hans; Trulsen, Jan Karsten (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)
    With reference to laboratory Q-machine studies we analyze the dynamics of a plasma diode under external forcing. Assuming a strong axial magnetic field, the problem is analyzed in one spatial dimension by a particle-in-cell ...
  • Karlsen, Karl Niklas (Master thesis / Hovedoppgave, 2003)
    The thesis examines the relation between the magnetic field as measured by MDI and the continuum intensity at four different wavelengths (1319, 1199, 1037 and 910Å) as measured by SUMER. A method for copointing the instruments ...
  • Bergemann, Maria; Gallagher, Andrew J.; Eitner, Philipp; Bautista, Manuel; Collet, Remo; Yakovleva, Svetlana A.; Mayriedl, Anja; Plez, Bertrand; Carlsson, Mats; Leenaarts, Jorrit; Belyaev, Andrey K.; Hansen, Camilla (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Manganese (Mn) is a key Fe-group element, commonly employed in stellar population and nucleosynthesis studies to explore the role of SN Ia. We have developed a new non-local thermodynamic equilibrium (NLTE) model of Mn, ...
  • De Pontieu, Bart Walter; De Moortel, I.; Martinez-Sykora, Juan; McIntosh, S. W. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Spicules have been proposed as significant contributors to the mass and energy balance of the corona. While previous observations have provided a glimpse of short-lived transient brightenings in the corona that are associated ...
  • Schmit, D.; Bryans, P.; De Pontieu, Bart Walter; McIntosh, Scott; Leenaarts, Jorrit; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    The Mg ii h&k doublet are two of the primary spectral lines observed by the Sun-pointing Interface Region Imaging Spectrograph (IRIS). These lines are tracers of the magnetic and thermal environment that spans from the ...