Browsing Institutt for teoretisk astrofysikk by Title

Now showing items 254-273 of 683

  • IAU’s Interaction with Young Astronomers 
    Engvold, Oddbjørn (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2018)
    The IAU promotes astronomy as a tool to strengthen science education of young people in developing regions through its International Schools for Young Astronomers (ISYA) and a Teaching for Astronomy Development (TAD) ...
  • Identification of coronal heating events in 3D simulations 
    Kanella, Charalambos; Gudiksen, Boris Vilhelm (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Context. The solar coronal heating problem has been an open question in the science community since 1939. One of the proposed models for the transport and release of mechanical energy generated in the sub-photospheric ...
  • Illuminating gas inflows/outflows in the MUSE deepest fields: Lyα nebulae around forming galaxies at z ≃ 3.3 
    Vanzella, E.; Balestra, I.; Gronke, Max Balthasar; Karman, W.; Caminha, G. B.; Dijkstra, Mark; Rosati, P.; De Barros, S.; Caputi, K.; Grillo, C.; Tozzi, P.; Meneghetti, M.; Mercurio, A.; Gilli, R. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We report the identification of extended Lyα nebulae at z ≃ 3.3 in the Hubble Ultra Deep Field (HUDF, ≃40 kpc × 80 kpc) and behind the Hubble Frontier Field galaxy cluster MACSJ0416 (≃40 kpc), spatially associated with ...
  • Imaging the Solar Chromosphere with the Atacama Large Millimeter/submillimeter Array 
    Parmer, Asbjørn Lie (Master thesis / Masteroppgave, 2014)
    The chromosphere is nearly translucent in the optical and infrared continuum, making it an elusive observational target. In this thesis, I use a CO5BOLD computational 3D radiation magnetohydrodynamics (MHD) model of the ...
  • Impact of magnetic fields on the structure of convective atmospheres of red giant stars 
    Klevas, J.; Kučinskas, A.; Wedemeyer, Sven; Ludwig, H.-G. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We use 3D magnetohydrodynamic CO5BOLD model atmospheres to study the interplay between magnetic fields and convection in the atmospheres of red giant stars. We find that vortex-like structures occur prominently in stars ...
  • Impact of Type II Spicules in the Corona: Simulations and Synthetic Observables 
    Martinez-Sykora, Juan; De Moortel, Ineke; De Pontieu, Bart Walter; Hansteen, Viggo; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    The role of type II spicules in the corona has been a much debated topic in recent years. This paper aims to shed light on the impact of type II spicules in the corona using novel 2.5D radiative MHD simulations, including ...
  • Implications for coronal heating and magnetic field topology from coronal rain observations 
    Antolin, Patrick (Doctoral thesis / Doktoravhandling, 2012)
  • An Improved Model of Wouthuysen-Field Coupling around Galaxies 
    Toresen, Mikael (Master thesis / Masteroppgave, 2015)
    In this thesis we have implemented a basic radiative transfer code to model the radial Lyα scattering rate around the epoch when the first stars and galaxies start forming, and ionizing their surroundings. The model, builds ...
  • Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR 
    Mertens, Florent G.; Mevius, M.; Koopmans, Leon V. E.; Offringa, A. R.; Mellema, Garrelt; Zaroubi, Saleem; Brentjens, M. A.; Gan, H.; Gehlot, Bharat Kumar; Pandey, V. N.; Sardarabadi, A. M.; Vedantham, Harish K.; Yatawatta, Sarod; Asad, Khan M. B.; Ciardi, B.; Chapman, Emma; Gazagnes, S.; Ghara, R.; Ghosh, Abhik; Giri, Sambit Kumar; Iliev, Ilian T.; Jelić, Vibor; Kooistra, Robin; Mondal, Rajesh; Schaye, Joop; Silva, Marta Bruno (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    A new upper limit on the 21 cm signal power spectrum at a redshift of z ≈ 9.1 is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally ...
  • Improving the Planck sky maps through Bayesian component separation 
    Svalheim, Trygve Leithe (Master thesis / Masteroppgave, 2018)
    The Planck satellite has provided a multitude of data images of the full microwave sky, or sky maps, since it saw first light in 2009. Its observations of the Cosmic Microwave Background (CMB) data has been paramount in ...
  • An In-depth Study of the On-disc Counterpart to Type II Spicules 
    Sekse, Dan Henrik (Doctoral thesis / Doktoravhandling, 2013)
  • Indication of the Hanle Effect by Comparing the Scattering Polarization Observed by CLASP in the Lyα and Si III 120.65 nm Lines 
    Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, Han; Kubo, M.; Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa, Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Stepan, Jiri; Belluzzi, L.; Asensio Ramos, A.; Manso Sainz, R.; De Pontieu, Bart Walter; Ichimoto, K.; Carlsson, Mats; Casini, R. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding rocket experiment that has provided the first successful measurement of the linear polarization produced by scattering processes in the hydrogen Lyα line ...
  • Indications for transit-timing variations in the exo-Neptune HAT-P-26b 
    von Essen, Carolina; Wedemeyer, Sven; Sosa, M. S.; Hjorth, M.; Parkash, V.; Freudenthal, J.; Mallonn, M.; Miculán, R. G.; Zibecchi, L.; Cellone, S.; Torres, A. F. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Upon its discovery, the low-density transiting Neptune HAT-P-26b showed a 2.1σ detection drift in its spectroscopic data, while photometric data showed a weak curvature in the timing residuals, the confirmation of which ...
  • Infalling gas in a Lyman-α blob 
    Ao, Yiping; Zheng, Zheng; Henkel, Christian; Nie, Shiyu; Alexandre, Beelen; Cen, Renyue; Dijkstra, Mark; Francis, Paul J.; Geach, James E.; Kohno, Kotaro; Lehnert, Matthew D.; Menten, Karl M.; Wang, Junzhi; Weiss, Axel (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    Lyman-α blobs (LABs) are spatially extended nebulae of emission in the Lyman-α (Lyα) line of hydrogen, seen at high redshifts and most commonly found in the dense environment of star-forming galaxies. A recent study showed ...
  • Instrument Calibration of the Interface Region Imaging Spectrograph (IRIS) Mission 
    Wulser, J. P.; Jaeggli, S.; De Pontieu, Bart Walter; Tarbell, T; Boerner, P.; Freeland, S.; Liu, W.; Timmons, R.; Brannon, S; Kankelborg, C.; Madsen, C; McKillop, S.; Prchlik, J; Saar, S.; Schanche, N; Testa, P; Bryans, P.; Wiesmann, Martin (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    The Interface Region Imaging Spectrograph (IRIS) is a NASA small explorer mission that provides high-resolution spectra and images of the Sun in the 133 – 141 nm and 278 – 283 nm wavelength bands. The IRIS data are archived ...
  • Intensity Contrast as a Function of Underlying Magnetic Field Through the Solar Atmosphere 
    Kjelseth, Ingrid Marie Endresen (Master thesis / Masteroppgave, 2020)
  • An interface region imaging spectrograph first view on solar spicules 
    Pereira, Tiago Mendes Domingos; De Pontieu, Bart Walter; Carlsson, Mats; Hansteen, Viggo; Tarbell, T.D.; Lemen, J.; Title, A.; Boerner, P.; Hurlburt, N.; Wulser, J. P.; Martinez-Sykora, Juan; Kleint, L.; Golub, L.; McKillop, S.; Reeves, K. K.; Saar, S.; Testa, Paola; Tian, H; Jaeggli, S.; Kankelborg, C. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)
    Solar spicules have eluded modelers and observers for decades. Since the discovery of the more energetic type II, spicules have become a heated topic but their contribution to the energy balance of the low solar atmosphere ...
  • Intermittent Reconnection and Plasmoids in UV Bursts in the Low Solar Atmosphere 
    Rouppe van der Voort, Luc; De Pontieu, Bart Walter; Scharmer, G. B.; de la Cruz Rodriguez, Jaime; Martinez-Sykora, Juan; Nobrega-Siverio, Daniel; Guo, L. J.; Jafarzadeh, Shahin; Mendes Domingos Pereira, Tiago; Hansteen, Viggo; Carlsson, Mats; Vissers, Gregal Joan Maria (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Magnetic reconnection is thought to drive a wide variety of dynamic phenomena in the solar atmosphere. Yet, the detailed physical mechanisms driving reconnection are difficult to discern in the remote sensing observations ...
  • Internetwork Chromospheric Bright Grains Observed with IRIS and SST 
    Martinez-Sykora, Juan; Rouppe, Van Der Voort Luc; Carlsson, Mats; De Pontieu, Bart Walter; Mendes Domingos Pereira, Tiago; Boerner, P.; Hurlburt, N.; Kleint, Lucia; Lemen, J.; Tarbell, Ted D.; Title, A.; Wüelser, Jean Pierre; Hansteen, Viggo; Golub, Leon; McKillop, S.; Reeves, K. K.; Saar, S.; Testa, Paola; Tian, Hui; Jaeggli, S.; Kankelborg, C. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    The Interface Region Imaging Spectrograph (IRIS) reveals small-scale rapid brightenings in the form of bright grains all over coronal holes and the quiet Sun. These bright grains are seen with the IRIS 1330, 1400, and 2796 ...
  • The interstellar object ’Oumuamua as a fractal dust aggregate 
    Flekkøy, Eirik Grude; Luu, Jane; Toussaint, Renaud (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    The first known interstellar object 'Oumuamua exhibited a nongravitational acceleration that appeared inconsistent with cometary outgassing, leaving radiation pressure as the most likely force. Barring the alien lightsail ...