Browsing Institutt for teoretisk astrofysikk by Title

Now showing items 550-569 of 1278

  • HIGH-RESOLUTION OBSERVATIONS OF THE SHOCK WAVE BEHAVIOR FOR SUNSPOT OSCILLATIONS WITH THE INTERFACE REGION IMAGING SPECTROGRAPH 
    Tian, H; DeLuca, E.; Reeves, K. K.; McKillop, S.; De Pontieu, Bart Walter; Martinez-Sykora, Juan; Carlsson, Mats; Hansteen, Viggo; Kleint, L.; Cheung, M; Golub, L.; Saar, S.; Testa, Paola; Weber, M.; Lemen, J.; Title, A.; Boerner, P.; Hurlburt, N.; Tarbell, T.D.; Wuelser, J. P.; Kankelborg, C.; Jaeggli, S.; McIntosh, S.W. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)
    We present the first results of sunspot oscillations from observations by the Interface Region Imaging Spectrograph. The strongly nonlinear oscillation is identified in both the slit-jaw images and the spectra of several ...
  • High-resolution observations of the solar photosphere, chromosphere, and transition region: A database of coordinated IRIS and SST observations 
    Rouppe van der Voort, Luc; De Pontieu, Bart Walter; Carlsson, Mats; de la Cruz Rodriguez, Jaime; Bose, Souvik; Chintzoglou, Georgios; Drews, Ainar; Froment, Clara; Gošić, Milan; Graham, David R.; Hansteen, Viggo; de Jorge Henriques, Vasco Manuel; Jafarzadeh, Shahin; Joshi, Jayant; Kleint, Lucia; Kohutova, Petra; Leifsen, Torben; Martinez-Sykora, Juan; Nóbrega Siverio, Daniel Elias; Ortiz, Ada; Mendes Domingos Pereira, Tiago; Popovas, Andrius; Quintero Noda, Carlos; Sainz Dalda, Alberto; Scharmer, Göran B.; Schmit, Donald; Scullion, Eamon; Skogsrud, Håkon; Szydlarski, Mikolaj Marcin; Timmons, R.; Vissers, Gregal Joan Maria; Woods, M. M.; Zacharias, Pia (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    NASA’s Interface Region Imaging Spectrograph (IRIS) provides high-resolution observations of the solar atmosphere through ultraviolet spectroscopy and imaging. Since the launch of IRIS in June 2013, we have conducted ...
  • High-resolution spectropolarimetric observations of the temporal evolution of magnetic fields in photospheric bright points 
    Keys, Peter H.; Reid, Aaron L.; Mathioudakis, Mihalis; Shelyag, Sergey I.; de Jorge Henriques, Vasco Manuel; Hewitt, Rebecca L.; del Moro, Dario; Jafarzadeh, Shahin; Jess, David B.; Stangalini, Marco (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    Context. Magnetic bright points (MBPs) are dynamic, small-scale magnetic elements often found with field strengths of the order of a kilogauss within intergranular lanes in the photosphere. Aims. Here we study the evolution ...
  • High-resolution wave dynamics in the lower solar atmosphere 
    Jess, David B.; Keys, Peter H.; Stangalini, Marco; Jafarzadeh, Shahin (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
    The magnetic and convective nature of the Sun's photosphere provides a unique platform from which generated waves can be modelled, observed, and interpreted across a wide breadth of spatial and temporal scales. As oscillations ...
  • Hinode/EIS spectroscopy and modeling 
    Skogvoll, Marte Elisabeth (Master thesis / Masteroppgave, 2007)
  • Homologous helical jets: Observations by IRIS, SDO, and Hinode and magnetic modeling with data-driven simulations 
    Cheung, Mark C. M.; De Pontieu, Bart Walter; Tarbell, Theodore D.; Fu, Y.; Tian, H.; Testa, Paola; Reeves, K. K.; Martinez-Sykora, Juan; Boerner, P.; Wulser, J. P.; Lemen, J.; Title, Alan M.; Hurlburt, N.; Kleint, L.; Kankelborg, C.; Jaeggli, S.; Golub, L.; McKillop, S.; Saar, S.; Carlsson, Mats; Hansteen, Viggo (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    We report on observations of recurrent jets by instruments on board the Interface Region Imaging Spectrograph, Solar Dynamics Observatory (SDO), and Hinode spacecraft. Over a 4 hr period on 2013 July 21, recurrent coronal ...
  • A Hot Downflowing Model Atmosphere for Umbral Flashes and the Physical Properties of Their Dark Fibrils 
    de Jorge Henriques, Vasco Manuel; Mathioudakis, M.; Socas-Navarro, H.; de la Cruz Rodriguez, Jaime (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We perform non-LTE inversions in a large set of umbral flashes, including the dark fibrils visible within them, and in the quiescent umbra by using the inversion code NICOLE on a set of full Stokes high-resolution Ca ii ...
  • Hot X-ray onsets of solar flares 
    Hudson, Hugh S.; Simões, Paulo J. A.; Fletcher, Lyndsay; Hayes, Laura A.; Hannah, Iain G. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    ABSTRACT The study of the localized plasma conditions before the impulsive phase of a solar flare can help us understand the physical processes that occur leading up to the main flare energy release. Here, we ...
  • Hubble Constant Measurement from Three Large-separation Quasars Strongly Lensed by Galaxy Clusters 
    Napier, Kate; Sharon, Keren; Dahle, Håkon; Bayliss, Matthew; Gladders, Michael D.; Mahler, Guillaume; Rigby, Jane R.; Florian, Michael (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Tension between cosmic microwave background–based and distance ladder–based determinations of the Hubble constant H0 motivates the pursuit of independent methods that are not subject to the same systematic effects. A ...
  • Hubble Space Telescope Wide Field Camera 3 Observations of Escaping Lyman Continuum Radiation from Galaxies and Weak AGN at Redshifts z ~ 2.3–4.1 
    Smith, Brent M.; Windhorst, Rogier A.; Jansen, Rolf A.; Cohen, Seth H.; Jiang, Linhua; Dijkstra, Mark; Koekemoer, Anton M.; Bielby, Richard; Inoue, Akio K.; MacKenty, John W.; O'Connell, Robert W.; Silk, Joseph I. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We present observations of escaping Lyman Continuum (LyC) radiation from 34 massive star-forming galaxies (SFGs) and 12 weak AGN with reliably measured spectroscopic redshifts at $z\simeq 2.3\mbox{--}4.1$. We analyzed ...
  • Hybrid Pℓ(k): general, unified, non-linear matter power spectrum in redshift space 
    Bose, Benjamin; Winther, Hans Arnold; Pourtsidou, Alkistis; Casas, Santiago; Lombriser, Lucas; Xia, Qianli; Cataneo, Matteo (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    Constraints on gravity and cosmology will greatly benefit from performing joint clustering and weak lensing analyses on large-scale structure data sets. Utilising non-linear information coming from small physical scales ...
  • Hydrodynamic effects in the symmetron and f(R)-gravity models 
    Hammami, Amir; Llinares, Claudio; Mota, David; Winther, Hans Arnold (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    In this paper, we present the first results from implementing two scalar–tensor modified gravity theories, the symmetron and the Hu–Sawicki f(R)-gravity model, into a hydrodynamic N-body code with dark matter particles and ...
  • Hydrogen Balmer Line Broadening in Solar and Stellar Flares 
    Kowalski, Adam F.; Allred, Joel C.; Uitenbroek, Han; Tremblay, Pier-Emmanuel; Brown, Stephen; Carlsson, Mats; Osten, R. A.; Wisniewski, John P.; Hawley, Suzanne L. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    The broadening of the hydrogen lines during flares is thought to result from increased charge (electron, proton) density in the flare chromosphere. However, disagreements between theory and modeling prescriptions have ...
  • Hydrogen ionization in 3d solar atmosphere models 
    Golding, Thomas Peter (Master thesis / Masteroppgave, 2010)
    The solar chromosphere is a region where the thermodynamics are out of equilibrium, and realistic values of temperature and electron densities here are difficult to obtain. Hydrogen, being the most abundant element in solar ...
  • Hydrogen ionization in the solar atmosphere : exact and simplified treatments 
    Sollum, Espen (Master thesis / Hovedoppgave, 1999)
  • Hydrogen recombination continuum as the radiative model for stellar optical flares 
    Simões, Paulo J.A.; Araújo, Alexandre; Válio, Adriana; Fletcher, Lyndsay (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
    ABSTRACT The study of stellar flares has increased with new observations from CoRoT, Kepler, and TESS satellites, revealing the broad-band visible emission from these events. Typically, stellar flares have been ...
  • Hyperspectral detection of spicules in Ca II K 
    Sand, Mats Ola (Master thesis / Masteroppgave, 2021)
    Solar spicules are chromospheric jets of up-flowing plasma observed all over the Sun, and can be categorized into type i and type ii spicules. Type ii spicules are more dynamic and more ubiquitous, yet their origin and ...
  • Hα and Hβ Emission in a C3.3 Solar Flare: Comparison between Observations and Simulations 
    Capparelli, Vincenzo; Zuccarello, Francesca; Romano, Paolo; Simões, Paulo J. A.; Fletcher, Lyndsay; Kuridze, D.; Mathioudakis, M.; Keys, Peter H.; Cauzzi, Gianna; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
  • Hα Line Profile Asymmetries and the Chromospheric Flare Velocity Field 
    Kuridze, D.; Mathioudakis, M.; Simoes, P. J. A.; Rouppe, Van Der Voort Luc; Carlsson, Mats; Jafarzadeh, Shahin; Allred, J. C.; Kowalski, Adam F.; Kennedy, M; Fletcher, L.; Graham, D.; Keenan, F. P. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    The asymmetries observed in the line profiles of solar flares can provide important diagnostics of the properties and dynamics of the flaring atmosphere. In this paper the evolution of the Hα and Ca ii λ8542 lines are ...
  • 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) ...