Browsing Institutt for teoretisk astrofysikk by Author "Hansteen, Viggo Haraldson"

Now showing items 1-17 of 17

  • A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS) 
    De Pontieu, Bart Walter; Polito, Vanessa; Hansteen, Viggo Haraldson; Testa, Paola; Reeves, Katharine K.; Antolin, Patrick; Nóbrega Siverio, Daniel Elias; Kowalski, Adam F.; Martinez-Sykora, Juan; Carlsson, Mats; McIntosh, Scott W.; Liu, Wei; Daw, Adrian N.; Kankelborg, Charles C. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    Abstract The Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images and spectra of the solar atmosphere since July 2013. IRIS is the highest resolution observatory to provide ...
  • A Novel Inversion Method to Determine the Coronal Magnetic Field Including the Impact of Bound–Free Absorption 
    Martinez-Sykora, Juan; Hansteen, Viggo Haraldson; De Pontieu, Bart Walter; Landi, Enrico (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    The magnetic field governs the corona; hence, it is a crucial parameter to measure. Unfortunately, existing techniques for estimating its strength are limited by strong assumptions and limitations. These techniques include ...
  • Chromospheric and coronal heating in an active region plage by dissipation of currents from braiding 
    Bose, Souvik; De Pontieu, Bart Walter; Hansteen, Viggo Haraldson; Sainz Dalda, Alberto; Savage, Sabrina; Winebarger, Amy (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
    Abstract The question of what heats the outer solar atmosphere remains one of the longstanding mysteries in astrophysics. Statistical studies of Sun-like stars reveal a correlation between global chromospheric and coronal ...
  • Chromospheric Heating from Local Magnetic Growth and Ambipolar Diffusion under Nonequilibrium Conditions 
    Martinez-Sykora, Juan; de la Cruz Rodriguez, Jaime; Gošić, Milan; Sainz Dalda, Alberto; Hansteen, Viggo Haraldson; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract The heating of the chromosphere in internetwork regions remains one of the foremost open questions in solar physics. In the present study, we tackle this old problem by using a very-high-spatial-resolution ...
  • Comparative clustering analysis of Ca II 854.2 nm spectral profiles from simulations and observations 
    Moe, Thore Espedal; Pereira, Tiago; Rouppe van der Voort, Luc; Carlsson, Mats; Hansteen, Viggo Haraldson; Calvo, Flavio; Leenaarts, Jorrit (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
    Context. Synthetic spectra from 3D models of the solar atmosphere have become increasingly successful at reproducing observations, but there are still some outstanding discrepancies for chromospheric spectral lines, such ...
  • Detailed Description of the Collision Frequency in the Solar Atmosphere 
    Wargnier, Q.M.; Martinez-Sykora, Juan; Hansteen, Viggo Haraldson; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    This work aims to provide an accurate description and calculations of collision frequencies in conditions relevant to the solar atmosphere. To do so, we focus on the detailed description of the collision frequency in the ...
  • Line formation of He I D3 and He I 10 830 Å in a small-scale reconnection event 
    Libbrecht, Tine; Bjørgen, Johan Pires; Leenaarts, Jorrit; de la Cruz Rodríguez, Jaime; Hansteen, Viggo Haraldson; Joshi, Jayant (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    Context. Ellerman bombs (EBs) and UV bursts are small-scale reconnection events that occur in the region of the upper photosphere to the chromosphere. It has recently been discovered that these events can have emission ...
  • Linking the Sun to the Heliosphere Using Composition Data and Modelling: A Test Case with a Coronal Jet 
    Parenti, Susanna; Chifu, Iulia; Del Zanna, Giulio; Edmondson, Justin; Giunta, Alessandra; Hansteen, Viggo Haraldson; Higginson, Aleida; Laming, J. Martin; Lepri, Susan T.; Lynch, Benjamin J.; Rivera, Yeimy J.; von Steiger, Rudolf; Wiegelmann, Thomas; Wimmer-Schweingruber, Robert F.; Zambrana Prado, Natalia; Pelouze, Gabriel (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
    Our understanding of the formation and evolution of the corona and the heliosphere is linked to our capability of properly interpret the data from remote sensing and in-situ observations. In this respect, being able to ...
  • Multifluid Simulations of Upper-chromospheric Magnetic Reconnection with Helium-Hydrogen Mixture 
    Wargnier, Q.M.; Martinez-Sykora, Juan; Hansteen, Viggo Haraldson; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract Our understanding of magnetic reconnection (MR) under chromospheric conditions remains limited. Recent observations have demonstrated the important role of ion–neutral interactions in the dynamics of the ...
  • Numerical Simulations and Observations of Mg II in the Solar Chromosphere 
    Hansteen, Viggo Haraldson; Martinez-Sykora, Juan; Carlsson, Mats; De Pontieu, Bart Walter; Gošić, Milan; Bose, Souvik (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    The Mg ii h and k lines are among the best diagnostic tools of the upper solar chromosphere. This region of the atmosphere is of particular interest, as it is the lowest region of the Sun's atmosphere where the magnetic ...
  • Probing the Physics of the Solar Atmosphere with the Multi-slit Solar Explorer (MUSE). I. Coronal Heating 
    De Pontieu, Bart Walter; Testa, Paola; Martinez-Sykora, Juan; Antolin, Patrick; Karampelas, Konstantinos; Hansteen, Viggo Haraldson; Rempel, Matthias; Cheung, Mark C. M.; Reale, Fabio; Danilovic, Sanja; Pagano, Paolo; Polito, Vanessa; de Moortel, Ineke; Nóbrega Siverio, Daniel Elias; Van Doorsselaere, Tom; Petralia, Antonino; Asgari-Targhi, Mahboubeh; Boerner, Paul; Carlsson, Mats; Chintzoglou, Georgios; Daw, Adrian; DeLuca, Edward; Golub, Leon; Matsumoto, Takuma; Ugarte-Urra, Ignacio; McIntosh, Scott W. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
  • Probing the Physics of the Solar Atmosphere with the Multi-slit Solar Explorer (MUSE). II. Flares and Eruptions 
    Cheung, Mark C. M.; Martinez-Sykora, Juan; Testa, Paola; De Pontieu, Bart Walter; Chintzoglou, Georgios; Rempel, Matthias; Polito, Vanessa; Kerr, Graham S.; Reeves, Katharine K.; Fletcher, Lyndsay; Jin, Meng; Nóbrega Siverio, Daniel Elias; Danilovic, Sanja; Antolin, Patrick; Allred, Joel; Hansteen, Viggo Haraldson; Ugarte-Urra, Ignacio; DeLuca, Edward; Longcope, Dana; Takasao, Shinsuke; DeRosa, Marc L.; Boerner, Paul; Jaeggli, Sarah; Nitta, Nariaki V.; Daw, Adrian; Carlsson, Mats; Golub, Leon (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Current state-of-the-art spectrographs cannot resolve the fundamental spatial (subarcseconds) and temporal (less than a few tens of seconds) scales of the coronal dynamics of solar flares and eruptive phenomena. The ...
  • Solar Orbiter and SDO Observations, and a Bifrost Magnetohydrodynamic Simulation of Small-scale Coronal Jets 
    Panesar, Navdeep K.; Hansteen, Viggo Haraldson; Tiwari, Sanjiv K.; Cheung, Mark C. M.; Berghmans, David; Müller, Daniel (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract We report high-resolution, high-cadence observations of five small-scale coronal jets in an on-disk quiet Sun region observed with Solar Orbiter’s EUI/HRI EUV in 174 Å. We combine the HRI EUV images with ...
  • SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation 
    Tiwari, Sanjiv K.; Hansteen, Viggo Haraldson; De Pontieu, Bart Walter; Panesar, Navdeep K.; Berghmans, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    We report on the presence of numerous tiny bright dots in and around an emerging flux region (an X-ray/coronal bright point) observed with SolO's EUI/HRIEUV in 174 Å. These dots are roundish and have a diameter of 675 ± ...
  • Stirring the base of the solar wind: On heat transfer and vortex formation 
    Finley, Adam J.; Brun, Allan Sacha; Carlsson, Mats; Hansteen, Viggo Haraldson; Shoda, M. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Context. Current models of the solar wind must approximate (or ignore) the small-scale dynamics within the solar atmosphere; however, these are likely important in shaping the emerging wave-turbulence spectrum that ultimately ...
  • The European Solar Telescope 
    Quintero Noda, Carlos; Schlichenmaier, R.; Bellot Rubio, L.R.; Löfdahl, M.G.; Khomenko, E.; Jurčák, J.; Leenaarts, Jorrit; Kuckein, C.; González Manrique, S.J.; Gunár, S.; Nelson, C.J.; de la Cruz Rodríguez, Jaime; Tziotziou, K.; Tsiropoula, G.; Aulanier, Guillaume; Aboudarham, J.; Allegri, D.; Alsina Ballester, E.; Amans, J.P.; Asensio Ramos, A.; Bailén, F.J.; Balaguer, M.; Baldini, V.; Balthasar, H.; Barata, T.; Barczynski, K.; Barreto Cabrera, M.; Baur, A.; Béchet, C.; Beck, C.; Belío-Asín, M.; Bello-González, N.; Belluzzi, L.; Bentley, R.D.; Berdyugina, S.V.; Berghmans, D.; Berlicki, A.; Berrilli, F.; Berkefeld, T.; Bettonvil, F.; Bianda, M.; Bienes Pérez, J.; Bonaque-González, S.; Brajša, R.; Bommier, V.; Bourdin, P.-A.; Burgos Martín, J.; Calchetti, D.; Calcines, A.; Calvo Tovar, J.; Campbell, R.J.; Carballo-Martín, Y.; Carbone, V.; Carlin, E.S.; Carlsson, Mats; Castro López, J.; Cavaller, L.; Cavallini, F.; Cauzzi, G.; Cecconi, M.; Chulani, H.M.; Cirami, R.; Consolini, G.; Coretti, I.; Cosentino, R.; Cózar-Castellano, J.; Dalmasse, K.; Danilovic, S.; De Juan Ovelar, M.; Del Moro, D.; del Pino Alemán, T.; del Toro Iniesta, J.C.; Denker, C.; Dhara, S.K.; Di Marcantonio, P.; Díaz Baso, C.J.; Diercke, A.; Dineva, E.; Díaz-García, J.J.; Doerr, H.-P.; Doyle, G.; Erdelyi, R.; Ermolli, I.; Escobar Rodríguez, A.; Esteban Pozuelo, S.; Faurobert, M.; Felipe, T.; Feller, A.; Feijoo Amoedo, N.; Femenía Castellá, B.; Fernandes, J.; Ferro Rodríguez, I.; Figueroa, I.; Fletcher, Lyndsay; Franco Ordovas, A.; Gafeira, R.; Gardenghi, R.; Gelly, B.; Giorgi, F.; Gisler, D.; Giovannelli, L.; González, F.; González, J.B.; González-Cava, J.M.; González García, M.; Gömöry, P.; Gracia, F.; Grauf, B.; Greco, V.; Grivel, C.; Guerreiro, N.; Guglielmino, S.L.; Hammerschlag, R.; Hanslmeier, A.; Hansteen, Viggo Haraldson; Heinzel, P.; Hernández-Delgado, A.; Hernández Suárez, E.; Hidalgo, S.L.; Hill, F.; Hizberger, J.; Hofmeister, S.; Jägers, A.; Janett, G.; Jarolim, R.; Jess, D.; Jiménez Mejías, D.; Jolissaint, L.; Kamlah, R.; Kapitán, J.; Kašparová, J.; Keller, C.U.; Kentischer, T.; Kiselman, D.; Kleint, Lucia; Klvana, M.; Kontogiannis, I.; Krishnappa, N.; Kučera, A.; Labrosse, N.; Lagg, A.; Landi Degl'Innocenti, E.; Langlois, M.; Lafon, M.; Laforgue, D.; Le Men, C.; Lepori, B.; Lepreti, F.; Lindberg, B.; Lilje, Per Barth; López Ariste, A.; López Fernández, V.A.; López Jiménez, A.C.; López López, R.; Manso Sainz, R.; Marassi, A.; Marco de la Rosa, J.; Marino, J.; Marrero, J.; Martín, A.; Martín Gálvez, A.; Martín Hernando, Y.; Masciadri, E.; Martínez González, M.; Matta-Gómez, A.; Mato, A.; Mathioudakis, M.; Matthews, S.; Mein, P.; Merlos García, F.; Moity, J.; Montilla, I.; Molinaro, M.; Molodij, G.; Montoya, L.M.; Munari, M.; Murabito, M.; Núñez Cagigal, M.; Oliviero, M.; Orozco Suárez, D.; Ortiz, Ada; Padilla-Hernández, C.; Paéz Mañá, E.; Paletou, F.; Pancorbo, J.; Pastor Cañedo, A.; Pastor Yabar, A.; Peat, A.W.; Pedichini, F.; Peixinho, N.; Peñate, J.; Pérez de Taoro, A.; Peter, H.; Petrovay, K.; Piazzesi, R.; Pietropaolo, E.; Pleier, O.; Poedts, S.; Pötzi, W.; Podladchikova, T.; Prieto, G.; Quintero Nehrkorn, J.; Ramelli, R.; Ramos Sapena, Y.; Rasilla, J.L.; Reardon, K.; Rebolo, R.; Regalado Olivares, S.; Reyes García-Talavera, M.; Riethmüller, T.L.; Rimmele, T.; Rodríguez Delgado, H.; Rodríguez González, N.; Rodríguez-Losada, J.A.; Rodríguez Ramos, L.F.; Romano, P.; Roth, M.; Rouppe van der Voort, Luc; Rudawy, P.; Ruiz de Galarreta, C.; Rybák, J.; Salvade, A.; Sánchez-Capuchino, J.; Sánchez Rodríguez, M.L.; Sangiorgi, M.; Sayède, F.; Scharmer, G.; Scheiffelen, T.; Schmidt, W.; Schmieder, Birgitte; Scirè, C.; Scuderi, S.; Siegel, B.; Sigwarth, M.; Simões, P.J.A.; Snik, F.; Sliepen, G.; Sobotka, M.; Socas-Navarro, H.; Sola La Serna, P.; Solanki, S.K.; Soler Trujillo, M.; Soltau, D.; Sordini, A.; Sosa Méndez, A.; Stangalini, M.; Steiner, O.; Stenflo, J.O.; Štěpán, J.; Strassmeier, K.G.; Sudar, D.; Suematsu, Y.; Sütterlin, P.; Tallon, M.; Temmer, M.; Tenegi, F.; Tritschler, A.; Trujillo Bueno, J.; Turchi, A.; Utz, D.; van Harten, G.; van Noort, M.; van Werkhoven, T.; Vansintjan, R.; Vaz Cedillo, J.J.; Vega Reyes, N.; Verma, M.; Veronig, A.M.; Viavattene, G.; Vitas, N.; Vögler, A.; von der Lühe, O.; Volkmer, R.; Waldmann, T.A.; Walton, D.; Wisniewska, A.; Zeman, J.; Zeuner, F.; Zhang, L.Q.; Zuccarello, F.; Collados, M. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise ...
  • The Impact of Multifluid Effects in the Solar Chromosphere on the Ponderomotive Force under SE and NEQ Ionization Conditions 
    Martinez-Sykora, Juan; De Pontieu, Bart Walter; Hansteen, Viggo Haraldson; Testa, Paola; Wargnier, Q.M.; Szydlarski, Mikolaj (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract The ponderomotive force has been suggested to be the main mechanism to produce the so-called first ionization potential (FIP) effect—the enrichment of low-FIP elements observed in the outer solar atmosphere, ...