Browsing Institutt for teoretisk astrofysikk by Author "Jafarzadeh, Shahin"

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  • A novel approach to identify resonant MHD wave modes in solar pores and sunspot umbrae: B − ω analysis 
    Stangalini, Marco; Jess, David B.; Verth, Gary; Fedun, Viktor; Fleck, Bernhard; Jafarzadeh, Shahin; Keys, Peter H.; Murabito, Mariarita; Calchetti, Daniele; Aldhafeeri, Anwar A.; Berrilli, Francesco; Del Moro, Dario; Jefferies, Stuart M.; Terradas, J.; Soler, Roberto (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    The umbral regions of sunspots and pores in the solar photosphere are generally dominated by 3 mHz oscillations, which are due to p -modes penetrating the magnetic region. In these locations, wave power is also significantly ...
  • An overall view of temperature oscillations in the solar chromosphere with ALMA 
    Jafarzadeh, Shahin; Wedemeyer, Sven; Fleck, Bernhard; Stangalini, M.; Jess, D. B.; Morton, R. J.; Szydlarski, Mikolaj Marcin; de Jorge Henriques, Vasco Manuel; Zhu, X.; Wiegelmann, T.; Guevara Gomez, Juan Camilo; Grant, Samuel D. T.; Chen, B.; Reardon, K.; White, S. M. (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    By direct measurements of the gas temperature, the Atacama Large Millimeter/submillimeter Array (ALMA) has yielded a new diagnostic tool to study the solar chromosphere. Here, we present an overview of the brightness-temperature ...
  • Analysis of Pseudo-Lyapunov Exponents of Solar Convection Using State-of-the-Art Observations 
    Viavattene, Giorgio; Murabito, M.; Guglielmino, S. L.; Ermolli, I.; Consolini, G.; Giorgi, F.; Jafarzadeh, Shahin (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    The solar photosphere and the outer layer of the Sun’s interior are characterized by convective motions, which display a chaotic and turbulent character. In this work, we evaluated the pseudo-Lyapunov exponents of the ...
  • Characterization of shock wave signatures at millimetre wavelengths from Bifrost simulations 
    Eklund, Henrik; Wedemeyer, Sven; Snow, Ben; Jess, David B.; Jafarzadeh, Shahin; Grant, Samuel D. T.; Carlsson, Mats; Szydlarski, Mikolaj Marcin (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    Observations at millimetre wavelengths provide a valuable tool to study the small-scale dynamics in the solar chromosphere. We evaluate the physical conditions of the atmosphere in the presence of a propagating shock wave ...
  • A chromospheric resonance cavity in a sunspot mapped with seismology 
    Jess, David B.; Snow, Ben; Houston, Scott J.; Bortha, Gert J. J.; Fleck, Bernhard; Prasad, S. Krishna; Asensio Ramos, Andres; Morton, Richard J.; Keys, Peter H.; Jafarzadeh, Shahin; Stangalini, Marco; Grant, Samuel D. T.; Christian, Damian J. (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    Sunspots are intense collections of magnetic fields that pierce through the Sun’s photosphere, with their signatures extending upwards into the outermost extremities of the solar corona1. Cutting-edge observations and ...
  • Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST) 
    Rast, Mark P.; Bello González, Nazaret; Bellot Rubio, Luis R.; Cao, Wenda; Cauzzi, Gianna; DeLuca, Edward; De Pontieu, Bart Walter; Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa, Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler, Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun, Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres, Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.; Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini, Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena; DeForest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor; Fischer, Catherine E.; González Manrique, Sergio Javier; Hahn, Michael; Harra, Louise K.; de Jorge Henriques, Vasco Manuel; Hurlburt, Neal E.; Jaeggli, Sarah A.; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys, Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.; Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis, Mihalis; McAtee, R. T. James; McIntosh, Scott W.; McKenzie, David E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson, Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.; Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.; Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava, Abhishek Kumar; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas, Angelos; Wang, Haimin; Wang, Yi-Ming (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    The National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST) will revolutionize our ability to measure, understand, and model the basic physical processes that control the structure and dynamics of the Sun ...
  • Height Dependence of the Penumbral Fine-scale Structure in the Inner Solar Atmosphere 
    Murabito, M.; Ermolli, I.; Giorgi, F.; Stangalini, M.; Guglielmino, S. L.; Jafarzadeh, Shahin; Socas-Navarro, H.; Romano, P.; Zuccarello, F. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    We studied the physical parameters of the penumbra in a large and fully developed sunspot, one of the largest over the last two solar cycles, by using full-Stokes measurements taken at the photospheric Fe i 617.3 nm and ...
  • High-frequency oscillations in small chromospheric bright features observed with Atacama Large Millimetre/Submillimetre Array 
    Guevara Gomez, Juan Camilo; Jafarzadeh, Shahin; Wedemeyer, Sven; Szydlarski, Mikolaj Marcin; Stangalini, M.; Fleck, Bernhard; Keys, Peter H. (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    We report detection of oscillations in brightness temperature, size and horizontal velocity of three small bright features in the chromosphere of a plage/enhanced-network region. The observations, which were taken with ...
  • High-frequency Oscillations in Small Magnetic Elements Observed with Sunrise/SuFI 
    Jafarzadeh, Shahin; Solanki, S. K.; Stangalini, M.; Steiner, Oskar; Cameron, R. H.; Danilovic, S. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We characterize waves in small magnetic elements and investigate their propagation in the lower solar atmosphere from observations at high spatial and temporal resolution. We use the wavelet transform to analyze oscillations ...
  • High-frequency Waves in Chromospheric Spicules 
    Bate, W.; Jess, D.B.; Nakariakov, V.M.; Grant, S.D.T.; Jafarzadeh, Shahin; Stangalini, M.; Keys, P.H.; Christian, D.J.; Keenan, F.P. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Using high-cadence observations from the Hydrogen-alpha Rapid Dynamics camera imaging system on the Dunn Solar Telescope, we present an investigation of the statistical properties of transverse oscillations in spicules ...
  • 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 ...
  • 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 ...
  • 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 ...
  • Investigating the Effect of Solar Ambient and Data Characteristics on Ca II K Observations and Line Profile Measurements 
    Murabito, M.; Ermolli, I.; Chatzistergos, T.; Jafarzadeh, Shahin; Giorgi, F.; Rouppe van der Voort, Luc (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract We analyzed state-of-the-art observations of the solar atmosphere to investigate the dependence of the Ca ii K brightness of several solar features on spectral bandwidth and spatial resolution of the ...
  • Investigating the origin of magnetic perturbations associated with the FIP Effect 
    Murabito, Mariarita; Stangalini, Marco; Baker, Deborah; Valori, Gherardo; Jess, D.B.; Jafarzadeh, Shahin; Brooks, D.H.; Ermolli, I.; Giorgi, F.; Grant, Samuel D. T.; Long, D.M.; van Driel-Gesztelyi, Lidia (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    Recently, magnetic oscillations were detected in the chromosphere of a large sunspot and found to be linked to the coronal locations where a first ionization potential (FIP) effect was observed. In an attempt to shed light ...
  • Kinematics of Magnetic Bright Features in the Solar Photosphere 
    Jafarzadeh, Shahin; Solanki, S. K.; Cameron, R. H.; Barthol, P.; Blanco Rodriguez, J.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon, L; Hirzberger, J.; Knölker, M.; Martinez Pillet, V.; Orozco Suarez, D.; Riethmüller, T. L.; Schmidt, W.; van Noort, M. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    © 2017. The American Astronomical Society. All rights reserved.
  • Large scale coherent magnetohydrodynamic oscillations in a sunspot 
    Stangalini, Marco; Verth, G.; Fedun, V.; Aldhafeeri, A.A.; Jess, D.B.; Jafarzadeh, Shahin; Keys, P.H.; Fleck, B.; Terradas, J.; Murabito, M.; Ermolli, I.; Soler, R.; Giorgi, F.; MacBride, C.D. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Abstract Although theoretically predicted, the simultaneous excitation of several resonant modes in sunspots has not been observed. Like any harmonic oscillator, a solar magnetic flux tube can support a variety of resonances, ...
  • Linear Polarization Features in the Quiet-Sun Photosphere: Structure and Dynamics 
    Kianfar, S; Jafarzadeh, Shahin; Mirtorabi, MT; Riethmüller, T. L. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We present detailed characteristics of linear polarization features (LPFs) in the quiet-Sun photosphere from high-resolution observations obtained with SUNRISE/IMaX. We explore differently treated data with various noise ...