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Browsing by Subject "Sun: photosphere"

Browsing by Subject "Sun: photosphere"

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  • 3D Simulations of realistic power halos in magnetohydrostatic sunspot atmospheres: linking theory and observation 
    Rijs, C; Rajaguru, S. P; Przybylski, D; Moradi, H; Cally, P. S; Shelyag, S (IOP Publishing, 2016-01)
    The well-observed acoustic halo is an enhancement in time-averaged Doppler velocity and intensity power with respect to quiet-Sun values that is prominent for the weak and highly inclined field around the penumbra ...
  • The Aditya-L1 mission of ISRO 
    Tripathi, Durgesh; Chakrabarty, D; Nandi, A; Prasad, B. R; Ramaprakash, A. N; Shaji, Nigar; Sankarasubramanian, K; Satheesh Thampi, R; Yadav, V. K (Cambridge University Press on behalf of International Astronomical Union, 2023)
    The Aditya-L1 is the first space-based solar observatory of the Indian Space Research Organization (ISRO). The spacecraft will carry seven payloads providing uninterrupted observations of the Sun from the first Lagrangian ...
  • Analysis of a fragmenting sunspot using hinode observations 
    Louis, R. E; Ravindra, B; Mathew, S. K; Bellot Rubio, L. R; Bayanna, A. R; Venkatakrishnan, P (IOP Publishing, 2012-08-10)
    We employ high-resolution filtergrams and polarimetric measurements from Hinode to follow the evolution of a sunspot for eight days starting on 2007 June 28. The imaging data were corrected for intensity gradients, projection ...
  • Analysis of full-disc Ca II K spectroheliograms III. Plage area composite series covering 1892–2019 
    Chatzistergos, Theodosios; Ermolli, Ilaria; Krivova, Natalie A; Solanki, Sami K; Banerjee, D; Barata, Teresa; Belik, Marcel; Gafeira, Ricardo; Garcia, Adriana; Hanaoka, Yoichiro; Manjunath, H; Klimes, Jan; Korokhin, Viktor V; Lourenço, Ana; Malherbe, Jean-Marie; Marchenko, Gennady P; Peixinho, Nuno; Sakurai, Takashi; Tlatov, Andrey G (EDP Sciences, 2020-07)
    Context. Studies of long-term solar activity and variability require knowledge of the past evolution of the solar surface magnetism. The archives of full-disc Ca II K observations that have been performed more or less ...
  • Analysis of sudden variations in photospheric magnetic fields during a large flare and their influences in the solar atmosphere 
    Brajesh, Kumar; Raja Bayanna, A; Venkatakrishnan, P; Kuchandy Mathew, S (IOP Publishing, 2016-08)
    The solar active region NOAA 11719 produced a large two-ribbon flare on 2013 April 11. We have investigated sudden variations in the photospheric magnetic fields in this active region during the flare by employing magnetograms ...
  • Contribution of Field Strength Gradients to the Net Vertical Current of Active Regions 
    Vemareddy, P (IOP Publishing, 2017-12)
    We examined the contribution of fi eld strength gradients for the degree of net vertical current ( NVC ) neutralization in active regions ( ARs ) . We used photospheric vector magnetic fi eld observations of ...
  • Data-driven Simulations of Magnetic Field Evolution in Active Region 11429: Magneto-frictional Method Using PENCIL CODE 
    Vemareddy, P; Warnecke, Jorn; Bourdin, Ph. A (IOP Publishing, 2024-02)
    Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short timescales. As of now there exist no regular measurements of coronal magnetic fields, and therefore generating the coronal ...
  • Dynamics of the Solar Magnetic Bright Points Derived from Their Horizontal Motions 
    Pradeep Chitta, L; van Ballegooijen, A. A; Rouppe van der Voort, L; DeLuca, E. E; Kariyappa, R (IOP Publishing, 2012-06-10)
    The subarcsecond bright points (BPs) associated with the small-scale magnetic fields in the lower solar atmosphere are advected by the evolution of the photospheric granules. We measure various quantities related to the ...
  • Flux tube model in the solar atmosphere 
    Sen, Samrat; Mangalam, A (Cambridge University Press, 2018-02)
    We construct two classes of the magnetohydrostatic equilibria of the axisymmetric flux tubes with twisted magnetic fields in the stratified solar atmosphere that span from the photosphere to the transition region. We built ...
  • Generation of Magnetic Structures on the Solar Photosphere 
    Gangadhara, R. T; Krishan, V; Bhowmick, A. K; Chitre, S. M (IOP Publishing, 2014-06-20)
    The lower solar atmosphere is a partially ionized plasma consisting of electrons, ions, and neutral atoms. In this, which is essentially a three-fluid system, the Hall effect arises from the treatment of the electrons and ...
  • Horizontal flows in active regions from ring-diagram and local correlation tracking methods 
    Jain, K; Tripathy, S. C; Ravindra, B; Komm, R; Hill, F (IOP Publishing, 2016-01)
    Continuous high-cadence and high spatial resolution Dopplergrams allow us to study subsurface dynamics that may be further extended to explore precursors of visible solar activity on the surface. Since the p -mode ...
  • Investigation of helicity and energy flux transport in three emerging solar active regions 
    Vemareddy, P (IOP Publishing, 2015-06-20)
    We report the results of an investigation of helicity and energy flux transport from three emerging solar active regions (ARs). Using time sequence vector magnetic field observations obtained from the Helioseismic Magnetic ...
  • Kodaikanal digitized white-light data archive (1921-2011): Analysis of various solar cycle features 
    Mandal, Sudip; Hegde, M; Samanta, T; Hazra, G; Banerjee, D; Ravindra, B (EDP Sciences, 2017-05)
    Context. Long-term sunspot observations are key to understanding and predicting the solar activities and its effects on space weather. Consistent observations, which are crucial for long-term variations studies, are generally ...
  • Latitude Distribution of Sunspots: Analysis Using Sunspot Data and a Dynamo Model 
    Mandal, Sudip; Karak, B. B; Banerjee, D (2017-12)
    In this paper, we explore the evolution of sunspot latitude distribution and explore its relations with the cycle strength. With the progress of the solar cycle, the distributions in two hemispheres from mid-latitudes ...
  • Long-term Evolution of Magnetic Field Proxies as Deduced from Archival Data 
    Banerjee, D; Bibhuti Kumar Jha; Mandal, Sudip; Chatterjee, Subhamoy; Hegde, M; KoSO Digitization Team (Cambridge University Press on behalf of International Astronomical Union, 2023)
    Regular observations of the solar magnetic field are available only for about the last five cycles. Thus, to understand the origin of the variation of the solar magnetic field, it is essential to reconstruct the magnetic ...
  • Magnetic fields and the supply of low-frequency acoustic wave energy to the solar chromosphere 
    Rajaguru, S. P; Sangeetha, C. R; Tripathi, Durgesh (IOP Publishing, 2019-02-01)
    The problem of solar chromospheric heating remains a challenging one with wider implications for stellar physics. Several studies in the recent past have shown that small-scale inclined magnetic field elements channel ...
  • Model of a fluxtube with a twisted magnetic field in the stratified solar atmosphere 
    Sen, Samrat; Mangalam, A (Elsevier B.V, 2018-01-15)
    We build a single vertical straight magnetic fluxtube spanning the solar photosphere and the transition region which does not expand with height. We assume that the fluxtube containing twisted magnetic fields is in ...
  • Molecular Line Polarization in the Solar Atmosphere: MGH Lines 
    Mohan Rao, D; Rangarajan, K. E (The American Astronomical Society, 1999-10)
    The polarimetric observations of the quiet Sun show linear polarization in molecular lines of C_2, MgH, etc. The molecular lines are very faint in the intensity spectrum. We propose that the polarization is caused by ...
  • Nature of helicity injection in non-erupting solar active regions 
    Vemareddy, P (Oxford University Press on behalf of Royal Astronomical Society, 2022-10)
    Using time-sequence vector magnetic field and coronal observations from Solar Dynamics Observatory, we report the observations of the magnetic field evolution and coronal activity in four emerging active regions (ARs). ...
  • Nonlinear Force-free Field Modeling of the Solar Magnetic Carpet and Comparison with SDO/HMI and Sunrise/IMaX Observations 
    Chitta, L. P; Kariyappa, R; van Ballegooijen, A. A; DeLuca, E. E; Solanki, S. K (IOP Publishing, 2014-10-01)
    In the quiet solar photosphere, the mixed polarity fields form a magnetic carpet that continuously evolves due to dynamical interaction between the convective motions and magnetic field. This interplay is a viable source ...

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