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Browsing IIAP Publications by Title

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  • Sunspot activity as originating in interference of the sun's global MHD oscillations 
    Gokhale, M. H; Javaraiah, J (Royal Astronomical Society, 1990-03)
    Spherical-harmonic-Fourier (SHF) analysis of sunspot activity during 1902-54 show that the sunspot occurrence probability p(theta, phi, t) is given by superposition of, mainly, axisymmetric even degree SHF modes of l not ...
  • Sunspot area catalog revisited: Daily cross-calibrated areas since 1874 
    Mandal, Sudip; Krivova, N. A; Solanki, S. K; Sinha, N; Banerjee, D (EDP Sciences, 2020-08)
    Context. Long and consistent sunspot area records are important for understanding long-term solar activity and variability. Multiple observatories around the globe have regularly recorded sunspot areas, but such individual ...
  • Sunspot drawings at Kodaikanal Observatory: a representative results on hemispheric sunspot numbers and area measurements 
    Ravindra, B; Kumaravel, P; Selvendran, R; Samuel, Joyce; Kumar, P; Nancy Jassoria; Navneeth, R. S (Springer, 2020-01)
    The importance of the periodicity in sunspot appearance was well recognized by the mid-19th century. Several observatories around the globe have made the record of sunspots in the form of drawings and preserved them safely ...
  • Sunspot Groups as Tracers of Sub-surface Processes 
    Gokhale, M. H (Indian Academy of Sciences, 2000-12)
    Data on sunspot groups have been quite useful for obtaining clues to several processes on global and local scales within the sun which lead to emergence of toroidal magnetic flux above the sun's surface. I present here ...
  • Sunspot Motions Associated with Flares 
    Sundararaman, K; Selvendran, R; Thiagarajan, R (Kluwer Academic Publishers, 1998-06)
    The evolution of five bipolar sunspot groups during their disk passage leading to flares are analysed and studied using Kodaikanal Observatory photoheliogram and spectroheliogram data. The changes in the orientation angle ...
  • Sunspot motions from a study of Kodaikanal and Mount Wilson observations 
    Howard, R. F; Sivaraman, K. R; Gupta, S. S; Gilman, P. I (International Astronomical Union, 1990)
    Results are presented of a study of the daily motions of individual sunspots and of sunspot groups on the basis of Kodaikanal and Mount Wilson white-light observations. A comparison of the two data sets show a good agreement ...
  • Sunspot rotation as a driver of major solar eruptions in the NOAA active region 12158 
    Vemareddy, P; Cheng, X; Ravindra, B (IOP Publishing, 2016-09-20)
    We studied the development conditions of sigmoid structure under the influence of the magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from ...
  • Sunspot seismology: accounting for magnetohydrodynamic wave processes using imaging spectropolarimetry 
    Rajaguru, S. P (Astronomical Society of India, 2011)
    E ects of acoustic wave absorption, mode conversion and transmission by a sunspot on the helioseismic inferences are widely discussed, yet accounting for them has proved di cult for lack of a consistent framework within ...
  • Sunspot sizes and the solar cycle: analysis using Kodaikanal white-light digitized data 
    Mandal, Sudip; Banerjee, D (IOP Publishing, 2016-10-20)
    Sizes of the sunspots vary widely during the progression of a solar cycle. Long-term variation studies of different sunspot sizes are key to better understand the underlying process of sunspot formation and their connection ...
  • Sunspots Data Analysis Using Time Series 
    Shaikh, Y. H; Khan, A. R; Iqbal, M. I; Behere, S. H; Bagare, S. P (World Scientific Publishing, 2008-09)
    The record of the sunspot number visible on the sun is regularly collected over the centuries by various observatories for studying the different factors influencing the sunspot cycle and solar activity. Sunspots appear ...
  • The Sunyaev-Zel Effect by Multiple Scattering: Numerical solution of the transfer equations 
    Sengupta, S (World Scientific Publishing Company, 2004-05-10)
    The radiative transfer equations for multiple inverse Compton scattering of the Cosmic Microwave Background Radiation (CMBR) by the hot intra-cluster electrons are solved numerically. The spherical isothermal and inhomogeneous ...
  • Sunyaev-Zel'dovich distortion from early galactic winds 
    Majumdar, S; Nath, B. B; Chiba, M (Royal Astronomical Society, 2001-07)
    We consider the distortion in the cosmic microwave background (CMB) resulting from galactic winds at high redshift. Winds outflowing from galaxies have been hypothesized to be possible sources of metals in the intergalactic ...
  • Supercritical winds from cool 'canonical' stars caused by evolution on the main sequence 
    Venkatakrishnan, P (D. Reidel Publishing Co., 1986-02)
    Even the very slow expansion of a star's radius due to evolution on the Main Sequence is shown to be supercritical for cool stars without coronae. Since steady sphericaily-symmetric supercitical solutions are theoretically ...
  • The superfluid vacuum state, time-varying cosmological constant, and nonsingular cosmological models 
    Sinha, K. P; Sivaram, C; Sudarshan, E. C. G (Springer, 1976)
    Some cosmological consequences of the superfluid vacuum state developed previously by the authors are discussed, particularly with regard to the initial stages of the universe. The transition temperature of the hadronic ...
  • Supergranulation and its Activity Dependence 
    Paniveni, U; Krishan, V; Singh, J; Srikanth, R (Cambridge University Press, 2011-08)
    We study the complexity of supergranular cells using the intensity patterns obtained at the Kodaikanal solar observatory during the solar maximum. Our data consists of visually identified supergranular cells, from which a ...
  • Supergranulation and its Activity Dependence 
    Paniveni, U; Krishan, V; Singh, J; Srikanth, R (Cambridge University Press, 2011-08)
    We study the complexity of supergranular cells using the intensity patterns obtained at the Kodaikanal solar observatory during the solar maximum. Our data consists of visually identified supergranular cells, from which a ...
  • Supernova 1987A and its Implications to Neutrino Physics 
    Murthy, M. V. N (Indian Institute of Astrophysics, 1988)
    We review the reported neutrino events from the supernova SN 1987A and present a critical analysis of these events for their implications on the mechanism of stellar collapse as well as for neutrino physics.
  • Supernova 1987A in LMC : Infrared Observations 
    Bhatt, H. C (Indian Institute of Astrophysics, 1988)
    Results obtained from infrared observations of SN 1987A have been summarized. The supernova developed near-infrared excesses with a characteristic temperature ~1250 k beginning around March 15, 1987. Infrared speckle ...
  • Supernova 1987A: Ten years after 
    Datta, B (Indian Academy of Sciences, 1997-11)
  • Supernova 1991T in NGC 4527 
    Sivaraman, K. R; Prabhu, T. P; Anupama, G. C; Schmeer, P; Smith, H; Royer, R; Lubcke, G; Villi, M; Cortini, G (Smithsonian Astrophysical Observatory, 1991-04)

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