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Browsing IIAP Publications by Author "Varghese, B. A"

Browsing IIAP Publications by Author "Varghese, B. A"

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  • A comparative study of finite-difference methods for radiative transfer problems. 
    Mohan Rao, D; Varghese, B. A; Srinivasa Rao, M (Elsevier, 1995-06)
    We have compared the numerical results of two widely used difference methods for the radiative transfer equation in plane-parallel medium. The Discrete Space theory (DS) is based on the direct first-order differential ...
  • Cooler and Hotter X-ray Bright Points from Hinode/XRT Observations 
    Kariyappa, R; DeLuca, E. E; Saar, S. H; Golub, L; Dame, L; Varghese, B. A (Astronomical Society of the Pacific, 2012-08)
    We use a 7-hour (17:00 UT - 24:00 UT) time sequence of soft X-ray images observed almost simultaneously in two filters (Ti_poly and Al_mesh) on April 14, 2007 with X-Ray Telescope (XRT) on-board the Hinode mission to ...
  • Cylindrical Hall – MHD Waves: A Nonlinear Solution 
    Krishan, V; Varghese, B. A (Springer Netherlands, 2008-01)
    The exact nonlinear cylindrical solution for incompressible Hall – magnetohydrodynamic (HMHD) waves, including dissipation, essentially from electron – neutral collisions, is obtained in a uniformly rotating, weakly ionized ...
  • Dynamical evolution of x-ray bright points with hinode/XRT 
    Kariyappa, R; Varghese, B. A; DeLuca, E. E; van Ballegooijen, A. A (Springer, 2010)
    We analyzed a 7-h long time sequence of soft X-ray images obtained on 14 April 2007 from a quiet region using the X-Ray Telescope (XRT) onboard Hinode. The aim was to observe intensity oscillations in coronal XBPs of ...
  • Effects of dust on the formation of lines in an expanding spherical medium 
    Peraiah, A; Varghese, B. A; Srinivasa Rao, M (The European Southern Observatory, 1987-06)
    A series of line profiles formed in a spherically symmetric and radially expanding atmosphere in which dust is present are computed, assuming that the dust scatters radiation isotropically. Two cases of dust distribution ...
  • Effects of temperature and velocity gradients on Doppler widths 
    Peraiah, A; Varghese, B. A (D. Reidel Publishing Co., 1986-10)
    The effects of gradients of temperature and expansion velocities on Doppler widths is investigated, and the emergent profiles of lines in different spherically symmetric media are calculated. The variations of the source ...
  • The Enhanced Coronal Green Line Intensity and the Magnetic Field Gradients 
    Ramesh, K. B; Nagabhushana, B. S; Varghese, B. A (Indian Academy of Sciences, 2000-12)
  • Global modes constituting the solar magnetic cycle. I - Search for 'dispersion relations' 
    Gokhale, M. H; Javaraiah, J; Kutty, K. N; Varghese, B. A (Springer Netherlands, 1992-03)
    The spherical-harmonic-Fourier (SHF) analysis of the sun's magnetic field inferred from the Greenwich sunspot data is refined and extended to include the full length (1874-1976) of the data on the magnetic tape provided ...
  • Green coronal intensity enhancements and their relation to the underlying photospheric/chromospheric activity 
    Ramesh, K. B; Nagabhushana, B. S; Varghese, B. A (Kluwer Academic Publishers, 1999-08)
    Analysis of the photospheric and chromospheric activity at the sites of enhanced 5303 Å coronal intensity revealed some important aspects of their association. We have examined the daily maps of 5303 Å coronal line intensity ...
  • Intensity oscillations and heating of the coronal X-ray bright points from Hinode/XRT 
    Kariyappa, R; Varghese, B. A (EDP Sciences, 2008-07)
    Aims. Our aim is to investigate the intensity oscillations in coronal X-ray Bright Points (XBPs). Methods. We analysed a 7 h long time sequence of the soft X-ray images obtained on April 14, 2007 with a 2 min cadence using ...
  • Irradiation effects in close binaries in an electron scattering medium 
    Varghese, B. A; Srinivasa Rao, M (Springer, 2016-03)
    In a close binary system, the effects of irradiation are studied from an extended surface of the secondary component on the atmosphere of the primary. Primary and the secondary components are assumed to have equal radii ...
  • Irradiation effects in close binary stars 
    Srinivasa Rao, M; Varghese, B. A (Anita Publications, 2004-12)
    We studied the reflection effect in 2-dimensional geometry to see how the field will change if we calculate the reflected radiation by the transfer equation in a close binary system. The reflected radiation is calculated from ...
  • Line Profiles in an Expanding Spherical Medium 
    Peraiah, A; Srinivasa Rao, M; Varghese, B. A (Indian Institute of Astrophysics, Bangalore, 1986)
    We have applied the discrete space theory of radiative with the integral operator technique to calculate the spectral line profiles formed in a spherically symmetric expanding stellar atmospheres. We calculated the source ...
  • Magnetic Activity and the Enhanced 5303 Ã Emission in Solar Active Regions 
    Ramesh, K. B; Nagabhushana, B. S; Varghese, B. A (Springer, 2001-03)
    Analysis of the intensity maps of Fexiv emission at λ=5303 Å obtained from the observations of ground-based coronagraphs during the sunspot minimum period 1985 and 1986 shows the persistent presence of localized strong ...
  • On the coronal lines 5303 A and 6374 A 
    Peraiah, A; Varghese, B. A (Springer, 1989-06)
    Theoretical calculations of the observed coronal emission line profiles of Fe XIV (5303 A) and Fe X (6374 A) ions, which are observed at the time of total solar eclipse, are presented. Baumbach's relation of electron density ...
  • Radiative transfer equation in spherical symmetry 
    Peraiah, A; Varghese, B. A (American Astronomical Society, 1985-03)
    A numerical solution of the radiative transfer equation in spherically symmetric geometry is presented using integral operators within the framework of the discrete space theory and expressing the specific intensity in ...
  • Radiative transfer equation in spherically-symmetric non-scattering media 
    Peraiah, A; Varghese, B. A (D. Reidel Publishing Co., 1984-12)
    The equation of radiative transfer in spherically symmetric shells with arbitrary internal sources is solved. The equation of transfer is integrated on a discrete grid of angle and radius. The size in angle coordinates is ...
  • Radiative Transfer Models of Dust Shells Around Post-AGB Stars 
    Surendiranath, R; Parthasarathy, M; Varghese, B. A (Springer, 2002-09)
    We present a radiative transfer analysis of circumstellar dust shells around the Post-AGB stars HD 179821, HD 56126, HD 101584 and early R star HD 100764, using the code DUSTY. Parameters like mass-loss, shell inner radius, ...
  • Radiative transfer with Compton scattering in spherically symmetric shells 
    Peraiah, A; Varghese, B. A (Astronomical Society of Japan, 1990)
    The radiative transfer equation with Compton scattering is solved for spherically symmetric shells. The purpose of the study is to determine how gamma rays or X-rays change their energies and how they become reflected and ...
  • Reflection effect in close binaries: effects of reflection on spectral lines 
    Srinivasa Rao, M; Varghese, B. A (Springer, 2014-02)
    Reflection effect phenomenon is studied on the formation of spectral lines in a close binary system when primary component has an extended atmosphere and the secondary component is a point source. Irradiation effect is ...

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