Publications of Astronomical Society of India: Recent submissions

  • Steady parts of rotation and magnetic field in the sun's convective envelope 
    Hiremath, K. M; Gokhale, M. H (Astronomical Society of India, 1996)
    We use the full set of Chandrasekhar's (1956) MHD equations for determining the steady parts of rotation and poloidal as well as toroidal magnetic field, in the Sun's convective envelope assuming incompressibility. The ...
  • Modelling sunspot equilibrium through a solution of the time dependent MHD equations 
    Gangadhara, R. T; Hasan, S. S (Astronomical Society of India, 1996)
    We numerically simulate the dynamical relaxation to equilibrium of a sunspot. Treating the sunspot as a thick axisymmetric flux tube in cylindrical geometry, we solve the time dependent MHD equation to examine the evolution ...
  • Plasma diagnostics for SUMER on board the SOHO mission 
    Dwivedi, B. N (Astronomical Society of India, 1996)
    We highlight a rich source of high-resolution EUV observations that the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument, on board the SOHO mission, is capable of making in the broad spectral range ...
  • Solar models with helioseismologically correct sound speed profile 
    Ajukov, S. V; Baturin, V. A (Astronomical Society of India, 1996)
    The problem of computation of the model of the present Sun with given sound speed profile in the solar radiative zone is considered. It is shown that the chemical composition is still a free parameter but the entropy of ...
  • Wave leakage in a magnetized isothermal atmosphere 
    Banerjee, D; Hasan, S. S; Christensen-Dalsgaard, J (Astronomical Society of India, 1996)
    The present investigation is a continuation of earlier work by Hasan & christensen-Dalsgaard (1992) and Banerjee, Hasan & Christensen-Dalsgaard(1995), where the interaction of various elementary modes in a stratified ...
  • On the accuracy of opacity interpolation schemes 
    Houdek, G; Rogl, J (Astronomical Society of India, 1996)
    We have investigated some of the properties and consequences of interpolation in opacity tables. In particular, we were interested in the estimate of the maximum interpolation errors, where they occur in the tables, and ...
  • Long-period oscillations of the sun's interior 
    Davila, J. M; Chitre, S. M (Astronomical Society of India, 1996)
    The long-period modes of a differentially rotating, solar-type star are consided. Two modes are found. The non-axisymmetric modes are Rossby waves, also known as r-modes, with the Coriolis force as the dominant restoring ...
  • Asteroseismological calibration of open clusters 
    Audard, N; Brown, T. M; Christensen-Dalsgaard, J; Frandsen, S; Kjeldsen, H (Astronomical Society of India, 1996)
    Combining classical and seismological data permits one to perform a calibration of stars, and therefore to improve the estimate of their fundamental parameters. We present preliminary results of the calibration of stars ...
  • Structure of turbulence in the solar convection zone 
    Krishan, V (Astronomical Society of India, 1996)
    Based on the inverse cascade of energy in a turbulent medium, a model of the solar granulation, encompassing all spatial scales, has been proposed. The predicted spatial energy distribution tends to agree fairly well with ...
  • Some aspects of the interpretation of frequency splitting data 
    Wilson, P. R (Astronomical Society of India, 1996)
    Many dynamo and dynamical models of the convection Zone require that the angular velocity be approximately constant on cylinders concentric about the rotation axis ('constant-on-cylinders'). However, inferences from the ...
  • Magnetic fields in the sun's interior: What do we know about them? 
    Choudhuri, A. R (Astronomical Society of India, 1996)
    The surface observations of the solar magnetic fields put some constraints on the possible magnetic configurations in the Sun's interior. It is currently believed that the solar magnetic fields are generated by a dynamo ...
  • The influence of chromospheric magnetism on oscillation frequencies 
    Roberts, B (Astronomical Society of India, 1996)
    The influence of chromospheric magnetism on p- and f-modes is examined. The magnetism is modelled as a horizontal canopy field, embedded in an isothermal atmosphere, overlying a field-free polytropic convection zone. Both ...
  • BiSON observations, their application to the rotation of the solar interior and to excitation mechanisms - the advantages of long, continuous time series 
    Elsworth, Y (Astronomical Society of India, 1996)
    The Birmingham Solar Oscillations group runs the so-called BiSON network. As the network has been operational since 1981 we have the great advantage of long, well-filled, historical datasets. These data have been put to ...
  • Using solar oscillations to constrain the equation of state and low-temperature opacities 
    Guzik, J. A; Cox, A. N; Swenson, F. J (Astronomical Society of India, 1996)
    Because thousands of solar p-mode oscillation frequencies have been measured to high accuracy, direct comparisons between calculated and observed frequencies are an excellent means of testing solar interior physics. Here ...
  • Helioseismic diagnosis of the equation of state 
    Dappen, W (Astronomical Society of India, 1996)
    The helioseismic verification of major nonideal effects in the equation of state of solar matter has become well established. The dominant contribution is the Coulomb pressure, conventionally described in the Debye-Huckel ...
  • Solar structure as revealed by 1 year LOWL data 
    Basu, S; Christensen-Dalsgaard, J; Schou, J; Thompson, M. J; Tomczyk, S (Astronomical Society of India, 1996)
    We have used solar frequencies obtained form 1 year of observations with LOWL instrument to investigate the radial stratification of the Sun. Models which include the diffusion of helium and heavy elements below the solar ...
  • Solar neutrino flux variation and its implications 
    Raychaudhuri, Probhas (Astronomical Society of India, 1996)
    Considering the solar neutrino flux data during the period from June 1989 to April 1992 from four solar neutrino experiments (Cl Solar neutrino experiment, SAGE I & II, GALLEX, Kamiokande II & III) we suggest that the ...
  • Seismic probing of the solar core 
    Dziembowski, W. A (Astronomical Society of India, 1996)
    Only a small fraction of the solar p-modes have frequencies with any measurable sensitivity to the core structure. Nevertheless an accurate seismic sounding with such modes alone is possible. This requires a high-precision ...
  • Effects on solar structure of opacity changes 
    Tripathy, S. C; Christensen-Dalsgaard, J (Astronomical Society of India, 1996)
    We investigate the sensitivity of solar structure to localized changes in opacity by considering differences between models computed with locally modified opacity and unmodified references models. The results confirm that ...
  • The effect of p-modes on thin magnetic flux tubes 
    Hasan, S. S; Bogdan, T. J (Astronomical Society of India, 1996)
    We examine the effect of p-modes impinging on thin magnetic flux tubes. The aim of the study is to see whether global p-modes can excite wave motions of significant amplitude in a magnetic flux tube. For simplicity we treat ...

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