IIA Institutional Repository: Recent submissions

  • Low Frequency Radio Emission from the 'Quiet Sun' 
    Ramesh, R (Indian Academy of Sciences, 2000-12)
    We present observations of the 'quiet' Sun close to the recent solar minimum (Cycle 22), with the Gauribidanur radioheliograph. Our main conclusion is that coronal streamers also influence the observed radio brightness ...
  • 22-year Periodicity in the Solar Differential Rotation 
    Javaraiah, J (Journal of Astrophysics and Astronomy, Vol. 21, No. 3 – 4, pp. 167 - 170, 2000-12)
    Using the data on sunspot groups compiled during 1879- 1975, we determined variations in the differential rotation coefficients A and Β during the solar cycle. The variation in the equatorial rotation rate A is found ...
  • Polarization measurements of the luminous blue variable HR Carinae 
    Parthasarathy, M; Jain, S. K; Bhatt, H. C (European Southern Observatory, 2000-03)
    We have made BVRI polarization measurements of HR Car on ten occasions during the period JD 2447919 to JD 2449014. All our observations are on the rising part of the light curve. We find the presence of intrinsic variable ...
  • High-resolution spectroscopy of V854 Cen in decline - absorption and emission lines of C2 molecules 
    Kameswara Rao, N; Lambert, D. L (Royal Astronomical Society, 2000-04)
    High-resolution optical spectra of the R Coronae Borealis (RCB) star V854 Centauri in the early stages of a decline show, in addition to the features reported for other RCBs in decline, narrow absorption lines from the C2 ...
  • Constraints on structure formation models from the Sunyaev-Zel'dovich effect 
    Majumdar, S; Subrahmanyan, R (Royal Astronomical Society, 2000-03)
    In the context of cold dark matter (CDM) cosmological models, we have simulated images of the brightness temperature fluctuations in the cosmic microwave background (CMB) sky owing to the Sunyaev–Zel'dovich (S–Z) effect ...
  • The Raman effect and Krishnan's diary 
    Mallik, D. C. V (The Royal Society, 2000-01)
    K.S. Krishnan, F.R.S. (1898-1961) is one of the most distinguished Indian scientists of this century. His collaboration with Sir C.V. Raman on the scattering of light by liquids--a collaboration which Raman described as ...
  • Hydromagnetic surface waves in compressible moving cylindrical flux tubes 
    Satya Narayanan, A (IOP Publishing, 1991-04)
    The dispersive characteristics of hydromagnetic surface waves along the boundary of a moving compressible cylindrical plasma column of radius 'a' surrounded by a compressible stationary column are studied
  • 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 ...
  • Results from Kodaikanal Synoptic Observations 
    Sivaraman, K. R (Indian Academy of Sciences, 2000-12)
    The synoptic observations of Kodaikanal form one of the longest unbroken solar data from the beginning of the 20th century to the present day, and consists of the white light and monochromatic images of the sun. In this ...
  • Low-Frequency Radio Observations of the Angular Broadening of the Crab Nebula Due to a Coronal Mass Ejection 
    Ramesh, R; Kathiravan, C; Sastry, Ch. V (The American Astronomical Society, 2001-02)
    We report two-dimensional, low-frequency radio observations of the angular broadening of the Crab Nebula (Taurus A) due to a coronal mass ejection (CME), at a distance of ~41 Rsolar from the Sun. The estimated electron ...
  • Collisions of galaxies of different masses, forms and sizes 
    Namboodiri, P. M. S; Sastry, K. S; Narasimhan, K. S. V. S (Springer, 2001-03)
    We study the tidal effects of close collisions between two spherical galaxies of various mass and mass distributions by numerical simulations. The galaxies are represented by polytropes of indices n=4 and n=0 which denote ...
  • Convective collapse and overstable oscillations in solar flux tubes 
    Hasan, S. S (European Space Egency, 1984-11)
    The collapse of solar flux tubes by a convective instability is investigated. At the initial epoch it is assumed that the flux tube is in hydrostatic equilibrium and that it has the same temperature as the ambient medium. ...
  • HiRES - A high-resolution stigmatic extreme ultraviolet spectroheliometer for studies of the fine-scale structure of the solar chromosphere, transition region, and corona 
    Timothy, J. G; Berger, T. E; Morgan, J. S; Walker, A. B. C; Jain, S. K; Saxena, A. K; Bhattacharyya, J. C; Huber, M. C. E; Tondello, G; Naletto, G (SPIE, 1991-08)
    HiRES is a high-resolution stigmatic EUV spectroheliometer whose 45-cm Gregory telescope is coupled to a spectrometer employing a single toroidal diffraction grating and an imaging pulse-counting multianode microchannel ...
  • Personal - Computer based spectrum scanner 
    Srinivasan, R; Surendiranath, R (Council of Scientific and Industrial Research, 1991-04)
    The advent of personal computers (PC) has resulted in flexible and low cost solution for the control and acquisition of data from spectrum scanner used with optical telescopes. The PC enables user- friendly dialogue for ...
  • Torsion, wormholes, and the problem of the Cosmological constant 
    de Sabbata, V; Sivaram, C (Springer, 1991-02)
    We consider the effect of torsion in the early universe to see if it is possible to explain the small value (if not zero) of the Cosmological constant at the present time. For the gauge-theoretic formulation of the ...
  • The justice delayed the case of Lise Meitner 
    Krishan, V (Indian Academy of Sciences, 1991-06)
  • Effect of beam-plasma instabilities on accretion disk flares 
    Krishan, V; Wiita, P. J; Ramadurai, S (European Southern Observatory, 2000-04)
    We show that a certain class of flare models for variability from accretion disk coronae are subject to beam-plasma instabilities. These instabilities can prevent significant direct acceleration and greatly reduce the ...
  • The Equivalence Principle and Quantum Mechanics 
    Unnikrishnan, C. S (World Scientific Publishing Company, 2002-06)
    There have been many speculations that the equivalence principle might be violated in situations involving quantum systems in a classical gravitational field. Also, several authors have stated that experiments involving ...
  • The Accelero-Magnetic Field, Thomas Precession and an Equivalence Principle for Spin 
    Unnikrishnan, C. S (World Scientific Publishing Company, 2001-03)
    In the weak field limit of Einstein gravity, there are gravitational analogues of the vector potential and the magnetic field. The equivalence principle guides us to a magnetic-like interaction arising from inertial ...
  • Antiquity of the vedic calendar 
    Abhyankar, K. D (Astronomical Society of India, 1998-03)
    Taking guidance from Vedanga jyotis, it is found that in ancient India the sacrificial year started near the winter solstice. As the position of the winter solstice retrogrades by 1 degree in about 71 years due to the ...

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