IIAP Publications: Recent submissions

  • Photometric study of the RS CVn binary DM Ursa Majoris 
    Mohin, S; Raveendran, A. V (EDP Sciences, 1992-03)
    Differential BV photometry of DM UMa obtained on 77 nights during the six observing seasons over the years 1984-90 is presented. The phases of the light minima observed during 1988-90 are found to be nearly the same. The ...
  • EXOSAT observations of the broad-line radio galaxy 3C 382 
    Ghosh, K. K; Soundararajaperumal, S (University of Chicago Press, 1992-04)
    Results are presented of numerous X-ray observations of the broad-line radio galaxy 3C 382 carried out with Exosat between 1983 and 1985, with emphasis on a major outburst of this galaxy in 1985. During the outburst, both ...
  • Spatio-temporal fluctuations in He I 10830 A line parameters - Evidence for spicule formation 
    Venkatakrishnan, P; Jain, S. K; Singh, J; Recely, F; Livingston, W. C (Springer Netherlands, 1992-03)
    The equivalent width, line depth, line width, and Doppler shift of the He i 10830 Å line were extracted from two time series of spectra. Scatter plots of time-averaged line depth, line width, and Doppler shifts, as well ...
  • 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 ...
  • X-ray spectrum of NGC 3783 - Detection of soft excess and an emission line 
    Ghosh, K. K; Soundararajaperumal, S; Kalai Selvi, M; Sivarani, T (EDP Sciences, 1992-02)
    Results of the X-ray (0.1-10 keV) spectral analysis of the Seyfert I galaxy, NGC 3783, which was observed with EXOSAT on three epochs between 1983 and 1985, are presented here. No low energy absorption, intrinsic to the ...
  • The Mauritius Radiotelescope 
    Golap, K; Issur, N. H; Somanah, R; Dodson, R; Modgekar, M; Sachdev, S; Shankar, N. Udaya; Sastry, Ch. V (Springer Netherlands, 1995-06)
    The Mauritius Radiotelescope (MRT) is a T-shaped array of helical antennas with a 2048 m EW arm and a 890 m South arm. The primary objective of the telescope is to produce a sky survey in the declination zone -15° to -65° ...
  • Probable binary open star clusters in the Galaxy. 
    Subramaniam, A; Gorti, U; Sagar, R; Bhatt, H. C (EDP Science, 1995-10)
    The existence of double/binary clusters in the Magellanic Clouds is fairly well established, whereas only one such pair, h + χ Persei, is known in the Galaxy. From the catalogues of open clusters of the Galaxy, we have ...
  • Galaxy dynamics with small computers: Some results on tidal interactions. 
    Kochhar, R. K; Namboodiri, P. M. S (Springer Netherlands, 1995-06)
    Numerical simulations with a small computer have been performed to investigate the tidal influence of a larger galaxy on a smaller companion. A criterion is developed for disruption of the satellite galaxy. The behaviour ...
  • The synthesis of Al-26 during combined hydrogen and helium-burning reactions 
    Goswami, A; Ramadurai, S; Duorah, H. L (Springer Netherlands, 1992-02)
    The synthesis of Al-26 during combined hydrogen and helium-burning processes in high temperature and density conditions is studied. The possible sites for these processes are believed to be the neutron star surfaces where ...
  • Distribution of ionized gas in X-ray bright early-type galaxies. 
    Singh, K. P; Bhat, P. N; Prabhu, T. P; Kembhavi, A. K (Springer, 1995-10)
    We report imaging observations of Hα+[N II] nebulosities in seven early type galaxies viz., NGC 1399, NGC 1600, NGC 2563, NGC 4203, NGC 4636, NGC 4753 and NGC 5044. These are primarily X-ray bright galaxies which are the ...
  • On the Large-Scale Diffuse Magnetic Field of the Sun 
    Dikpati, M; Choudhuri, A. R (Springer, 1995-10)
    Although the sunspots migrate towards the equator, the large-scale weak diffuse magnetic fields of the Sun migrate poleward with the solar cycle, the polar field reversing at the time of the sunspot maxima. We apply the ...
  • X-ray continuum with an iron emission line from the radio-quiet quasar PHL 909 
    Ghosh, K. K; Soundararajaperumal, S (University of Chicago Press, 1992-04)
    Results of the spectral analysis of the X-ray (0.1-10 keV) spectrum of the radio-quiet quasar, PHL 909, are presented. A spectrum of this quasar, which was observed on 1984/349, was obtained from the Exosat archives. ...
  • The role of Compton and Raman scattering in the quasar continuum 
    Gangadhara, R. T; Krishan, V (Blackwell Publishing, 1992-05)
    There are three ways in which an electromagnetic wave can undergo scattering in a plasma: (1) when the scattering of radiation occurs by a single electron, it is called Compton Scattering; (2) if it occurs by a longitudinal ...
  • Global modes constituting the solar magnetic cycle. II - Phases, 'geometrical eigenmodes', and coupling of field behaviour in different latitudes 
    Gokhale, M. H; Javaraiah, J (Springer Netherlands, 1992-04)
    We show that the axisymmetric odd degree SHF modes of 21.4-yr periodicity and degrees l le 29 in the solar magnetic field (as inferred from sunspot data during 1874–1976), are at least approximately stationary. Among the ...
  • Magnetic shear in flaring regions. I - Quantitative evaluation of the change in shear 
    Sivaraman, K. R; Rausaria, R. R; Aleem, S. M (Springer Netherlands, 1992-04)
    We have evaluated the shear angle of the neutral line of the non-potential magnetic field for one or two days prior to and after the flare event for 10 cases. We have used the Hagr filament positions to evaluate the shear ...
  • Gain calibration of CCD systems at VBO 
    Prabhu, T. P; Mayya, Y. D; Anupama, G. C (Indian Academy of Sciences, 1992-03)
    The system gain of two CCD systems in regular use at the Vainu Bappu Observatory, Kavalur, is determined at a few gain settings. The procedure used for the determination of system gain and base-level noise is described in ...
  • Effects of rotation on the colours and line indices of stars. VI - The reality of the blue straggler phenomenon 
    D'Souza, J; Mathew, Annamma; Rajamohan, R (Indian Academy of Sciences, 1992-03)
    The effect of rotation on the observed colors of stars has been considered as a possible cause for the blue straggler phenomenon in clusters listed by Mermilliod (1982). It appears that this phenomenon is definitely not ...
  • Effects of rotation on the colours and line indices of stars. V - The ZRMS and the ZRZAMS 
    Mathew, Annamma; Rajamohan, R (Indian Academy of Sciences, 1992-03)
    The observed uvby and H-beta indices of member stars of the Hyades and Praesepe clusters are analyzed in detail for rotation. The slopes of the rotation effects observed are utilized to determine the zero rotation main ...
  • The solar dynamo with meridional circulation. 
    Choudhuri, A. R; Schussler, M; Dikpati, M (1995-11)
    We show that meridional circulation can have a profound influence on dynamo models for the solar cycle. Motivated by the observed tilt angles of sunspot groups we assume that the generation of the poloidal field takes place ...
  • Kinetic Equilibria of Accretion Discs 
    Bhaskaran, P; Krishan, V (Springer, 1995-10)
    A kinetic description of the equilibrium structure of accretion disc plasma is presented. It is possible to have an equilibrium configuration for a stationary axisymmetric gravitating plasma disc with spatial gradients in ...

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