IIA Institutional Repository: Recent submissions

  • Seyfert galaxies: Nuclear radio structure and unification 
    Lal, D. V (Astronomical Society of India, 2002-09)
    We have observed a sample of Seyfert (Sy) galaxies with global Very Long Baseline Interferometry (VLBI) to test predictions of the unification scheme which hypothesizes that Sys of Type 1 and of Type 2 constitute a single ...
  • Recent observations of lES2344+514 and PSR 0355+54 with TACTIC Imaging Element 
    Tickoo, A. K; Dhar, V. K; Yadav, K. K; Rannot, R. C; Bhattacharyya, S; Chandra, P; Goyal, H. C; Kaul, C. L; Kaul, R. K; Kothari, M; Kotwal, S; Koul, R; Sahayanathan, S; Sapru, M. L; Sharma, M; Venugopal, K; Bhatt, N; Bhatt, C. L (Astronomical Society of India, 2002-09)
    The TACTIC Imaging Element has observed the active galaxy 1ES 2344+514 and the pulsar PSR 0355+54 during Oct-Nov, 2001. Analysis of the recorded events, collected for a period of 70 hours on both these sources reveals ...
  • Correlation between magnetic shear and magnetic tension in a solar active region 
    Venkatakrishnan, P; Narayanan, R. S; Prasad, N. D. N (Kluwer Academic Publishers, 1993-04)
    The difference between the magnetic tension and magnetic shear was calculated for four vector magnetograms of NOAA AR 4474. It was seen that this difference between the two independent angular measures of magnetic stress ...
  • Anomalous dust in the environment of Herbig Ae/Be stars 
    Gorti, U; Bhatt, H. C (European Southern Observatory, 1993-04)
    Photometric data in the UBVRI bands of Herbig Ae/Be stars have been analyzed to study the wavelength dependence of extinction to these objects. The color excess ratios E(U-B)/E(B-V), E(V-R)/E(B-V), E(V-I)/E(B-V) and ...
  • Filament activity in a quiet region flare 
    Sundararaman, K; Gupta, S. S; Selvendran, R (Indian Academy of Sciences, 1993-03)
    We have taken the case of a circular H-alpha filament observed on May 9, 1979 erupting into a double-ribbon flare associated with a nonspot region. The plage motions are responsible for the filament reorientation and, here ...
  • The Density Structure of a Galaxy Influenced by a Massive Companion 
    Namboodiri, P. M. S; Kochhar, R. K (Royal Astronomical Society, 1993-04-15)
    The tidal influence of a massive galaxy on a non-rotating spherical companion is studied using numerical simulations. The simulations use various values of mass ratio and velocity of collision while the pericentric distance ...
  • Alfvén vortices in nonuniform dusty magnetoplasmas 
    Shukla, P. K; Varma, R. K; Krishan, V; Mckenzie, J. F (The American Physical Society, 1993-01)
    The Alfvén waves are shown to be linearly coupled with finite-frequency convective cell modes in a nonuniform cold dusty magnetoplasma. The dynamics of weakly interacting finite-amplitude electromagnetic oscillations is ...
  • Characteristics of synchrotron Čerenkov radiation 
    Pratap, R; Sasidharan, K; Krishan, V (The American physical Society, 1993-01)
    A diagrammatic technique has been worked out in the framework of nonequilibrium statistical mechanics as developed by Prigogine and co-workers to tackle the problem of radiation emission from a relativistic electron in an ...
  • Onset of Hydrodynamic Non-Equilibrium in Helmet Streamers 
    Venkatakrishnan, P (Kluwer Academic Publishers, 1996-06)
    The steady-state solar wind solution is examined for different geometries of the flow tube that mimics a helmet streamer. Onset of non-equilibrium is seen whenever the spatial variation of the flow geometry crosses critical ...
  • Ellipsometry of Coelostat Coatings Using a Babinet Compensator: Simulation of the Experimental Accuracy 
    Sankarasubramanian, K; Venkatakrishnan, P (Kluwer Academic Publishers, 1996-08)
    The precise measurement of solar magnetic fields requires an accurate measurement of the Muller matrix of the optical components in the path of the light beam, which again requires a careful measurement of the optical ...
  • Spectral Variations of DY Cen 
    Giridhar, S; Kameswara Rao, N; Lambert, D. L (Indaian Academy of Sciences, 1996-06)
    Two high resolution spectra of the hot RCrB star DY Cen in the red region are compared. The photospheric absorption lines show a radial velocity variation of 12 km s(sup -1) between 1989 July and 1992 May. Emission components ...
  • Line profile variations in γ Doradus 
    Balona, L. A; Böhm, T; Foing, B. H; Ghosh, K. K; Janot-Pacheco, E; Krisciunas, K; Lagrange, A. M; Lawson, W. A; James, S. D; Baudrand, J; Catala, C; Dreux, M; Felenbok, P; Hearnshaw, J. B (Royal Astronomical Society, 1996-08)
    We present data from high-dispersion echelle spectra and simultaneous uvby photometry for γ Doradus. These data were obtained from several sites during 1994 November as part of the MUSICOS-94 campaign. The star has two ...
  • Metric Radio Observations and Ray-tracing Analysis of the Onset Phase of a Solar Eruptive Event 
    Kathiravan, C; Ramesh, R; Subramanian, K. R (University of Chicago Press, 2002-03)
    We report metric radio observations and the results obtained using two-dimensional ray-tracing analysis of the solar corona close to the onset phase of the exceptionally bright prominence eruption and the associated massive ...
  • Full resolution deconvolved images from the Mauritius Radio Telescope 
    Pandey, V. N; Oozeer, N; Shankar, N. U; Somanah, R (Astronomical Society of India, 2002-09)
  • A study of accretion discs around rapidly rotating neutron stars in general relativity and its applications to four low mass X-ray binaries 
    Bhattacharyya, S (E D P Sciences, 2002-02)
    We calculate the accretion disc temperature profiles, disc luminosities and boundary layer luminosities for rapidly rotating neutron stars considering the full effect of general relativity. We compare the theoretical values ...
  • A study of spatial structure of galactic open star clusters 
    Nilakshi; Sagar, R; Pandey, A. K; Mohan, V (E D P Sciences, 2002-02)
    In order to study the relation between the core and corona in galactic star clusters, the spatial structure of 38 rich open star clusters has been studied using radial density profiles derived from the photometric data of ...
  • delta Scuti stars in Praesepe. II. The STACC 1998 campaign - The spectroscopy 
    Dall, T. H; Frandsen, S; Lehmann, H; Anupama, G. C; Kambe, E; Handler, G; Kawanomoto, S; Watanabe, E; Fukata, M; Nagae, T; Horner, S (E D P Sciences, 2002-04)
    We present the results of a large international spectroscopic campaign on the delta Scuti star BN Cnc. Combining observations from five observatories taken over more than two weeks, we calculate line indices of the Hα line. ...
  • BVRIJHK photometry of post-AGB candidates 
    Fujii, T; Nakada, Y; Parthasarathy, M (E D P Sciences, 2002-04)
    BVRIJHK photometric observations are presented for 27 post-AGB candidates. Almost all objects show a double peaked SED curve in the optical to far-infrared wavelengths. Seventeen objects were classified as post-AGB stars ...
  • Change of rotation rates of sunspot groups during their lifetimes: Clues to the sites of origin of different flux tubes 
    Hiremath, K. M (E D P Sciences, 2002-05)
    From 103 years of data of non-recurrent sunspot groups and for the two sets (area <100 millionths of hemisphere and >100 millionths of hemisphere), irrespective of their life span, we compute rotation rates and rate of ...
  • Intranight optical monitoring of optically selected bright quasars 
    Sagar, R; Gopal-Krishna; Wiita, P. J (Royal Astronomical Society, 1996-08)
    As part of an ongoing programme to search for intranight optical variations, we report results for six radio-quiet and one radio-moderate, but all optically bright and luminous, quasi-stellar objects (QSOs), using the ...

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