IIA Institutional Repository: Recent submissions

  • Duration of Polar Activity Cycles and Their Relation to Sunspot Activity 
    Makarov, V. I; Tlatov, A. G; Sivaraman, K. R (Springer, 2003-05)
    We have defined the duration of polar magnetic activity as the time interval between two successive polar reversals. The epochs of the polarity reversals of the magnetic field at the poles of the Sun have been determined ...
  • When does the polar activity cycle start? 
    Makarov, V. I; Tlatov, A. G; Sivaraman, K. R (WILEY-VCH Verlag GmbH & Co., 2003-05)
  • Photon polarization in np fusion 
    Ramachandran, G; Deepak, P. N; Kumar, S. P (Institute of Physics Publishing Ltd., 2003-06)
    A model-independent irreducible tensor formalism is developed to discuss photon polarization in np fusion. It is shown that photon polarization arising out of the interference of the dominant isovector M1 amplitude at ...
  • The relaxation time in spherical galaxy simulations 
    Namboodiri, P. M. S (International Astronomical Union, 2003)
    The relaxation time of a spherical galaxy with various density distributions has been evaluated using numerical simulations. The results indicate that the relaxation time is weakly dependent on the density of the galaxies ...
  • Influence of correlation effects on the magnetic dipole hyperfine interaction in the low-lying states of Ca+ 
    Sahoo, B. K; Chaudhuri, R. K; Das, B. P; Majumder, S; Merlitz, H; Mahapatra, U. S; Mukherjee, D (Institute of Physics Publishing Ltd., 2003-05-28)
    The relativistic coupled cluster theory is employed to calculate the hyperfine structure of the 2S 1/2, 2P 1/2, 2P 3/2, 2D 3/2 and 2D 5/2 states of singly ionized calcium. The importance of correlation effects is highlighted. ...
  • First evidence for anomalous thick crust beneath mid-Archean western Dharwar craton 
    Gupta, S; Rai, S. S; Prakasam, K. S; Srinagesh, D; Chadha, R. K; Priestley, K; Gaur, V. K (Indian Academy of Sciences, 2003-05-10)
    We report an anomalous present day crustal thickness of 43–52 km beneath the 3.4–3.0 Ga mid-Archean segment of the western Dharwar craton (WDC) undisturbed by Proterozoic events. In contrast, adjoining late-Archean ...
  • A Revised Calibration of the M-V-W(O I 7774) Relationship using Hipparcos Data: Its Application to Cepheids and Evolved Stars 
    Ferro, A. A; Giridhar, S; Arellano, E. R (Instituto de Astronomía, Universidad Nacional Autónoma de México, 2003-04)
    A new calibration of the MV-W(O I 7774) relationship has been calculated using better reddening and distance estimates for a sample of 27 calibrator stars of spectral types A to G, based on accurate parallaxes and proper ...
  • Optical interferometric observations of a transient event of 1986 March 13 in the coma of Comet Halley 
    Prasad, D. C; Chandrasekhar, T; Desai, J. N; Ashok, N. M; Krishan, V (Indian Academy of Sciences, 1989-03)
    During the recent apparition of Comet Halley in 1985-86, a transient ionic event in the form of a blob of H2O(+) emission was recorded in the coma at about 0 h UT on March 13, 1986. Observations were carried out using a ...
  • The 1985 outburst of RS Ophiuchi - Spectroscopic results 
    Anupama, G. C; Prabhu, T. P (Indian Academy of Sciences, 1989-09)
    Results are reported from visual spectroscopy of the recurrent nova RS Oph, obtained with a Cassegrain spectrograph on the 102-cm reflector at Vainu Bappu Observatory in February-May 1985 (days 32-108 postoutburst). The ...
  • Excitation of Longitudinal Modes in Solar Magnetic Flux Tubes by p-Modes 
    Hasan, S. S; Kalkofen, W (Astronomical Society of the Pacific, 1998)
    This is a continuation of earlier work by Hasan (1997) on the interaction of longitudinal (sausage) waves in a slender flux tube with p-modes in the ambient medium. We use a realistic stratification for the flux tube and ...
  • Spectroscopic studies of R CrB during light minima - Absorption spectrum 
    Kameswara Rao, N; Giridhar, S; Ashoka, B. N (Royal Astronomical Society, 1990-05)
    R CrB was observed during the 1986 shallow minimum to study the spectral changes taking place during light minimum as compared with the spectrum at maximum light. The absorption spectrum at this minimum is very similar to ...
  • The giant branch of the Fornax dwarf spheroidal galaxy 
    Sagar, R; Hawkins, M. R. S; Cannon, R. D (The Royal Astronomical Society, 1990-01)
    A color-magnitude diagram for a large sample of stars in the Fornax dwarf spheroidal galaxy has been obtained from BV electronographic observations. These reach to the level of the horizontal branch, below V = 21 mag. The ...
  • Measurements of linear polarization of some Herbig Ae/Be stars 
    Jain, S. K; Bhatt, H. C; Sagar, R (The American Physical Society, 1990-05)
    The linear polarization of eight bright Herbig Ae/Be stars in UBVRI bands has been measured. No unique wavelength dependence of polarization magnitude or direction is found in these measurements. Comparison with earlier ...
  • High-resolution studies of forbidden O I and NH2 line emissions at 6300 A in Halley's comet 
    Prasad, C. D; Chandrasekhar, T; Desai, J. N; Ashok, N. M; Sivaraman, K. R; Rajmohan, R (Astronomical Society of the Pacific, 1988-06)
    The forbidden O I line and NH2 (0-8-0) emissions of Comet Halley at about 6300 A were observed during April 1986 using a Fabry-Perot spectrometer with a resolution of about 0.14 A. The forbidden O I line and NH2 rotational ...
  • On the Neutrino Emissivity of Degenerate Strange Quark Matter 
    Datta, B; Raha, S; Sinha, B (World Scientific Publishing Company, 1988-10)
    We examine the neutrino emissivity of a system of degenerate three-component (u, d, s) strange quark matter using improved expressions for the quark chemical potentials in a self-consistent manner, and obtain tighter bounds ...
  • Kinematical distances to open star clusters 
    Sagar, R; Bhatt, H. C (Indian Academy Sciences, 1988-06)
    Kinematical distances are estimated for six open star clusters. They agree fairly well with the photometric distances. The kinematical distances cannot, at present, be estimated better than the photometric distances. When ...
  • Equatorial electric-fields of ionospheric disturbance dynamo orgin 
    Sastri, J. H (European Geosciences Union, 1988-12)
    Persistent and significant reductions in the strength of the equatorial electrojet, accompanied by poor development of the equatorial ionization anomaly, are noted to sometimes occur in association with negative ionospheric ...
  • Filling factor determinations and their effects on planetary nebula studies 
    Mallik, D. C. V; Peimbert, M (Instituto de Astronomía, 1988-12)
    The authors have computed the filling factor for a sample of thirty-five galactic PN for which there are distance estimates independent of statistical arguments. They found that about half of the PN in their sample have ...
  • BV photometry of UX ARIETIS 
    Mohin, S; Raveendran, A. V (Indian Academy of Sciences, 1989-03)
    Differential BV photometry of UX Ari obtained on 58 nights during 1984-1985, 1985-1986, 1986-1987, and 1987-1988 observing season is presented. It is found that (B-V) is phase dependent, with the system being reddest at ...
  • Emission Spectrum of Hot R CrB star Mv Sgr 
    Kameswara Rao, N; Houziaux, L; Giridhar, S (Indian Academy Sciences, 1990-03)
    The new spectroscopic observation of MV Sgr obtained at ESO in 1987july shows enhanced emission lines of He I , λ 3889, [S II ] λ 4068 relative to the observations discussed by Jeffrey et al. (1988). The presence of [SII] ...

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