IIAP Publications: Recent submissions

  • V, I CCD photometry of metal-rich bulge globular clusters: NGC 6553 
    Sagar, R; Subramaniam, A; Richtler, T; Grebel, E. K (The European Southern Observatory, 1999-03)
    We have carried out VI CCD photometry of about 40 000 stars down to V ~ 23 mag in an area of about 6' x 10' centered on the metal-rich Galactic bulge globular cluster NGC 6553 and an adjacent field region. Our photometry ...
  • Late-type giants with infrared excess. I. Lithium abundances 
    Jasniewicz, G; Parthasarathy, M; de Laverny, P; Thévenin, F (European Southern Observatory, 1999-02)
    de la Reza et al. (1997) suggested that all K giants become Li-rich for a short time. During this period the giants are associated with an expanding thin circumstellar shell supposedly triggered by an abrupt internal mixing ...
  • Steady and fluctuating parts of sun's internal magnetic field 
    Gokhale, M. H; Hiremath, K. M (International Astronomical Union, 1993-01)
    We have modeled the 'steady' part of sun's internal poloidal magnetic field in the form of a central dipole and a central hexapole with strengths (0.6 +/- 0.1)B(o)R(0) exp 3 and (0.16 +/- 0.05)B(o)R(0) exp 5 embedded in ...
  • A seismic model of the solar convective envelope 
    Shibahashi, H; Hiremath, K. M; Takata, M (International Astronomical Union, 1998)
    We deduce the density, pressure, and temperature profiles in the solar convective envelope by solving the basic equations for mass conservation and the hydrostatic equilibrium with the imposition of the helioseismologically ...
  • Dynamical phenomena in sunspots. I. Time dependent relaxation to equilibrium 
    Gangadhara, R. T; Hasan, S. S (European Southern Observatory, 1997-11)
    We have adapted a general purpose time-dependent 2-D code to study dynamical phenomena in sunspots. In the first part of our investigation, we numerically simulate the dynamical relaxation to equilibrium of a sunspot. ...
  • Determination of the atmospheric point spread function by a parameter search 
    Krishnakumar, V; Venkatakrishnan, P (European Southern Observatory, 1997-12)
    The result of blind deconvolution is a reconstructed image that has non positive intensities. The number of these non positive pixels has been used as an estimator for the departure from a perfect reconstruction. Simulations ...
  • The chemical composition of IRAS 05341+0852: a post-AGB F supergiant with 21 MU M emission 
    Reddy, B. E; Parthasarathy, M; Gonzalez, G; Bakker, E. J (European Southern Observatory, 1997-12)
    An abundance analysis of the photosphere of the F-type Post-AGB candidate IRAS 05341+0852 is presented. The analysis of the spectra suggests that the atmospheric model: Teff=6500 K, log g=0.5, xi_ {t}=5 km s(-1) and ...
  • Post-Maximum Optical and Infrared Observations of Nova V1425 Aquilae 1995 
    Kamath, U. S; Anupama, G. C; Ashok, N. M; Chandrasekhar, T (American Astronomical Society, 1997-12)
    We present the post-maximum optical spectroscopy and infrared photometry of Nova V1425 Aquilae 1995. The data indicate that the nova belongs to the Fe ii class and that it formed an optically thin dust shell at a very early ...
  • Active Galactic Nuclei and Galaxy Formation 
    Chokshi, A (The American Astronomical Society, 1997-12)
    It is proposed that early jet-induced activity around active galactic nuclei (AGNs) is responsible for triggering large-scale star formation in protogalaxies and results in the formation of giant ellipticals and spheroids ...
  • Weak emission line [WELS] central stars of planetary nebulae are [WC]-PG1159 stars 
    Parthasarathy, M; Acker, A; Stenholm, B (European Southern Observatory, 1998-01)
    The characteristics of the spectra of weak emission line stars (WELS) are found to be very similar to that of [WC]-PG1159 and PG1159 objects. On the basis of the spectra we find 31 WELS central stars of planetary nebulae ...
  • FG Sagittae: A Newborn R Coronae Borealis Star? 
    Gonzalez, G; Lambert, D. L; Wallerstein, G; Kameswara Rao, N; Smith, V. V; McCarthy, J. K (The American Astronomical Society, 1998-01)
    We have monitored FG Sge's spectroscopic changes since the time just prior to its dramatic fading in 1992 August. The most significant qualitative changes in the spectrum include large variations in the strength of the C2 ...
  • VI CCD photometry of metal-rich globular clusters: NGC 6528 
    Richtler, T; Grebel, E. K; Subramaniam, A; Sagar, R (European Southern Observatory, 1998-01)
    We present CCD photometry in V and I for the metal-rich globular cluster NGC 6528. A comparison with previous photometry reveals discrepancies of the order 0.1 to 0.2 mag in V, emphasizing the need for independent photometry. ...
  • Charged particle trajectories in a toroidal magnetic and rotation-induced electric field around a black hole 
    Sengupta, S (World Scientific Publishing Company, 1997-10)
    Trajectories of charged particles in a combined poloidal, toroidal magnetic field and a rotation-induced unipolar electric field superposed on a Schwarzschild background geometry have been investigated extensively in the ...
  • Application of the effective valence shell Hamiltonian method to accurate estimation of oscillator strengths and excitation energies of Mg-like ions 
    Chaudhuri, R. K; Das, B. P; Freed, K. F (American Institute of Physics, 1998-02)
    The ab initio effective valence shell Hamiltonian (Hυ) method is used to compute the excitation energies and oscillator strengths for resonance transitions in Mg-like ions, as well as their lowest ionization potentials. ...
  • On the line ratio diagnostics for NeV, MgV, SiVII and Mg VII solar ions 
    Dwivedi, B. N; Mohan, Anita; Raju, P. K (Elsevier, 1997)
    We present NeV/MgV and MgVII/SiVII theoretical line intensity ratios as a function of electron density and temperature for physical conditions within the solar chromosphere-corona transition region. The electron pressure ...
  • Short-Term Optical Variability in Broad Absorption Line QSOs 
    Anupama, G. C; Chokshi, A (The American Astronomical Society, 1998-02)
    We present the first results from a pilot program to monitor the short-term optical variability in broad absorption line system QSOs. Intranight optical variations of 5% were detected on timescales of 1 hr in QSOs 0846+156 ...
  • On the development of abnormally large postsunset upward drift of equatorial F region under quiet geomagnetic conditions 
    Sastri, J. H (American Geophysical Union, 1998-03)
    The regular postsunset enhancement of upward drift of the equatorial F region is observed to be abnormally large on certain quiet days (Ap ≤ 5) as manifested by an anomalous dusktime increase of F region height. We explored ...
  • The Puppis OB III association: polarization measurements 
    Bhatt, H. C; Jain, S. K; Sagar, R (European Southern Observatory, 1998-03)
    Optical linear polarization measurements of association members and field stars in the region of the Puppis OB III association are presented. The association members are found to have larger values of polarization than the ...
  • Correlations of Faint Galaxies: A Monte Carlo Approach 
    Chokshi, A (The American Astronomical Society, 1998-03)
    Monte Carlo methods are employed to study the angular correlations arising from simulated galaxy clusters in flux-limited samples. In particular, we show that the models of Chokshi and coworkers that best reproduce the ...
  • Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XII. Ground-based Monitoring of 3C 390.3 
    Dietrich, M; Peterson, B. M; Albrecht, P; Altmann, M; Barth, A. J; Bennie, P. J; Bertram, R.; Bochkarev, N. G; Bock, H; Braun, J. M; Burenkov, A; Collier, S; Fang, L. Z; Francis, O. P; Filippenko, A. V; Foltz, C. B; Gaessler, W; Gaskell, C. M; Geffert, M; Ghosh, K. K; Hilditch, R. W; Honeycutt, R. K; Horne, K; Huchra, J. P; Kaspi, S; Kuemmel, M; Leighly, K. M; Leonard, D. C; Malkov, Yu. F; Mikhailov, V; Miller, H. R; Morrill, A. C; Noble, J; O'Brien, P. T; Oswalt, T. D; Pebley, S. P; Pfeiffer, M; Pronik, V. I; Qian, B. C; Robertson, J. W; Robinson, A.; Rumstay, K. S; Schmoll, J; Sergeev, S. G; Sergeeva, E. A; Shapovalova, A. I; Skillman, D. R; Snedden, S. A; Soundararajaperumal, S; Stirpe, G. M; Tao, J; Turner, G. W; Wagner, R. M; Wagner, S. J; Wei, J. Y; Wu, H.; Zheng, W; Zou, Z. L (The American Astronomical Society, 1998-04)
    Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-1995 are presented. The broadband fluxes (B, V, R, and I), the spectrophotometric optical continuum flux F lambda (5177 A), and the integrated ...

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