IIA Institutional Repository: Recent submissions

  • Spatial Distribution of Stellar Mass in the Large Magellanic Cloud Star Clusters 
    Subramaniam, A; Sagar, R; Bhatt, H. C (European Southern Observatory, 1993-06)
    The stellar mass distributions have been studied in halo regions (radius ranging from ~19 to 94 arcsec) of 5 young Large Magellanic Cloud star clusters. Effects of mass segregation have been observed in only NGC 1711. A ...
  • The variation of filament direction in a flaring region 
    Rausaria, R. R; Raman, K. S; Aleem, P. S. M; Singh, J (Kluwer Academic Publishers, 1993-07)
    We have analyzed the variations in shear angle over a time interval of 30 s during a flare on June 11, 1991, using Kodaikanal Observatory spectroheliogram and photoheliogram data, and assuming H-alpha filaments are a proxy ...
  • Measurement of Kodaikanal white-light images. I - A comparison of 35 years of Kodaikanal and Mount Wilson sunspot data 
    Sivaraman, K. R; Gupta, S. S; Howard, R. F (Kluwer Academic Publishers, 1993-07)
    Areas and positions of individual sunspot umbrae measured in white-light solar images from Kodaikanal and Mount Wilson are compared and shown to be in quite good agreement. The agreement is sufficiently good that it is ...
  • A search for intra-night optical variability in radio-quiet QSOs 
    Gopal-Krishna; Sagar, R; Witta, P. J (Royal Astronomical Society, 1993-06-15)
    We report results from a new program, using the 2.34-m Vainu Bappu Telescope, to search for intra-night optical variability in five QSOs which are radio-quiet but optically bright and luminous. Our limited data show mild ...
  • X-Ray Spectral Variability of the Seyfert Galaxy NGC4593 
    Ghosh, K. K; Soundararajaperumal, S (European Southern Observatory, 1993-06)
    X-ray (0.1-10 keV) spectra of NGC 4593 were obtained with EXOSAT on seven epochs between 1984 and 1986 using the low and medium energy detectors. Detailed results of the spectral analysis of the seven spectra (obtained ...
  • The combined effect of partial redistribution and non-coherent electron scattering on polarized resonance line transfer 
    Nagendra, K. N; Rangarajan, K. E; Mohan Rao, D (Royal Astronomical Society, 1993-06-15)
    The combined effect of partial frequency redistribution by atoms (PRD) and noncoherent electron scattering (NCES) on line formation is studied, taking account of the polarization state of the radiation field in resonance ...
  • Orbital decay of protostellar binaries in molecular clouds 
    Gorti, U; Bhatt, H. C (Royal Astronomical Society, 1996-11)
    The evolution of protostellar binary system is investigated while it is embedded in its parent molecular cloud core and is acted upon by gas drag as a result of dynamical friction. Approximate analytical results are obtained ...
  • Green's matrix for Compton reflection of polarized radiation from cold matter 
    Poutanen, J; Nagendra, K. N; Svensson, R (Royal Astronomical Society, 1996-12)
    The Compton-reflected spectrum from cold matter for incident X-rays and gamma-rays with arbitrary angular, spectral and polarization properties can be determined by a simple folding of Green's matrix with the incident ...
  • Information flow due to controlled interference in entangled systems 
    Srikanth, R (Indian Academy of Sciences, 2002-08)
    We point out that controlled quantum interference corresponds to measurement in an incomplete basis and implies a nonlocal transfer of classical information. A test of whether such a generalized measurement is permissible ...
  • Spin squeezing and quantum correlations 
    Mallesh, K. S; Sirsi, S; Sbaih, M. A. A; Deepak, P. N; Ramachandran, G (Indian Academy of Sciences, 2002-08)
    We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented ...
  • Proof of absence of spooky action at a distance in quantum correlations 
    Unnikrishnan, C. S (Indian Academy of Sciences, 2002-08)
    I prove that there is no spooky action at a distance and nonlocal state-reduction during measurements on quantum entangled systems. The prediction of quantum theory as well as experimental results are in conflict with the ...
  • Evidence for the quantum birth of our Universe 
    Unnikrishnan, C. S; Gillies, G. T; Ritter, R. C (Indian Academy of Sciences, 2002-08)
    We present evidence for a nonsingular origin of the Universe with initial conditions determined by quantum physics and relativistic gravity. In particular, we establish that the present temperature of the microwave background ...
  • High Resolution Spectroscopy of QY Sge 
    Kameswara Rao, N; Goswami, A; Lambert, D. L (Astronomical Society of India, 2002-09)
    High resolution spectral analysis of QY Sge, a post AGB star is presented here. The spectrum of QY Sge is characterized by three major components: absorption lines representative of a G supergiant, sharp emission lines ...
  • Deconstructing IRAS 07027-7934 
    Surendiranath, R (EDP Sciences, 2002-08)
    The planetary nebula IRAS 07027-7934 has a compact ionized core surrounded by a large cloud of matter believed to be of neutral gas and dust particles. A photoionization model of this ionized core is presented in this ...
  • The local stellar population of nova regions in the Large Magellanic Cloud 
    Subramaniam, A; Anupama, G. C (EDP Sciences, 2002-08)
    This study aims at identifying and understanding the parent population of novae in the Large Magellanic Cloud (LMC) by studying the local, projected, stellar population. The star formation history of the local environment ...
  • Modern optical astronomy: technology and impact of interferometry 
    Saha, S. K (The American Physical Society, 2002-04)
    The present ``state of the art'' and the path to future progress in high-spatial-resolution imaging interferometry is reviewed. The review begins with a treatment of the fundamentals of stellar optical interferometry, the ...
  • Constraints on stellar grain formation from presolar graphite in the murchison meteorite 
    Bernatowicz, T. J; Cowsik, R; Gibbons, P. C; Lodders, K; Fegley, B. Jr; Amari, S; Lewis, R. S (American Astronomical Society, 1996-12)
    We report the results of isotopic, chemical, structural, and crystallographic microanalyses of graphitic spherules (0.3-9 μm) extracted from the Murchison meteorite. The spherules have sup12C/sup13C ratios ranging over 3 ...
  • Radiative transfer in the distorted and irradiated atmospheres of close binary components 
    Peraiah, A; Srinivasa Rao, M (EDP Sciences, 2002-07)
    We studied the transfer of line radiation in the distorted and expanding atmospheres of close binary components. We assumed that the distortion of the atmosphere is caused by self rotation and tidal force exerted by the ...
  • Photometric study of two W UMa-type systems in the intermediate age open cluster Be 33 
    Rukmini, J; Rao, P. V (Astronomical Society of India, 2002-09)
    Study of eclipsing binaries in open clusters offers information regarding the age of the cluster in addition to the properties of the component stars. In this paper we present the analysis of two W UMa systems discovered ...
  • Term values of Na-like iron group highly stripped ions using coupled-cluster theory 
    Ray, H (Institute of Physics, 2002-07)
    More accurate term values, a few line strengths and transition probabilities for the E2 transitions of the iron group highly stripped ions Fe XVI, Co XVII and Ni XVIII are reported. We have used the fully relativistic ...

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