IIA Institutional Repository: Recent submissions

  • Emission-line spectra of XX Ophiuchi in 1996 and 1997 
    Goswami, A; Kameswara Rao, N; Lambert, D. L (The Observatory, 2001-04)
  • Chemical Compositions of Four Metal-poor Giant Stars 
    Giridhar, S; Lambert, D. L; Gonzalez, G; Pandey, G (University of Chicago Press, 2001-05)
    We present the chemical compositions of four K giants (CS 22877-1, CS 22166-16, CS 22169-35, and BS 16085-0050) that have [Fe/H] in the range -2.4 to -3.1. Metal-poor stars with [Fe/H]<-2.5 are known to exhibit considerable ...
  • Magnetic Activity and the Enhanced 5303 Ã Emission in Solar Active Regions 
    Ramesh, K. B; Nagabhushana, B. S; Varghese, B. A (Springer, 2001-03)
    Analysis of the intensity maps of Fexiv emission at λ=5303 Å obtained from the observations of ground-based coronagraphs during the sunspot minimum period 1985 and 1986 shows the persistent presence of localized strong ...
  • Possible Evidence of Long-Term Oscillations in the Solar Atmosphere 
    Raju, K. P; Singh, J; Srikanth, R; Chou, Dean-Yi; CA, TON team (Springer, 2001-03)
    We have obtained the temporal correlation function, Q(t), from time sequences of Caii K filtergrams and Dopplergrams from Antarctica, Taiwan Oscillation Network (TON) and Solar and Heliospheric Observatory (SOHO). Q(t) ...
  • Application of Non-linear Analysis to Intensity Oscillations of the Chromospheric Bright Points 
    Bhattacharya, J; Pereda, E; Kariyappa, R; Kanjilal, P. P (Springer, 2001-04)
    We have applied several nonlinear techniques to the intensity oscillations of the chromospheric bright points observed at the Vacuum Tower Telescope (VTT) of the Sacramento Peak Observatory. A 35-min time sequence obtained ...
  • Origin of the highest energy cosmic rays 
    Bhattacharjee, P (Indian Academy of Sciences, 1996-10)
    After briefly recalling the history of discovery of cosmic rays, the present statns of the subject is discussed. Cosmic-ray particles with energy exceeding 1020 eV have been detected. The origin of cosmic rays remains ...
  • Ambipolar diffusion in the solar atmosphere 
    Chitre, S. M; Krishan, V (Royal Astronomical Society, 2001-05)
    The process of non-linear ambipolar diffusion in the region overlying the solar surface can be an effective mechanism for producing sharp magnetic structures and current sheets. These may be the sites responsible for the ...
  • UV (IUE) spectra of the central stars of high latitude planetary nebulae Hb7 and Sp3 
    Gauba, G; Parthasarathy, M; Nakada, Y; Fujii, T (EDP Sciences, 2001-07)
    We present an analysis of the UV (IUE) spectra of the central stars of Hb7 and Sp3. Comparison with the IUE spectrum of the standard star HD 93205 leads to a spectral classification of O3V for these stars, with an effective ...
  • Temperature profiles of accretion discs around rapidly rotating strange stars in general relativity: A comparison with neutron stars 
    Bhattacharyya, S; Thampan, A. V; Bombaci, I (EDP Sciences, 2001-06)
    We compute the temperature profiles of accretion discs around rapidly rotating strange stars, using constant gravitational mass equilibrium sequences of these objects, considering the full effect of general relativity. ...
  • Infrared Space Observatory Spectra of R Coronae Borealis Stars. I. Emission Features in the Interval 3-25 Microns 
    Lambert, D. L; Kameswara Rao, N; Pandey, G; Ivans, I. I (American Astronomical Society, 2001-07)
    Infrared Space Observatory 3-25 μm spectra of the R Coronae Borealis stars V854 Cen, R CrB, and RY Sgr are presented and discussed. Sharp emission features coincident in wavelength with the well-known unidentified emission ...
  • Limits to the Mass and the Radius of the Compact Star in SAX J1808.4-3658 and Their Implications 
    Bhattacharyya, S (American Astronomical Society, 2001-06)
    We show that a survey of equations of state and observations of X-ray pulsations from SAX J1808.4-3658 give 2.27 Msolar as the upper limit of the compact star mass. The corresponding upper limit of the radius comes out to ...
  • Sunyaev-Zel'dovich distortion from early galactic winds 
    Majumdar, S; Nath, B. B; Chiba, M (Royal Astronomical Society, 2001-07)
    We consider the distortion in the cosmic microwave background (CMB) resulting from galactic winds at high redshift. Winds outflowing from galaxies have been hypothesized to be possible sources of metals in the intergalactic ...
  • First results from the Gauribidanur Radio heliograph 
    Subramanian, K. R; Ramesh, R; Sundararajan, M. S; Sastry, Ch. V (Kluwer Academic Publishers, 1996-03)
    Observations of the Sun at two frequencies (51 and 77 MHz) using the East-West arm of the Gauribidanur Radio heliograph are presented.
  • Particle Symmetries in Γ/M Ratios and the Lifetime of Proton 
    Sharma, A; Ramanna, R (World Scientific Publishing Company, 1996-09)
    In this letter it is shown that there is a close connection between the isospins of the fundamental particles and their masses and lifetimes. One of the important results is that the lifetime of the proton comes out to be ...
  • On the black hole trail: a personal journey 
    Vishveshwara, C. V (Indian academy of Sciences, 1996-12)
  • Probing the Evolution of the Gas Mass Fraction with the Sunyaev-Zeldovich Effect 
    Majumdar, S (American Astronomical Society, 2001-07)
    Study of the primary anisotropies of the cosmic microwave background (CMB) can be used to determine the cosmological parameters to a very high precision. The power spectrum of the secondary CMB anisotropies due to the ...
  • Modelling of a solar coronal loop 
    Krishan, V (Cambridge University Press, 1996-12)
    Montgomery and co-workers have developed a framework to describe the steady state of a turbulent magnetofluid, without the usual recourse to linearization. Thus the magnetic and velocity fields emerge in their fully nonlinear ...
  • Understanding the Radio Emission Geometry of PSR B0329+54 
    Gangadhara, R. T; Gupta, Y (American Astronomical Society, 2001-07)
    We have analyzed high-quality single-pulse data of PSR B0329+54 at 325 and 606 MHz to study the structure of the emission beam. Using the ``window-threshold technique,'' which is suitable for detecting weak emission ...
  • Abundance analyses of cool extreme helium stars 
    Pandey, G; Kameswara Rao, N; Lambert, D. L; Jeffery, C. S; Asplund, M (Royal Astronomical Society, 2001-07)
    Extreme helium stars (EHes) with effective temperatures from 8000 to 13000K are among the coolest EHes and overlap the hotter R CrB stars in effective temperature. The cool EHes may represent an evolutionary link between ...
  • Are radio pulsars strange stars? 
    Kapoor, R. C; Shukre, C. S (EDP Sciences, 2001-08)
    A remarkably precise observational relation for pulse core component widths of radio pulsars is used to derive stringent limits on pulsar radii, strongly indicating that pulsars are strange stars rather than neutron stars. ...

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