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Browsing by Subject "Line spectra"

Browsing by Subject "Line spectra"

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  • 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 ...
  • Abundance analysis of selected Cepheids and the galactic distribution of metallicity 
    Giridhar, S (Indian Academy of Sciences, 1983-06)
    The determinations are made in order to study the large-scale chemical inhomogeneities across the galactic disk. High-dispersion spectra are obtained of WZ Sgr, X Sgr, Zeta Gem, T Mon and SV Mon. The atmospheric abundances ...
  • BV photometry and H-alpha spectroscopy of the RS Canum Venaticorum binary V711 Tauri 
    Mohin, S; Raveendran, A. V (European Southern Observatory, 1993-08)
    Differential BV photometry of V711 Tau obtained on a total of 120 nights during the years 1984-1991 and H-alpha spectroscopy obtained on 14 nights during the 1990-1991 observing season are presented. We find that the mean ...
  • Chromospheric CA II K-line variations in the sun as a star over a solar cycle 
    Sivaraman, K. R; Singh, J; Bagare, S. P; Gupta, S. S (American Astronomical Society, 1987-02)
    The disk-averaged Ca II K profiles obtained at the Kodaikanal solar tower telescope for the period 1969-1984 are used to study the chromospheric variations in the sun as a star. The 1A index shows increases of 18 and 28 ...
  • CN 1-1 - A peculiar compact planetary nebula 
    Bhatt, H. C; Mallik, D. C. V (The European Southern Observatory, 1986-11)
    Cn 1-1 is an emission-line object that shows strong emission lines characteristic of high density planetary nebulae superposed on the stellar spectrum of an F5 III-IV star. The authors estimate the absolute luminosity of ...
  • Comparison of computed fluxes for Fe X and Fe XIV lines with observed values at 1980 eclipse 
    Raju, P. K; Singh, J (Kluwer Academic Publishers, 1987-09)
    Fluxes have been computed for Fex (6374 Å) and Fe xiv (5303 Å) lines as a function of solar radii and at various coronal tempratures. The electron density derived from the white light corona during the total solar eclipse ...
  • Detection of additional absorption in the post-outburst spectra of MU Centauri 
    Ghosh, K. K; Kuppuswamy, K; Pukalenthi, S; Selvakumar, G (The American Astronomical Society, 1991-09)
    A large number of photographic (92) and CCD (27) spectra of the pole-on Be star, Mu Cen, were obtained between February 1987 and May 1990. From the results of the above-mentioned spectra a weak outburst was detected in ...
  • The eccentric double-lined binary BD - 1 deg 1004 
    Kameswara Rao, N; Ashoka, B. N; Lloyd, C; Pike, C. D; Stickland, D. J (Indian Academy of Sciences, 1990-12)
    A new radial velocity study has been made of the highly eccentric, early-type binary BD - 1 deg 1004 using spectra from the Kavalur Observatory. All available archival material has also been reexamined. An attempt has been ...
  • Effects of aberration and advection on line formation 
    Peraiah, A (University of Chicago Press, 1991-10)
    The effects of inclusion of the aberration and advection terms in the equation of the line transfer are studied. Spherical shells whose ratios of outer (B) to inner (A) radii (B/A) are 2, 5, and 10 and with line-center ...
  • The effects of non-coherent electron scattering on spectral line formation 
    Rangarajan, K. E; Mohan Rao, D; Peraiah, A (Royal Astronomical Society, 1991-06)
    Spectral line profiles from a plane-parallel homogeneous atmosphere have been calculated for the complete and partial redistribution mechanisms (CRD and PRD) including coherent and noncoherent electron scattering. It is ...
  • Effects of rotation on the colours and line indices of stars. II - The effect on UVBY and H-beta indices 
    Mathew, A; Rajamohan, R (Indian Academy of Sciences, 1990-06)
    The intrinsic uvby and H-beta indices of member stars of Alpha-Persei, Pleiades, and Scorpio-Centaurus association have been analyzed in detail for rotation effects. These stars range in spectral type from B0 to F0 and the ...
  • Effects of stimulated emission on radiative transfer with partial redistribution 
    Rangarajan, K. E; Mohan Rao, D; Peraiah, A (The European Southern Observatory, 1990-08)
    The non-LTE line transfer with stimulated emission is studied. Stimulated emission is important for red transitions in hot stars and infrared transitions in cool stars. The deviation of the absorption and emission profiles ...
  • Emission-line CCD imaging of three southern symbiotic stars 
    Bhatt, H. C; Sagar, R (Indian Academy of Sciences, 1991-06)
    Symbiotic stars that are strong radio sources and have cool dust emitting in the IR are expected to have extended emission nebulae around them. In order to search for such emission nebulae, CCD imaging of three symbiotic ...
  • Equivalent widths of hydrogen Lyman alpha line in an expanding spherical atmosphere 
    Peraiah, A; Ingalgi, M. F (Indian Academy of Sciences, 1990-06)
    The profiles of hydrogen Lyman-alpha line in an expanding spherical atmosphere containing dust and gas were calculated. The variation of equivalent widths with velocities of expansion of the atmosphere, together with the ...
  • The He II line 4686 in WN binaries 
    Shylaja, B. S (Indian Academy of Sciences, 1987-06)
    The behaviour of the λ4686 line of He II in various WN binaries is studied for variations in total flux as well as radial velocities. It appears that the true motion of the WN component is not depicted by this line especially ...
  • The hot R Coronae Borealis star DY Centauri: Nebular and photospheric lines 
    Kameswara Rao, N; Giridhar, S; Lambert, D. L (The European Southern Observatory, 1993-12)
    High resolution spectra in the red region of the hot R CrB star DY Cen show the following characteristics: a strong absorption line spectrum dominated by lines of C II, N II, and Ne I inverse P-Cygni type profiles of some ...
  • An internally consistent set of oscillator strengths for Fe I lines 
    Giridhar, S; Ferro, A. A (Indian Academy of Sciences, 1989-03)
    An extensive set of internally consistent oscillator strength values for Fe I lines is compiled using literature data and scaling the oscillator strengths derived by different workers to that of Blackwell and his coworkers. ...
  • Is 21-cm absorption associated with the emission-line regions of quasars? 
    Krishan, V (Royal Astronomical Society, 1988-03)
    The 21-cm absorption line observed in several QSO systems is believed to originate in neutral hydrogen clouds in the vicinity of the QSOs. The aim of this paper is to show that 21-cm absorption can also originate in a ...
  • Kinematic studies of five galactic planetary nebulae 
    Banerjee, D. P. K; Anandarao, B. G; Jain, S. K; Mallik, D. C. V (The European Southern Observatory, 1990-12)
    High-resolution Fabry-Perot observations have been made to determine the velocity structure of five PNe and to subsequently relate the observations to the morphology of the objects. New kinematic data on one of these PNe, ...
  • On the coronal lines 5303 A and 6374 A 
    Peraiah, A; Varghese, B. A (Springer, 1989-06)
    Theoretical calculations of the observed coronal emission line profiles of Fe XIV (5303 A) and Fe X (6374 A) ions, which are observed at the time of total solar eclipse, are presented. Baumbach's relation of electron density ...

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