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Browsing by Subject "Stellar spectra"

Browsing by Subject "Stellar spectra"

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  • 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 ...
  • 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 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 ...
  • 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 far-infrared (IRAS) excess in BQ() and related stars 
    Parthasarathy, M; Pottasch, S. R (European Southern Observatory, 1989-11)
    The FIR IRAS flux distributions and color of 12 peculiar emission-line objects (HD 51585, Hen 401, Hen 591, Hen 1013, He 2-138, M 2-9, HD 326971, Hen 1357, Hen 1428, Tc 1, Hen 1475, and M 1-26) are found to be similar to ...
  • Fibre spectroscopy and BV CCD photometry of the southern open cluster NGC 3114 
    Sagar, R; Sharples, Ray M (European Southern Observatory, 1991-04)
    New spectroscopic and photometric observations are presented for a sample of faint stars which extends the color-magnitude diagram of the open cluster NGC 3114 down to V = 16 mag. The distance to the cluster is estimated ...
  • H-alpha variability in the quiescent spectrum of the recurrent nova T Coronae Borealis 
    Anupama, G. C; Prabhu, T. P (Blackwell Publishing, 1991-12)
    The emission lines in the quiescent spectrum of the recurrent nova T Coronae Borealis are variable. Optical spectra recorded during the years 1985-90 show one full cycle of high and low states. After removing the slow ...
  • 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 hydrogen-deficient irregular variable star V348 SGR 
    Kameswara Rao, N; Nandy, K (1984-07)
    The distribution of the reddening material around V 348 Sgr was studied using the IUE low resolution spectra. The nebula surrounding the star has a reddening of E(B-V) = 0.3 caused mainly by the foreground interstellar ...
  • Large dust grains in the dark cloud B5 
    Bhatt, H. C (Royal Astronomical Society, 1986-09)
    Polarization measurements of stars in the region of the dark cloud B5 indicate that the average dust grain size in the cloud is much larger than the mean interstellar grain size. Within the cloud, the average grain size ...
  • A new discussion on the M(v) - W(O I 7774 A) relationship for F-G stars in the light of high-resolution data 
    Arellano Ferro, A; Giridhar, S; Goswami, A (Royal Astronomical Society, 1991-05)
    High-resolution CCD data and a large group of F-G stars of fundamentally determined distances are used here to investigate the intrinsic nature of the M(v) - W(O I) relation and the effect of other atmospheric parameters ...
  • On the absolute magnitude of V482 Cygni, an R Coronae Borealis star 
    Kameswara Rao, N; Lambert, D. L (Astronomical Society of the Pacific, 1993-06)
    An identification of V482 Cygni, a R Coronae Borealis star, with a quadruple system containing a K5 III star is rejected. High-resolution spectra show that the radial velocity of V482 Cyg and the K5 III star differ by 35 ...
  • Polarization of resonance lines formed in extended spherical atmospheres 
    Nagendra, K. N (Kluwer Academic Publishers, 1989-04)
    The present consideration of the polarization problem posed by resonance lines in extended spherical atmospheres assumes that the atmosphere in question is at rest and emphasizes the determination of constraints that can ...
  • Radiative transfer with Compton scattering in plane parallel geometry 
    Peraiah, A (Indian Academy of Sciences, 1990-06)
    The equation of radiative transfer with Compton scattering is solved. The specific intensity has been expanded by Taylor series with respect to wavelength and the first three terms have been retained in solving the transfer ...
  • Radiative transfer with Compton scattering in spherically symmetric shells 
    Peraiah, A; Varghese, B. A (Astronomical Society of Japan, 1990)
    The radiative transfer equation with Compton scattering is solved for spherically symmetric shells. The purpose of the study is to determine how gamma rays or X-rays change their energies and how they become reflected 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 ...
  • Spectroscopic studies of the southern Cepheid β Dor 
    Giridhar, S (Universidad Nacional Autonoma De Mexico, 1987-05)
    Fine analysis of the southern Cepheid β Dor has been conducted at different phases with the aim to derive atmospheric parameters at those phases. Atmospheric abundances have been derived for Fe group elements and s-process ...
  • The ultraviolet spectrum of the hydrogen-poor binary HD 30353 
    Parthasarathy, M; Hack, M; Tektunali, G (The European Southern Observatory, 1990-04)
    An analysis is made of the high- and low-resolution UV spectra of the hydrogen-poor star HD 30353. The stellar wind profiles of the resonance lines of N V, C V, and Si IV are found to be similar to those observed in Upsilon ...

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