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Browsing IIAP Publications by Subject "H alpha line"

Browsing IIAP Publications by Subject "H alpha line"

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  • 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 ...
  • CCD observations of the H-alpha line in late G and K supergiants and their interpretation 
    Mallik, S. G. V (American Astronomical Society, 1993-01-01)
    CCD echelle spectra of the H-alpha line at 6563 A have been obtained for a sample of 30 G and K supergiants with a spectral resolution of about 0.24 A. The data clearly indicate that the observed H-alpha profile is a deep ...
  • 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 ...
  • Effect of Lyman radiation transfer on the formation of the H-alpha line in supergiant chromospheres 
    Mallik, S. G. V; Mallik, D. C. V; Mohan Rao, D (European Southern Observatory, 1991-03)
    The paper pesents radiative transfer calculations of the H-alpha line in spherically expanding chromospheres of late-type supergiants where the assumption of radiative detailed balance in Lyman transitions has been relaxed. ...
  • Effects of magnetic shear, spot, and plage rotation on prominence evolution 
    Rausaria, R. R; Gupta, S. S; Selvendran, R; Raman, K. S; Singh, J (Kluwer Academic Publishers, 1993-08)
    We have studied the evolution of two dark H-alpha filaments as prominences during their disk passage from February 12 to February 19, 1992 and from March 6 to March 17, 1992, using Kodaikanal Observatory H-alpha and Ca II ...
  • 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 ...
  • Evolution of latitude zonal structure of the large-scale magnetic field in solar cycles 
    Makarov, V. I; Sivaraman, K. R (Springer, 1989-03)
    The latitude zonal component of the large-scale solar magnetic field is analyzed using H-alpha charts for the 1905-1982 period, and the poleward migration of prominences is used to calculate the time of reversal of the ...
  • Evolution of the optical spectrum of SN 1987a in the Large Magellanic Cloud 
    Ashoka, B. N; Anupama, G. C; Prabhu, T. P; Giridhar, S; Ghosh, K. K; Jain, S. K; Pati, A. K; Kameswara Rao, N (Indian Academy of Sciences, 1987-06)
    The evolution of the spectrum of SN 1987a is traced from 1987 February 26 to March 31. Based on the low-resolution spectroscopic data the authors identify the lines of H, He I, Na I, Fe II, Sc II, Ca II which are known to ...
  • Expanding chromospheres of late G and K supergiants 
    Mallik, S. G. V (Royal Astronomical Society, 1986-09)
    The radiative transfer problem in non-LTE moving atmospheres has been explicitly solved for Hα line profiles. These computations have been done for a schematic model of the line-forming region over a wide range of optical ...
  • Filament activity in a quiet region flare 
    Sundararaman, K; Gupta, S. S; Selvendran, R (Indian Academy of Sciences, 1993-03)
    We have taken the case of a circular H-alpha filament observed on May 9, 1979 erupting into a double-ribbon flare associated with a nonspot region. The plage motions are responsible for the filament reorientation and, here ...
  • 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 ...
  • Magnetic shear in flaring regions. I - Quantitative evaluation of the change in shear 
    Sivaraman, K. R; Rausaria, R. R; Aleem, S. M (Springer Netherlands, 1992-04)
    We have evaluated the shear angle of the neutral line of the non-potential magnetic field for one or two days prior to and after the flare event for 10 cases. We have used the Hagr filament positions to evaluate the shear ...
  • New results concerning the global solar cycle 
    Makarov, V. I; Sivaraman, K. R (Springer, 1989-09)
    The poleward migration-trajectory diagram of filament bands is derived for the years 1915-1982 from the H-alpha synoptic charts. The global solar activity commences soon after the polar-field reversal in the form of two ...
  • 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 ...
  • On the evaluation of magnetic shear from H-alpha pictures 
    Venkatakrishnan, P (Kluwer Academic Publishers, 1993-01-10)
    It is shown that pre-flare activity in H-alpha filaments is unrelated to changes in magnetic shear. Changes in the shear angle are found to be related to either redeployment of the sources of magnetic flux relative to the ...
  • Optical interferometric observations of a transient event of 1986 March 13 in the coma of Comet Halley 
    Prasad, D. C; Chandrasekhar, T; Desai, J. N; Ashok, N. M; Krishan, V (Indian Academy of Sciences, 1989-03)
    During the recent apparition of Comet Halley in 1985-86, a transient ionic event in the form of a blob of H2O(+) emission was recorded in the coma at about 0 h UT on March 13, 1986. Observations were carried out using a ...
  • Polarimetric observations of hydrogen deficient stars 
    Raveendran, A. V; Kameswara Rao, N; Deshpande, M. R; Joshi, U. C; Kulshrestha, A. K (Reidel Publishing Company, 1986)
    Polarimetric observations of HD 30353, SU Tau, XX Cam, R CrB, UV Cas, BD +13°3224, BD +10°2179 and HD 124448 are presented. The linear polarization of HD 30353 is found to vary appreciably at Hα over a time scale as short ...
  • Simultaneous infrared and H-alpha measurements of Be stars 
    Apparao, K. M. V; Tarafdar, S. P; Verma, R. P; Iyengar, K. V. K; Ghosh, K. K (Indian Academy of Sciences, 1993)
    The observed infrared excess in Be stars is usually interpreted as free-free and free-bound emission from a hot gas envelope around the Be star. This hot gas should also emit H-alpha line radiation. Earlier observations ...
  • Spectroscopic evolution of Nova LW Serpentis 1978 during its early decline 
    Prabhu, T. P; Anupama, G. C (Indian Academy of Sciences, 1987-12)
    Spectroscopic observations of Nova LW Serpentis have been obtained in 1978 during its decline from V of about 9.0 to V of about 10.2. It is found that the spectrum and its evolution compare well with those of a typical ...
  • Time-resolved spectral observations of spicule velocities at several heights 
    Hasan, S. S; Keil, S. L (American Astronomical Society, 1984-08)
    The vacuum telescope of the National Solar Observatory, Sacramento Peak was used to obtain H-alpha spectral observations of spicules. A set of spectra corresponding to five slit positions above the solar limb were recorded ...

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