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Browsing by Subject "H alpha line"

Browsing by Subject "H alpha line"

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  • 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 ...
  • 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 ...
  • The variation of photospheric active regions in HD 127535 
    Mekkaden, M. V; Geyer, E. H (European Southern Observatory, 1988-04)
    UBVRI photometry of the chromospherically active star HD 127535 obtained during April 1987 is presented. The analysis shows that the light variation is quasi-sinusoidal and the amplitude and the phase of the light minimum ...
  • VLA observations of solar active regions at 6 and 20 CM 
    Alissandrakis, C. E; Kundu, M. R; Shevgaonkar, R. K (The European Southern Observatory, 1991-11)
    High-resolution observations are presented of two active regions at 6 and 20 cm over a period of 5 days, together with H-alpha and photospheric magnetic fields. The large-scale emission at 20 cm is associated with the ...

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