Volume 4, Issue 3
September 1983, pages 161-224
pp 161-169 September 1983
The eclipsing binary UV Piscium was observed with the standardUBV filters during 1976-77, 1977-78 and 1978-79 observing seasons with the 1.22-m reflecting telescope of the Japal-Rangapur Observatory. A wave-like distortion on the light curve noticed by Carr (1969), Oliver (1974), Sadik (1979) and Zeiliket al. (1982a) is confirmed by the present observations. Combining our observations with those of Carr, Oliver and Sadik, it is found that the distortion wave is moving towards decreasing orbital phase with a period of about 1200 days. The source of the observed distortion wave is found to be the hotter component.
pp 171-173 September 1983
Photoelectric radial-velocity measurements show that HD 116378 is a spectroscopic binary with a period of 17.76 days. The visual companion star is not physically related to it.
pp 175-182 September 1983
The law of limb darkening has been calculated when the atmosphere of the primary component is illuminated by the extended surface of the secondary component in a binary system. The specific intensities calculated at infinity show marked changes when the plane-parallel approximation is replaced by the assumption of spherical symmetry. The middle portions of the illuminated surface reflect maximum radiation while the innermost and outermost layers show lesser amount of reflected radiation.
pp 183-189 September 1983
The effects of reflection on the formation of spectral lines is investigated. We have assumed a purely scattering atmosphere and studied how the equivalent widths change due to irradiation from the secondary. Generally, the flux in the lines is increased at all frequency points, the cores of the lines receiving more flux than the wings. Moreover, the proximity of the secondary component changes the equivalent widths considerably. The further away the secondary is from the primary the higher are the equivalent widths.
pp 191-196 September 1983
We show that inverse Compton losses of ultrarelativistic electrons travelling upstream through the outflowing fields of a radio pulsar prevent the entry ofall cosmic ray electrons into most pulsars’ magnetospheres. We also argue that gamma ray triggering is probably not relevant, and conclude that the external triggering of electron-positron cascades proposed by Ruderman & Sutherland and by Radhakrishnan is not likely to be a major contributor to the plasma dynamics of pulsars.
pp 197-204 September 1983
The relative abundances of the nuclei from neon to iron in the energy interval 150–400 MeV/n have been estimated by using a balloon borne cellulose-nitrate plastic detector. The source abundances are obtained by extrapolating the near-earth abundances using leaky box model of cosmic ray propagation in the interstellar space. The results are compared with those of other investigators and a general agreement is obtained. However, a discrepancy arises especially in the case of Al which is not detected in the present investigation.
pp 205-213 September 1983
A sample of 92 galaxies with published surface photometric data inB band and inclined randomly to the line of sight is selected and used to compute the photometric parameterQN. The dependence ofQN on the apparent flatteningq is found and discussed for different morphological groups.QN is more sensitive toq in earlier-type galaxies.
pp 215-224 September 1983
The observations of intensity reductions or absorption bursts in the solar decametric radio-continuum are reported. The reductions are interpreted as the absorption of continuum radiation by a shock-generated ion-sound turbulence present in the layer above the continuum level. The duration of the absorption is attributed to the lifetime of the ion-sound turbulence while the depth of absorption is determined by the level of Langmuir waves generated as a result of absorption.
Volume 40 | Issue 2
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