• Volume 5, Issue 2

      June 1984,   pages  99-185

    • On gamma radiation from the magellanic clouds and galactic supernova remnants — Possible antiproton sources in the galaxy

      V. L. Ginzburg V. S. Ptuskin

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      Radiation from the Magellanic Clouds is discussed from the point of view of near future possibilities in observational γ-ray astronomy. The γ-ray fluxes expected according to the metagalactic and galactic theories of the origin of cosmic rays are compared. It is shown that the strongest test of the metagalactic hypothesis will be provided by a determination of the ratio of γ-ray fluxes from SMC and LMC. The γ-ray luminosity of a typical young supernova remnant that can generate sufficient antiprotons is estimated. It is shown that such remnants must have a short phase during which they are very powerful γ-ray emitters.

    • Spatial interferometry in the mid-infrared region

      C. H. Townes

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      The potential of high-resolution spatial interferometry for detailed mapping and precision astrometry in the mid-infrared region, somewhat analogous to interferometry now done in the microwave region, is discussed from an instrumental point of view. Some results from a prototype system and from tests of atmospheric properties are given. The design of a more advanced two-telescope system now under construction is outlined. This involves movable telescopes of 1.65 m aperture and of high precision, using heterodyne detection of infrared in the 10 Μm atmospheric window.

    • Spectra of the ammonium radical: the schüler bands

      G. Herzberg

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      The main bands of the Schüler system of ND4 and NH4 have been observed at high resolution. On the basis of these spectra, Watson, in a separate paper, has analysed the ND4 main band showing that it represents a2F22 A1 transition of a tetrahedral molecule. The observed wavenumber data for both ND4 and NH4 are presented; the latter have not yet been analysed. Isotopic bands for15ND4,14ND3H,14ND2H2,14NDH3 have also been obtained and as previously pointed out confirm the assumed carrier of the spectrum. The much weaker bands accompanying the main Schüler band on the short and long wavelength sides are photographed at medium resolution. The interpretation of these bands in terms of the vibrational levels of upper and lower states is briefly discussed.

    • The Ooty synthesis radio telescope: First results

      G. Swarup

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      A 4-km synthesis radio telescope has recently been commissioned at Ootacamund, India for operation at 327 MHz. It consists of the Ooty Radio Telescope (530 m × 30 m) and 7 small antennas which are distributed over an area of about 4 km × 2 km. It has a coverage of about ± 40‡ in declination δ. The beam-width is about 40 arcsec × 90 arcsec at δ = 0‡ and about 40 arcsec × 50 arcsec at δ = 40‡. The sensitivity attained for a 5:1 signal-to-noise ratio is about 15 m Jy after a 10-hour integration.

      The observational programmes undertaken and some of the results obtained recently are summarized. The radio halo around the edge-on spiral NGC 4631 is found to have a larger scale-height at 327 MHz than is known at higher frequencies. Mapping of interesting radio galaxies at 327 MHz is being carried out; preliminary results for 0511-305 (∼2 Mpc) and 1333-337 (∼750 kpc) are summarized. The very-steep-spectrum radio source in the Abell cluster A85 is found to be resolved; since it has no obvious optical counterpart, it is conceivable that it is a remnant of past activity of a galaxy that has drifted away in about 109 years.

    • Brightness, polarization and electron density of the solar corona of 1980 february 16

      K. R. Sivaraman M. Jayachandran K. K. Scaria G. S. D. Babu S. P. Bagare A. P. Jayarajan

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      During the eclipse of 1980 February 16 we photographed the solar corona at an effective wavelength of 6300 å. Using a quadruple camera we also obtained the coronal pictures in polarized light for four Polaroid orientations. We have used these observations to derive the coronal brightness and polarization and from these the electron densities in the corona out to a distance of about 2.5 R⊙ from the centre of the disc. The coronal brightness matches well with that of the corona of 1958 October 12.

    • Spot activity in the RS CVn binary UX arietis

      M. B. K. Sarma B. V. N. S. Prakasa Rao

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      Photoelectric observations of the RS CVn type non-eclipsing binary UX Arietis obtained at Nizamiah Observatory during the observing seasons of 1975–76, 1981–82 and 1982–83 are presented. The light curve of UX Ari showed a distortion wave with an amplitude inV varying from 0.02 mag during 1975–76 to 0.15 mag during 1982–83. An analysis of the available data shows that the light maximum is almost constant. It is also evident that the light-curve minimum decreases as the wave amplitude increases. The constant light at maximum,V = 6.51 ± 0.03 indicates the unspotted photospheric brightness. It is also suggested that the variation in meanV brightness is mainly due to spot activity and not due to intrinsic variation.

    • Effects of partial frequency redistribution functions RII, RIII and RV on source functions

      D. Mohan Rao K. E. Rangarajan A. Peraiah

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      The effects of partial frequency redistribution on the formation of spectral lines have been studied. We considered the angle-averaged RII, RIII andRv types of redistribution with isotropic phase function, Transfer equation with plane-parallel geometry is solved in isothermal atmospheres. For an atmosphere with constant thermal sources, the frequency-dependent source function SL (Rv) lies below SL (RIII) but above SL(RIII) in the line wings.

    • Spectroscopic binaries near the north galactic pole - Paper 10: HR 4668

      R. F. Griffin

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      Photoelectric radial-velocity measurements confirm and refine the preliminary orbit derived for HR 4668 by Christie on the basis of eight Lick spectrograms taken more than 50 years ago.

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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