• Volume 9, Issue 2

      June 1988,   pages  67-125

    • On the scalar-tensor theory of Lau and Prokhovnik

      S. D. Maharaj A. Beesham

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      Recently Lau & Prokhovnik (1986) have formulated a new scalar-tensor theory of gravitation which reconciles Dirac’s large numbers hypothesis with Einstein’s theory of general relativity. The present work points out an error in the time-dependent cosmological term and the scalar potential given by Lau and Prokhovnik. The correct forms for these quantities are derived. Further, a vacuum Robertson-Walker solution to the generalized field equations is obtained, under an anasatz that we propose, which illustrates that the theory is, in some sense, incomplete.

    • Spectroscopic binaries near the North Galactic Pole paper 14: HD 118234

      R. F. Griffin

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      Photoelectric radial-velocity measurements show that the Seventh-magnitude star HD 118234 is a spectroscopic binary in a very eccentric 59-day orbit.

    • Global properties of star formation in spiral galaxies

      T. N. Rengarajan K. V. K. Iyengar

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      Samples of spiral galaxies from two catalogues of 21 cm line observations and a catalogue of near-infrared observations of nearby galaxies have been used in conjunction with Infrared Astronomical Satellite data to study correlations involving MG, the dynamic mass of the galaxies, the luminosities in theH band (1.6Μm), the blue band and the far infrared bands and the mass of atomic hydrogen, it is found that both the blue and the far-IR luminosities which are indicators of star formation averaged over ∼3 × l09 and ∼107 years respectively, have a linear dependence onMG On the other hand, theH luminosity which is a measure of star formation averaged over the lifetime of galaxies, has a steeper power law dependence onMG. The correlations observed do not have significant dependence on the morophological type of the galaxies There is a poor correlation between the far-infrared luminosity and the mass of atomic hydrogen. The mass of atomic hydrogen has a dependence of the formMG. Because of the decrease in the mean mass for later morphological types and due to differences in power law dependences of luminosities in different bands onMG, the mean value of luminosity-to-mass ratio is a constant for blue and far-IR bands, decreases for theH band and the gas-to-mass ratio increases as morphological type increases.

    • Spectroscopic observations of SN1987a in the LMC

      J. B. Hearnshaw V. J. McIntyre A. C. Gilmore

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      This paper describes the results of optical spectroscopy of SN1987a carried out at Mt John University Observatory on a regular basis since 1987 February 25. Typical spectra are presented in an evolutionary sequence, and velocities of Balmer and selected metallic lines are measured in either emission or absorption. The velocities are interpreted together with the results of photoelectric photometry. The Barnes-Evans relationship has been applied to the photometry to give an angular diameter of the photosphere. The expansion velocity of the photosphere is initially about 3700 km s-1 which is similar to the asymptotic value from weaker absorption lines such as the MgIb line. After 40 days the photosphere appears to expand more slowly and it reaches a maximum size of about 145 A.U. after about 100 days before receding inwards. The photometry and spectroscopy together result in a distance modulus of 18.3 ± 0.2.

    • Effects of rotation on the colours and line indices of stars 1. The alpha Persei cluster

      R. Rajamohan Annamma Mathew

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      Analysis of the available observational data for the α-Persei cluster members shows that rotation effects on the intermediate-band indices c1 and (u-b) are considerable. In c1, rotation produces a reddening of 0.040 magnitudes per 100 km s-1 In (u-b) the effect for B stars is found to be 0.06 magnitudes per 100 km s-1 ofV sin i.

      The binaries and peculiar stars are found to behave differently in the colour excess (due to rotation) versusV sin i diagrams. These empirical effects can be utilised to recalibrate these colour indices and also to separate members that are either chemically peculiar or in binary systems.

    • Kinematical distances to open star clusters

      Ram Sagar Harish C. Bhatt

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      Kinematical distances are estimated for six open star clusters. They agree fairly well with the photometric distances. The kinematical distances cannot, at present, be estimated better than the photometric distances. When more accurate proper motion measurements become available the kinematical distances will improve considerably and may then be used to calibrate the cosmic distance scale.

    • Corrigenda

      A. B. Delone E. A. Makarova G. V. Yakunina

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  • 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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