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      Volume 30, Issue 3-4

      September 2009,   pages  133-210

    • Close Separation Triple System QSO 1009-0252 with Discordant Redshifts: Is the Spectrum of One Component Blueshifted?

      D. Basu

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      1009-0252 is a Quasi Stellar Object (QSO) with three components A, B, C. A, B are thought to be the result of gravitational lensing of one object, and A, C constitute a close pair with redshifts 2.74 and 1.62 respectively. Close separation pairs of QSOs with discordant redshifts have received special attention in recent years, probably because of the possibility that they may be physically associated, implying non-cosmological redshifts. Attempts have been made to explain their occurrences due to the effect of gravitational lensing. However, gravitational lensing has not offered a completely satisfactory explanation for this triplet. Furthermore, examination revealed some inadequacies and inconsistencies in the redshift identification of the observed lines in the component A. Observational results of 1009-0252 therefore remain puzzling.We propose an alternative explanation by suggesting that A, B actually constitute a close pair and C is an unrelated object in the field. We show that the observed spectrum of A can be interpreted as blueshifted. This implies that A, B are two separate objects, one (A) approaching us and the other (B) receding from us, and are not the result of gravitational lensing of a single object. The oppositely directed pair A, B may have been ejected due to the merger of two galaxies.

    • A Method for Judging Decay or Growth of the Magnetic Field of Pulsar

      Lin-Sen Li

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      This paper provides a method for judging growth or decay of the magnetic field of pulsar by using pulse period 𝑃, or frequency 𝑣, and its first and second derivatives $\dot{P}$, $\ddot{P}$ or $\dot{v}$, $\ddot{v}$. The author uses this method to judge the growth or decay of the magnetic field of Crab pulsar. The judged result for Crab pulsar is that the magnetic field of Crab pulsar is growing now, but it is not decaying. The result corresponds with the actual case of Crab pulsar.

    • Velocity Curve Studies of Spectroscopic Binary Stars V380 Cygni, V401 Cyg, V523 Cas, V373 Cas and V2388 Oph

      K. Karami R. Mohebi

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      Using measured radial velocity data of five double lined spectroscopic binary systems V380 Cygni, V401 Cyg, V523 Cas, V373 Cas and V2388 Oph, we find corresponding orbital and spectroscopic elements via the method introduced by Karami & Mohebi (2007) and Karami & Teimoorinia (2007). Our numerical results are in good agreement with those obtained by others using more traditional methods.

    • Rapid Neutron Capture Process in Supernovae and Chemical Element Formation

      Rulee Baruah Kalpana Duorah H. L. Duorah

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      The rapid neutron capture process (r-process) is one of the major nucleosynthesis processes responsible for the synthesis of heavy nuclei beyond iron. Isotopes beyond Fe are most exclusively formed in neutron capture processes and more heavier ones are produced by the r-process. Approximately half of the heavy elements with mass number 𝐴 ≻ 70 and all of the actinides in the solar system are believed to have been produced in the r-process. We have studied the r-process in supernovae for the production of heavy elements beyond 𝐴 = 40 with the newest mass values available. The supernova envelopes at a temperature ≻ 109 K and neutron density of 1024 cm-3 are considered to be one of the most potential sites for the r-process. The primary goal of the r-process calculations is to fit the global abundance curve for solar system r-process isotopes by varying time dependent parameters such as temperature and neutron density. This method aims at comparing the calculated abundances of the stable isotopes with observation.We have studied the r-process path corresponding to temperatures ranging from 1.0 × 109 K to 3.0 × 109 K and neutron density ranging from 1020 cm-3 to 1030 cm-3. With temperature and density conditions of 3.0 × 109 K and 1020 cm-3 a nucleus of mass 273 was theoretically found corresponding to atomic number 115. The elements obtained along the r-process path are compared with the observed data at all the above temperature and density range.

    • On Out of Plane Equilibrium Points in Photo-Gravitational Restricted Three-Body Problem

      M. K. Das Pankaj Narang S. Mahajan M. Yuasa

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      We have investigated the out of plane equilibrium points of a passive micron size particle and their stability in the field of radiating binary stellar systems Krüger-60, RW-Monocerotis within the framework of photo-gravitational circular restricted three-body problem. We find that the out of plane equilibrium points (𝐿𝑖, 𝑖 = 6, 7, 8, 9) may exist for range of 𝛽1 (ratio of radiation to gravitational force of the massive component) values for these binary systems in the presence of Poynting–Robertson drag (hereafter PR-drag). In the absence of PR-drag, we find that the motion of a particle near the equilibrium points 𝐿6,7 is stable in both the binary systems for a specific range of 𝛽1 values. The PR-drag is shown to cause instability of the various out of plane equilibrium points in these binary systems.

    • Analytical Treatment of the Two-Body Problem with Slowly Varying Mass

      W. A. Rahoma F. A. Abd El-Salam M. K. Ahmed

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      The present work is concerned with the two-body problem with varying mass in case of isotropic mass loss from both components of the binary systems. The law of mass variation used gives rise to a perturbed Keplerian problem depending on two small parameters. The problem is treated analytically in the Hamiltonian frame-work and the equations of motion are integrated using the Lie series developed and applied, separately by Delva (1984) and Hanslmeier (1984). A second order theory of the two bodies eject mass is constructed, returning the terms of the rate of change of mass up to second order in the small parameters of the problem.

    • Author Index

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    • Subject Index

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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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