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      https://www.ias.ac.in/article/fulltext/joaa/027/04/0411-0423

    • Keywords

       

      Stars: binaries: eclipsing; stars: pulsars: individual:4U 1538-52; X-rays: stars

    • Abstract

       

      We report here results from detailed timing and spectral studies of the high mass X-ray binary pulsar 4U 1538-52 over several binary periods using observations made with the Rossi X-ray Timing Explorer (RXTE) and BeppoSAX satellites. Pulse timing analysis with the 2003 RXTE data over two binary orbits confirms an eccentric orbit of the system. Combining the orbitial parameters determined from this observation with the earlier measurements we did not find any evidence of orbital decay in this X-ray binary. We have carried out orbital phase resolved spectroscopy to measure changes in the spectral parameters with orbital phase, particularly the absorption column density and the iron line flux. The RXTE-PCA spectra in the 3–20 keV energy range were fitted ∼6.4 keV, whereas the BeppoSAX spectra needed only a power law and Gaussian emission line at ∼6.4 keV in the restricted energy range of 0.3–10.0 keV. An absorption along the line of sight was included for both the RXTE and BeppoSAX data. The variation of the free spectral parameters over the binary orbit was investigated and we found that the variation of the column density of absorbing material in the line of sight with orbital phase is in reasonable agreement with a simple model of a spherically symmetric stellar wind from the companion star.

    • Author Affiliations

       

      U. Mukherjee1 H. Raichur1 2 B. Paul1 S. Naik3 N. Bhatt4

      1. Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai - 400 005, India
      2. Joint Astronomy Program, Indian Institute of Science, Bangalore - 560 012, India
      3. Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa - 229 8510, Japan
      4. Nuclear Research Laboratory, Bhabha Atomic Research Centre, Mumbai - 400 085, India
    • Dates

       
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