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    • Fulltext

       

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/007/03/0141-0153

    • Keywords

       

      galactic centre; recombination lines—Galaxy; 3 kpc arm-interstellar medium; distributed ionized gas

    • Abstract

       

      Observations of the H272α recombination line towards the galactic centre show features near VLSR= 0, −50 and + 36 kms−1. We have combined the parameters of these features with the available H166α measurements to obtain the properties of the ionized gas present along the line of sight and also in the ‘3 kpc arm’. For the line-of-sight ionized gas we get an electron density around 7 cm−3 and a pathlength through it ∼ 10–60 pc. The emission measure and the electron temperature are in the range 500–2900 pc cm−6 and 2000–6000 K. respectively. The ionized gas in the 3 kpc arm has an electron density of 30 cm−3 and extends over 9 pc along the line of sight if we assume an electron temperature of 104 K. Using the available upper limit to the intensity of the H351α recombination line, we show that the distributed ionized gas responsible for the dispersion of pulsar signals should have a temperature >4500 K. and a minimum filling factor of 20 per cent. We also show that recombination lines from the ‘warm ionized’ gas proposed by McKee & Ostriker (1977) should be detectable in the frequency range 100–150 MHz towards the galactic centre with the sensitivity available at present.

    • Author Affiliations

       

      K. R. Anantharamaiah1 2 D. Bhattacharya3

      1. Rahman Research Institute, Bangalore - 560080
      2. National Radio Astronomy Observatory, VLA, P. O. Box 0, Socorro, New Mexico - 87801, USA
      3. Joint Astronomy Program, Department of Physics, Indian Institute of Science, Bangalore - 560012

    • Dates

       
      Published
      September 1986
      Manuscript received
      7 March 1986
      Accepted
      24 April 1986

  • 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.

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