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    • Electron Temperatures in W51 Complex from High Resolution, Low Frequency Radio Observations

      P. K. Srivastava A. Pramesh Rao

      Volume 31 Issue 1 March 2010 pp 43-58

    • Fulltext

       

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/031/01/0043-0058

    • Keywords

       

      ISM; HII regions; radio continuum; individual (W51).

    • Abstract

       

      W51 is a giant radio complex lying along the tangent to the Sagitarius arm at a distance of about 7 kpc from the Sun, with an extension of about 1° in the sky. It is divided into three components A, B, C where W51A and W51B consist of many compact HII regions while W51C is a supernova remnant. We have made continuum radio observations of these HII regions of the W51 complex at 240, 610, 1060 and 1400 MHz using GMRT with lower resolution (20'' × 15'') at the lowest frequency. The observed spectra of the prominent thermal subcomponents of W51 have been fitted to a free-free emission spectrum and their physical properties like electron temperatures and emission measures have been estimated. The electron temperatures from continuum spectra are found to be lower than the temperatures reported from radio recombination line (RRL) studies of these HII regions indicating the need for a filling factor even at this resolution. Also, the observed brightness at 240 MHz is found to be higher than expected from the best fits suggesting the need for a multicomponent model for the region.

    • Author Affiliations

       

      P. K. Srivastava1 A. Pramesh Rao2

      1. Dayanand Anglo-Vedic College, Civil Lines, Kanpur 208 001, India.
      2. National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune University Campus, Post Bag 3, Ganeshkhind P.O., Pune 411 007, India.

    • Dates

       
      Published
      March 2010
      Manuscript received
      8 June 2007
      Accepted
      5 February 2010

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