Journal of Astrophysics and Astronomy

, Volume 22, Issue 1, pp 35–50

GMRT observations of interstellar clouds in the 21cm line of atomic hydrogen

  • Rekhesh Mohan
  • K. S. Dwarakanath
  • G. Srinivasan
  • Jayaram N. Chengalur
Article

DOI: 10.1007/BF02933589

Cite this article as:
Mohan, R., Dwarakanath, K.S., Srinivasan, G. et al. J Astrophys Astron (2001) 22: 35. doi:10.1007/BF02933589

Abstract

Nearby interstellar clouds with high (|ν|≥10km s−1) random velocities although easily detected in NaI and CaII lines have hitherto not been detected (in emission or absorption) in the HI 21cm line. We describe here deep Giant Metrewave Radio Telescope (GMRT) HI absorption observations toward radio sources with small angular separation from bright O and B stars whose spectra reveal the presence of intervening high random velocity CaII absorbing clouds. In 5 out of the 14 directions searched we detect HI 21cm absorption features from these clouds. The mean optical depth of these detections is ∼0.09 and FWHM is ∼10km s−1, consistent with absorption arising from CNM clouds.

Key words

ISM: clouds, kinematics and dynamics Radio lines: ISM 

Copyright information

© Indian Academy of Sciences 2001

Authors and Affiliations

  • Rekhesh Mohan
    • 1
  • K. S. Dwarakanath
    • 1
  • G. Srinivasan
    • 1
  • Jayaram N. Chengalur
    • 2
  1. 1.Raman Research InstituteBangaloreIndia
  2. 2.National Center for Radio AstrophysicsPuneIndia

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