Journal of Astrophysics and Astronomy

, Volume 26, Issue 1, pp 71–87

TheHI content of the Eridanus group of galaxies

  • A. Omar
  • K. S. Dwarakanath

DOI: 10.1007/BF02702452

Cite this article as:
Omar, A. & Dwarakanath, K.S. J Astrophys Astron (2005) 26: 71. doi:10.1007/BF02702452


The HI content of galaxies in the Eridanus group is studied using the GMRT observations and the HIPASS data. A significant HI deficiency up to a factor of 2–3 is observed in galaxies in the high galaxy density regions. The HI deficiency in galaxies is observed to be directly correlated to the local projected galaxy density, and inversely correlated to the line-of-sight radial velocity. Furthermore, galaxies with larger optical diameters are predominantly in the lower galaxy density regions. It is suggested that the HI deficiency in Eridanus is due to tidal interactions. In some galaxies, evidences of tidal interactions are seen. An important implication is that significant evolution of galaxies can take place in the group environment. In the hierarchical way of formation of clusters via mergers of groups, a fraction of the observed HI deficiency in clusters could have originated in groups. The co-existence of S0s and severely HI deficient galaxies in the Eridanus group suggests that tidal interaction is likely to be an effective mechanism for transforming spirals to S0s.

Key words

Galaxy: evolution galaxies: groups, clusters individual: Eridanus radio lines:HI 21cm-line 

Copyright information

© Indian Academy of Sciences 2005

Authors and Affiliations

  • A. Omar
    • 1
  • K. S. Dwarakanath
    • 1
  1. 1.Raman Research InstituteBangaloreIndia
  2. 2.ARIESNainital, 263 129, UttaranchalIndia

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