An HI study of three long-tailed irregular galaxies in the cluster Abell 1367

Ananda Hota1,2,3 *, D.J. Saikia2
1 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617,
Taiwan, Republic of China,
2 National Centre for Radio Astrophysics (TIFR), Ganeshkhind, Pune 411 007, India
3 JAP Program, Indian Institute of Science, Bangalore 560 012, India

Abstract. We present the results on the distribution and kinematics of Hi gas with higher sensitivity and in one case of higher spectral resolution as well than reported earlier, of three irregular galaxies CGCG 097073, 097079 and 097087 (UGC 06697) in the cluster Abell 1367. These galaxies are known to exhibit long (50-75 kpc) tails of radio continuum and optical emission lines (H) pointing away from the cluster centre and arcs of starformation on the opposite sides of the tails. These features as well as the Hi properties, with two of the galaxies (CGCG 097073 and 097079) exhibiting sharper gradients in Hi intensity on the side of the tails, are consistent with the Hi gas being affected by the ram pressure of the intracluster medium. However the Hi emission in all the three galaxies extends to much smaller distances than the radio-continuum and H tails, and are possibly still bound to the parent galaxies. Approximately 20-30 per cent of the Hi mass is seen to accumulate on the downstream side due to the effects of ram pressure.

Keywords: galaxies: individual: CGCG 097073, CGCG 097079 and CGCG 097087 (UGC 06697) - galaxies: interaction - galaxies: ISM - galaxies: kinematics and dynamics

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