The H${miny I}$ Content of the Eridanus Group of Galaxies

[摘要] The H${miny I}$ content of galaxies in the Eridanus group is studied using the GMRT observations and the HIPASS data. A significant H${miny I}$ deficiency up to a factor of 2–3 is observed in galaxies in the high galaxy density regions. The H${miny I}$ 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 H${miny I}$ 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 H${miny I}$ deficiency in clusters could have originated in groups. The co-existence of S0s and severely H${miny I}$ deficient galaxies in the Eridanus group suggests that tidal interaction is likely to be an effective mechanism for transforming spirals to S0s.

[学科分类] 天文学(综合)

[关键词] Galaxy: evolution;galaxies: groups;clusters;individual: Eridanus;radio lines: H${miny I}$ 21cm-line.