GMRT H I observations of the Eridanus group of galaxies

Abstract

TThe GMRT H I 21cm-line observations of galaxies in the Eri- danus group are presented. The Eridanus group, at a distance of ∼ 23 Mpc, is a loose group of ∼ 200 galaxies. The group extends to more than 10 Mpc in projection. The velocity dispersion of the galaxies in the group is ∼ 240 km s−¹ . The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E + S0) and 70% (Sp + Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for ∼ 200 h. H I emission was detected from 31 galaxies. The channel rms of ∼ 1 mJy beam−¹ was achieved for most of the image-cubes made with 4 h of data. The corresponding H I column density sensitivity (3σ ) is ∼ 1 × 10²⁰ cm−² for a velocity-width of ∼ 13.4 km s−¹ . The 3σ detection limit of H I mass is ∼ 1.2 × 10⁷ M☉ for a line-width of 50 km s− ¹ . Total H I images, H I velocity fields, global H I line profiles, H I mass surface densities, H I disk parameters and H I rotation curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies. These data will be used to study the H I and the radio con- tinuum properties, the Tully–Fisher relations, the dark matter halos, and the kinematical and H I lopsidedness in galaxies.