ATCA ⋆ H i Observations of the Peculiar Galaxy IC 2554

ATCA H i and radio continuum observations of the peculiar southern galaxy IC 2554 and its surroundings reveal typical signatures of an interacting galaxy group. We detected a large H i cloud between IC 2554 and the elliptical galaxy NGC 3136B. The gas dynamics in IC 2554 itself, which is sometimes described as a colliding pair, are surprisingly regular, whereas NGC 3136B was not detected. The H i cloud, which emerges from IC 2554 as a large arc-shaped plume, has a size of ∼ 30 kpc, larger than that of IC 2554. The total H i mass of the IC 2554 system is ∼ 2 × 10 M⊙, a third of which resides in the H i cloud. It is possible that tidal interaction between IC 2554 and NGC 3136B caused this spectacular H i cloud, but the possibility of IC 2554 being a merger remnant is also discussed. We also detected H i gas in the nearby galaxies ESO 092-G009 and RKK 1959 as well as an associated H i cloud, ATCA J1006–6710. Together they have an H i mass of ∼ 4.6× 10 M⊙. Another new H i source, ATCA J1007–6659, with an H i mass of only ∼ 2.2× 10 M⊙ was detected roughly between IC 2554 and ESO 092-G009 and corresponds to a face-on low surface brightness dwarf galaxy. Star formation is evident only in the galaxy IC 2554 with a rate of ∼4 M⊙ yr .