ATCA HI observations of the peculiar galaxy IC 2554

Abstract

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 × 109 M⊙, one‐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 and an associated H i cloud, ATCA J1006–6710. Together they have an H i mass of ∼4.6 × 108 M⊙. Another new H i source, ATCA J1007–6659, with an H i mass of only ∼2.2 × 107 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−1.

H i debris in the IC 1459 galaxy group

“…Many detailed H i studies, ranging from galaxies in close pairs (e.g., Gordon et al 2001;Koribalski & Dickey 2004;Koribalski & López-Sánchez 2009;Sengupta et al 2015), compact groups Koribalski et al 2003;Serra et al 2012), Hickson compact groups (Hickson 1982;Verdes-Montenegro et al 2001), loose groups (Kilborn et al 2009;Pisano et al 2011) and clusters (Chung et al 2009) have been carried out. The stripped gas may be found as tidal tails, filaments, and plumes near the interacting galaxies, e.g.…”

“…The stripped gas may be found as tidal tails, filaments, and plumes near the interacting galaxies, e.g. in the Abell 1367 cluster (Scott et al 2010) and nearby groups (e.g., Higdon 1996;Koribalski et al 2003;Koribalski & Dickey 2004;English et al 2010). These extended H i structures can be difficult to detect, requiring high sensitivity single-dish observations to measure the low-surface brightness emission and long interferometric observations with emphasis on short baselines such as not to resolve out the diffuse H i emission.…”

Massive star formation in Wolf-Rayet galaxies

“…Neutral hydrogen gas is the best tracer of galaxy-galaxy interactions because the H i distribution is usually several times larger than the optical extent, hence more easily disrupted by external forces (tidal interactions, gas infall, ram pressure stripping) than the stellar disk (Broeils & van Woerden 1994;Salpeter & Hoffman 1996). The distribution and kinematics of atomic gas within galaxies is usually more or less regular, but in many cases they revealed complex entities between galaxies such as tails, ripples, bridges, arcs, or independent H i clumps that, in many cases, show little disturbance in their corresponding optical images (e.g., Schneider et al 1989;Yun et al 1994;Hibbard & van Gorkom 1996;Verdes-Montenegro et al 2001, 2002Putman et al 2003;Koribalski et al 2003Koribalski et al , 2005Temporin et al 2003Temporin et al , 2005Emonts et al 2006;Ekta et al 2008;English et al 2010; see also…”

A Gaseous Group with Unusual Remote Star Formation

“…There are now a number of sensitive, high resolution HI observations that have detected nearby gas-rich groups and/or HI dwarf companions. For example, a comparison system is IC 2554 which has a HI mass of 3.2 Â 10 10 M } and is part of a compact gas-rich group of galaxies (Koribalski et al 2003). Another comparison system is that of NGC 2903 which has two gaseous dwarf galaxies nearby with HI masses between 10 6 -10 7 M } (Irwin et al 2009).…”