H i in NGC 5433 and its environment: high‐latitude emission in a small galaxy group

We present H  i synthesis maps of the edge‐on starburst NGC 5433 and its environment, obtained with the Very Large Array in its C and D configurations. The observations and spectral model residuals of the main disc emission in NGC 5433 reveal three extraplanar features. We associate two of these features with coherent extraplanar extensions across multiple spectral channels in our data, including a complete loop in position–velocity space. Interpreting the latter as an expanding shell we derive a corresponding input energy of 2 × 10 54 erg , comparable to that for the largest supershells found in the Galaxy and those in other edge‐on systems. NGC 5433 is in a richer environment than previously thought. We confirm that KUG 1359+326 is a physical companion to NGC 5433 and find two new faint companions, both with Minnesota Automated Plate Scanner identifications, which we label SIS‐1 and SIS‐2. Including the more distant IC 4357, NGC 5433 is the dominant member of a group of at least five galaxies, spanning over 750 kpc in a filamentary structure. A variety of evidence suggests that interactions are occurring in this group. While a number of underlying mechanisms are consistent with the morphology of the high‐latitude features in NGC 5433, we argue that environmental effects may play a role in their generation.