Ω_bar in NGC 5597 from Very Large Array H i 21 cm Observations

Abstract We report Very Large Array B-configuration observations of the atomic hydrogen 21 cm line emission from the barred disk galaxy NGC 5597 at an angular resolution of ∼ 7.″1 × 4.″2. Using the resonance method, and assuming the ratio of the corotation radius to the semimajor axis of the stellar bar is unity (  ≡ R CR / a bar = 1 ), we estimate the angular pattern speed of the stellar bar to be, Ωbar ∼ 15.3 km s−1 kpc−1. This constant value for Ωbar crosses Ωgas + κ(R)/4 at a distance ∼6.73 kpc, which would correspond to the spatial location of the north spiral structure near an outer m = 4 resonance. This value of Ωbar is similar to the values estimated for other bright nearby barred galaxies that exhibit circumnuclear rings (near inner Lindblad resonance) or outer rings (near outer Lindblad resonance).