The velocity field of the barred spiral galaxy NGC 5383

The velocity field of the barred spiral galaxy NGC 5383 has large-scale deviations from the pattern expected for only circular motions. Velocity gradients across the nucleus show a simple sinusoidal dependence on position angle, but the interpretation in terms of rotational and radial motions is dependent upon the adopted geometry of the galaxy. Exterior to the nucleus, the kinematics are more complex and are discussed in terms of two models. A likely model is that of a warped disk, which could be the result of a recent gravitational interaction with a nearby dwarf-barred spiral companion. For a warped-disk model, only rotational velocities are present in the nucleus. A second model interprets the observed velocities in terms of a rotating planar disk, in which case outward radial motions of approx. 180 km s/sup -1/ exist in the bar. Nuclear gas is both rotating and contracting (V/R = 136 +- 10 km s/sup -1/, E(R) = -60 +- 10 km s/sup 1/ at R = 800 pc). Observation of the integrated 21 cm neutral hydrogen emission shows an asymmetrical profile, with the maximum flux occurring at the systemic velocity of the companion. The asymmetry may be due to 21 cm radiation from hydrogen in the companion, to a nonuniform distribution of neutral hydrogen in NGC 5383, or to both. The total 21 cm integrated flux density, 16.7 Jy km s/sup -1/, corresponds to a total hydrogen mass of 9 x 10/sup 9/ Msub solar, and a M/sub HI//L/sub opt/ of 0.2 at an adopted distance of 50 Mpc. A comparison with the barred spiral NGC 3351 shows NGC 5383 to be more luminous and bluer, and to have a higher hydrogen mass and higher angular momentum. 9 figures, 3 tables.