Velocity fields in the southern barred spirals NGC 613, 1097, 1313 and 1365

The velocity fields of NGC 613, 1097, 1313 and 1365 have been investigated by means of a total of 17 long-slit spectrograms. The nuclei of NGC 613 and NGC 1097 were found to be rotating faster than the underlying bars, confirming and extending earlier work by Burbidge et al. (1964) and by Burbidge & Burbidge (1960). Lindblad's observations of the nucleus of NGC 1365, combined with measurements of the outer points described here suggest that a similar situation occurs in this galaxy. These observations imply that bars are primarily density wave features. Mass estimates for the nuclei of NGC 613 and 1097 are |6× 10⁹ M_| (⁠|r< 0.7| kpc) and |7× 10⁹ M_| (⁠|r< 0.3| kpc) respectively. Unless NGC 1365 is the most massive spiral known, there is likely to be gas flow along the arms at |~ 40-60 s⁻¹|⁠. The velocity field of NGC 1313 is not consistent with any combination of rotation and expansion. Rotation of the apparent major axis by more than 90° may indicate distortion due to a companion galaxy. The bar probably has a mass |~ 7× 10⁸ M_|⁠.