A detailed study of the ringed galaxy NGC 3344 ?

We study the relatively isolated galaxy NGC 3344, classified as SABbc, as part of our study of ringed isolated non-barred galaxies. This galaxy shows an inner and an outer ring, together with a small bar inside the inner ring. This bar is too small to relate it directly to the formation of the outer ring and we explore here its origin through HI (WSRT) line data together with broad band BR CCD-photometry and optical spectroscopy. We show that the bar is exponential and dominates the central parts, while the bulge component is small. This suggests a morphological type later than Sbc for NGC 3344, further supported by the strong abundance gradient reported in the literature for this galaxy. The inner ring defines the beginning of the spiral structure which partially wraps around this ring at small radii. Less than 1% of the HI is located in this ring which is mostly composed by a young stellar population. The outer ring shows colours similar to those of the inner ring, indicating that is actively forming stars. It is not located symmetrically with respect to the center of the galaxy, its center being shifted by about 18. Twenty percent of the HI emission is concentrated in this ring. The atomic gas is distributed asymmetrically in NGC 3344, extending 20% farther to the SE than in the opposite direction. The outer parts of the velocity field also deviate from that of a disk in circular rotation, with a pronounced warp especially abrupt to the SE. We derive a mass model for this galaxy, but the deviations from axisymmetry prohibit a good determination of a single pattern speed explaining the location of the rings.