| Abstract | We present new ion{H}{1} images of the dust-lane elliptical galaxy NGC 5266 already known from single-dish observations to contain a large amount of ion{H}{1}. Our new data confirm that NGC 5266 contains ~2.4 x 10(10) msun (for Hdeg = 50 kmsMp) of neutral hydrogen, i.e. more than most spiral galaxies of similar luminosity. The gas extends to ~8(') each side of the nucleus, or 8 times the optical half-light radius R_e. Surprisingly, most of the ion{H}{1} extends almost orthogonal to the optical dust lane. A small fraction of the ion{H}{1} is associated with the dust lane and there are some hints of a faint warp connecting the two structures. The ion{H}{1} distribution is somewhat clumpy and asymmetric, but the overall velocity field in the inner 4(') can be successfully modeled by assuming that the gas lies mainly in two perpendicular planes - in the plane of the dust lane in the central parts and orthogonal to this in the outer regions. Beyond the 4(') radius, the gas has a different structure and may be in two tidal tails, or an edge-on ring. Measurement of the ion{H}{1} rotation curve is affected by asymmetries in the gas distribution, but the rotation velocity is at least 250 kms at a radius of 4(') , and a flat rotation curve of ~270 kms is consistent with the data. This would imply a value of M / L_B ~8 at ~4 R_e. If the outermost ion{H}{1} is in an edge-on ring, we estimate M / L_B ~16 at ~8 R_e. Comparing this with the value derived from optical observations for the inner region we find an increase of M / L_B by a factor ~2.7 at r ~4 R_e, and by 5.3 at r ~8 R_e. The large amount of neutral gas observed in NGC 5266 (M_HI/L_B ~0.2) and the ion{H}{1} morphology, suggest that this object may have formed from the merger of two spiral galaxies. If so, NGC 5266 probably represents a relatively old merger remnant since most of the ion{H}{1} gas appears settled. |
