High-latitude H I in the Low Surface Brightness Galaxy Ugc 7321

From the analysis of sensitive H i 21-cm line observations, we find evidence for vertically extended H i emission (|z| <∼2.4 kpc) in the edge-on, low surface brightness spiral galaxy UGC 7321. Three-dimensional modelling suggests that the H i disk of UGC 7321 is both warped and flared, but that neither effect can fully reproduce the spatial distribution and kinematics of the highest z-height gas. We are able to model the high-latitude emission as an additional H i component in the form of a “thick disk” or “halo” with a FWHM∼3.3 kpc. We find tentative evidence that the vertically extended gas declines in rotational velocity as a function of z, although we are unable to completely rule out models with constant V (z). In spite of the low star formation rate of UGC 7321, energy from supernovae may be sufficient to sustain this high-latitude gas. However, alternative origins for this material, such as slow, sustained infall, cannot yet be excluded. Subject headings: galaxies: ISM—galaxies: spiral—ISM: structure—galaxies: halos—galaxies: individual (UGC 7321)