Warp or Lag? The Ionized and Neutral Hydrogen Gas in the Edge-on Dwarf Galaxy UGC 1281

The properties of gas in the halos of galaxies tell us something about the properties of the interstellar medium. Here we report on deep HI and H alpha observations of UGC 1281 in order to determine the existence of extra planar gas and its kinematics. This is the first time the halo characteristics of a dwarf galaxy have been investigated. These observations are compared to 3D models in order to determine the distribution of HI in the galaxy. We find that UGC 1281 has H alpha emission up to 25 ''(655 pc,similar to 0.6 H alpha h(R)) in projection above the plane and in general a low H. flux. Its HI extends 70 ''(1.8 kpc, similar to 1.5 HI h(R)) in projection from the plane. This neutral extra-planar gas can be explained by either a line-of-sight warp or a thick disk with rotational velocities that decline with a vertical gradient of 10.6 +/- 3.7 km s(-1) kpc(-1). The line-of-sight warp model is the preferred model as it is conceptually simpler. In either model the warp starts well within the optical radius.