2011MNRAS.414.3444K

The properties of gas in the haloes of galaxies constrain global models of the interstellar medium. Kinematical information is of particular interest since it is a clue to the origin of the gas. Until now mostly massive galaxies have been investigated for their halo properties.

Here we report on deep H I and Hα observations of the edge-on dwarf galaxy UGC 1281 in order to determine the existence of extraplanar gas and the kinematics of this galaxy. This is the first time a dwarf galaxy is investigated for its gaseous halo characteristics. We have obtained Hα integral field spectroscopy using PPAK at Calar Alto and deep H I observations with the Westerbork Synthesis Radio Telescope (WSRT) of this edge-on dwarf galaxy. These observations are compared to 3D models in order to determine the distribution of H I in the galaxy.

We find that UGC 1281 has Hα emission up to 25 arcsec (655 pc) in projection above the plane and in general a low Hα flux. Compared to other dwarf galaxies UGC 1281 is a normal dwarf galaxy with a slowly rising rotation curve that flattens off at 60 km/s and a central depression in its H I distribution. Its H I extends 70 arcsec (1.8 kpc) in projection from the plane. This gas can be explained by either a warp partially in the line-of-sight or a purely edge-on warp with rotational velocities that decline with a vertical gradient of 10.6 ±3.7 km/s/kpc. 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.