H-I STUDIES OF THE SCULPTOR GROUP GALAXIES .4. NGC-247

A study of the H I properties and mass distribution of the Sculptor group galaxy NGC 247, from VLA* observations, is presented. The H I disk turns out to be fairly small with a diameter comparable to the optical. The total H I mass is 8.0×108 script M sign⊙. From the velocity field, a systemic velocity Vsys = 161 km s-1, an inclination i = 74°, and a position angle P.A. = 170° are found. The derived rotation curve is not flat, but rising out to the last observed point. Differences of ≃20 km s-1 are seen between both sides (approaching and receding) of the galaxy. A study of the mass distribution suggests a (script M sign/LB)* = 4.0 for the stellar disk. For the dark halo, the best-fit model gives rc = 24.2 kpc and ρ0, = 0.0046 script M sign⊙ pc-3. While the (script M sign/MB)* is well defined, the halo parameters are not well constrained. At the last point of rotation curve, (script M sign/LB)global ≃ 11.