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[138.12] Planetary Nebula Based Distances to M83 and NGC 5068

K. A. Herrmann, R. Ciardullo, M. Vinciguerra (Penn State)

M83, the Southern Pinwheel Galaxy, is one of the largest galaxies of the nearby M83/NGC 5128 galaxy group. The distances to individual members of the group are somewhat controversial: Planetary Nebula Luminosity Function (PNLF), Surface Brightness Function (SBF), and Tip of the Red Giant Branch (TRGB) measurements yield values anywhere from 3.1 Mpc to 5.1 Mpc, and the measurements seem to suggest a sizable separation between the largest galaxies of the group. The only reliable Cepheid distance in the group is to NGC 5253 (4.1 ±0.1 Mpc); a ground-based Cepheid measurement to M83 (4.5 ±0.3 Mpc) is based on only 12 objects and may be affected by problems with crowding and blending.

We will be presenting the results of a wide-field [O III] \lambda5007 and H\alpha survey for planetary nebulae (PNe) in two galaxies of the group: M83 and NGC 5068. In all, we detected ~300 PN candidates in M83 and ~ 60 in NGC~5068. Using these data and the PNLF method, we derive the distances which we will compare to other PNLF distances to group members. After we obtain radial velocities for the PNe, we will ultimately use the vertical velocity dispersion, \sigma_z, to determine the mass surface density and mass-to-light ratios throughout the galaxies' disks.

This work is supported by NSF grant AST 00-71238.

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.