Luminosity-line width relations and the extragalactic distance scale. I - Absolute calibration

Pierce, M.J. & Tully, R.B. 1992, Ap. J. 387, 47.

The study presents multicolor CCD photometry for a sample of 15 spiral and irregular members of the Local, Sculptor, and M81 groups with MB not greater than 16.0 and relevant as potential calibrators of the luminosity-line width relations. The sample contains those galaxies for which a ground-based study of Cepheid variables could provide accurate distances and hence an absolute calibration for the relations. Distance-independent relations involving line width, color, and mean surface brightness are discussed. These relations are used to examine the possibility of systematic differences between local galaxies employed to calibrate the relations and more distant samples. It is shown that, while the 'local calibrators' are indistinguishable from a large sample of field galaxies, they are bluer in the mean than a large sample of cluster galaxies. It is inferred that the primary source of uncertainty in the extragalactic distance scale lies within the Galactic calibration of the Cepheid and RR Lyrae variables.