Surface brightness fluctuation distances to dwarf elliptical galaxies in the sculptor group

As part of an ongoing search for dwarf elliptical galaxies (dE's) in the vicinity of the Local Group (Jerjen et al.), we acquired deep B- and R-band images for five dE candidates identified on morphological criteria in the Sculptor (Scl) group legion. We carried out a surface brightness fluctuation (SBF) analysis on the R-band images to measure the apparent fluctuation magnitude (m) over bar(R) for each dE. Using predictions from stellar population synthesis models (Worthey) giving (M) over bar(R) values in the narrow range between -1.17 and -1.13, the galaxy distances were determined. All of these dE candidates turned out to be satellites of Scl group major members. A redshift measurement of the dE candidate ESO 294-010 yielded an independent confirmation of its group membership: the [O III] and H alpha emission lines from a small H II region gave a heliocentric velocity of 117 (+/-5) km s(-1), in close agreement with the velocity of its parent galaxy NGC 55 (upsilon. = 125 km s(-1)). The precision of the SBF distances (5%-10%) contributes to delineating the cigar-like distribution of the Sd group members, which extend over distances from 1.7 to 4.4 Mpc and are concentrated in three, possibly four subclumps. The Hubble diagram for nine Sd galaxies, including two of our dE's, exhibits a tight linear velocity-distance relation with a steep slope of 119 km s(-1) Mpc(-1). The results indicate that gravitational interaction among the Sd group members plays only a minor role in the dynamics of the group. However, the Hubble how of the entire system appears strongly disturbed by the large masses of our Galaxy and M31, which leads to the observed shearing motion. From the distances and velocities of 49 galaxies located in the Local Group and toward the Scl group, we illustrate the continuity of the galaxy distribution, which strongly supports the view that the two groups form a single supergalactic structure.