Context. Star clusters and emission-line nebulae are valuable probes of stellar populations and the chemical evolution of nearby galaxies. NGC 7793, the flocculent spiral in the Sculptor Group, contains a rich population of clusters and nebulae, although only a few absorption line objects have been studied spectroscopically so far. Aims. Our goal is to confirm the membership of a selected sample of cluster and nebula candidates in NGC 7793 and to derive their main physical and chemical properties. Methods. Candidates for globular clusters and planetary nebulae were selected using images from the Hubble Space Telescope (HST). Their structural and photometric parameters were determined. These candidates were then observed spectroscopically with Gemini–GMOS. Data were reduced with standard Gemini IRAF procedures. Structural parameters were measured on HST frames, and the stellar content of the clusters was analysed with full-spectrum fitting. Emission-line fluxes were used to estimate reddening, electron temperatures, and abundances for the nebulae. Results. We confirm the presence of 19 star clusters and five H II regions associated with NGC 7793 based on their measured radial velocities and their spectroscopic, photometric, and structural properties. The clusters span a wide range of ages, from several Myr to about seven Gyr, and show metallicities between Fe/H ≈ −0.6 and +0.4. Their effective radii are typically 2–7 pc, comparable to those measured in other spiral galaxies of the Sculptor Group. All emission-line objects have spectra consistent with H II regions of sub-solar metallicity (12 + log(O/H) = 8.2–8.8). Conclusions. This work provides a new spectroscopic census for the selected sample of star clusters and nebulae in NGC 7793. The properties of both populations are similar to those found in other late-type galaxies of the Sculptor Group.
Davoust et al. (Mon,) studied this question.