Stellar Structures in Galaxies: insights from the local universe

Galaxies in the local universe are a fossil record of events in the distant universe and present critical constraints for examining models of formation and evolution of galaxies. Based on the Spitzer Survey of Stellar Structure in Galaxies (S4G) database, we study the stellar light that is typically associated with different stellar structures (such as bulge, disk, bar, spiral arms) in an effort to construct a local reference for stellar structure studies. S4G is one of the major legacy surveys of the post-cryogenic campaign of Spitzer and is the largest, deepest and most homogenous mid-IR survey of the nearby Universe to date. With a surface brightness limit at 3.6 um of 27 mag/arcsec^2, this survey is unique in its capability of probing stellar surface densities down to << 1 M_Sun/pc^2, which is unachievable from the ground. I will show a number of discoveries we have made within this data set, including the characterization of bars, rings and truncated disks in the nearby universe. Combined with deep optical follow-up, an unprecedented opportunity opens up to complement a stellar mass census with a detailed analysis of the stellar populations in stellar structures. With this in mind my team at the Valongo Observatory, we have initiated an observational campaign using the Goodman imager on SOAR to go after S4G galaxies in the southern sky: the Census of Austral Nearby GAlaxies (CANGA). The CANGA survey, covering all griz bands, complements the exquisite work that has been performed by the Sloan Digital Sky Server (SDSS) in the northern hemisphere, but largely surpasses its sensitivity. CANGA provides us with an unprecedented opportunity to complement S4G’s mass census with a spatially-resolved analysis of stellar populations at the 10s-to-100 pc-scale of key stellar structures in nearby galaxies.