Gil De Paz, ArmandoDíaz Lopez, CristinaZamorano Calvo, JaimeGallego Maestro, JesúsMuñoz Mateos, Juan CarlosPérez González, Pablo GuillermoFunes, José G.Corsini, Enrico Maria2023-06-202023-06-202008978-1-58381-662-2https://hdl.handle.net/20.500.14352/53473Artículo firmado por 21 autores. International Conference on Formation and Evolution of Galaxy Disks (2007. Rome, Italy). We thank the Calar Alto Time Allocation Committee for the generous allocation of time to the CAHA-XUV project.We summarize the main properties of the extended UV (XUV) emission found in roughly 30% of the nearby spiral galaxies observed by the GALEX satellite. Two different classes of XUV disks are identified, the Type 1 XUV disks where significant, structured UV-bright features are found beyond the classical azimuthally-averaged star-formation threshold, and the Type 2 XUV disks, which are characterized by very extended (seven times the area where most of the stellar mass is found), blue ((FUV-K)<5 mag) outer disks. These latter disks are extreme examples of galaxies growing inside-out. The few XUV disks studied in detail to date are rich in H I but relatively poor in molecular gas, have stellar populations with luminosity-weighted ages of ∼1 Gyr, and ionized-gas metal abundances of ∼Z_⊙/10. As part of the CAHA-XUV project we are in the process of obtaining deep multi-wavelength imaging and spectroscopy of 65 XUV-disk galaxies so to determine whether or not these properties are common among XUV disks.engbook parthttp://arxiv.org/abs/0801.2255open access52Spiral galaxiesStar-formationUltraviolet diskEvolutionSpectroscopyAbundancesNGC-4625M83AstrofísicaAstronomía (Física)