%0 Book Section
%T Extended UV (XUV) Emission in Nearby Galaxy Disks
publisher Astronomical Society of the Pacific
%D 2008
%U 978-1-58381-662-2
%@ https://hdl.handle.net/20.500.14352/53473
%X 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.
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