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Local GalaxiesFerguson+98 : Hα emission from HII regions ( ➜ starformation) beyond the optical radius in spiralsHot gas : HII : emission linestrace physical & chemical conditionsN , T e eabundancesLocal GalaxiesThilker+07,Gil de Paz+05 : Galex UV emission from hotyoung stars beyond the optical radius in spiralsE.g. NGC 4625Galex: : FUV deep B-bandH : Lyman, Balmer, Paschen, ….UV opt.NIRseriesHα, , Hβ, H , Hγ,HH,Hδ,…lines from all elements &ionisation stagesalso forbidden * lines, e.g. [OII]*collisionnally de-excitedF(Hα) [erg/s] ~ SFR [M o /yr] under terrestrial conditions,but not in Hyper-UHV in spaceU. Fritze, HD Grad. Days 2008U. Fritze, HD Grad. Days 2008Observations at different wavelengths→ the GALEX SurpriseGALEX – SDSS (Gil de Paz+06)Observations at different wavelengths→ the GALEX SurpriseGALEX – SDSS (Gil de Paz+06)Some galaxies appear much more extended in the UVthan in the optical, HI, and HαHStar formation extends far beyond the optical disk !(= far beyond where the stars are)➜ inside out formation of disks but :Reservoir ???HII regions ??? (but see Ferguson+04)IMF ??? (cf. Kotulla & Fritze, , in prep.)U. Fritze, HD Grad. Days 2008Some galaxies appear Hα (WIYN) much on top of more GALEX extended UV in the UVthan in the optical, HI, and HαHStar formation extends far beyond the optical disk !(= far beyond where the stars are)➜ inside out formation of disks but :Reservoir ???Arp 78HII regions ??? (but see Ferguson+04)IMF ??? (cf. Kotulla & Fritze, , in prep.)U. Fritze, HD Grad. Days 2008M 32NGC 205Local GalaxiesNormal (= big) galaxies : Spirals Sa, Sb, , Sc, SdM 31differential rotation120 km/s ≤ v rot≤ 240 km/srotational velocity ➔ total(= dynamical) massLocal GalaxiesNormal (= big) galaxies : Spirals Sa, Sb, , Sc, SdM 32NGC 205M 31disks : gradients in- color- extinction- metallicity- stellar agedifficult to disentanglerotation curves ➔ Dark Matter halosU. Fritze, HD Grad. Days 2008U. Fritze, HD Grad. Days 20088