Astronomy and Astrophysics, volume 393, 843-854 (2002/10-3)
The far-ultraviolet emission of early-type galaxies.
DEHARVENG J.-M., BOSELLI A. and DONAS J.
Abstract (from CDS):
We have assembled a UV-flux selected sample of 82 early-type galaxies and collected additional information at other wavelengths. These data confirm a large spread of the UV-V color in the range 2 to 5. The spread in UV-V is accompanied by a spread in B-V that is mainly attributed to the range of morphological types and luminosities. A large fraction of the objects have red colors, UV-V=4±0.4, corresponding to a weak UV-upturn as observed with IUE. If the current interpretation for the UV emission from early-type galaxies is applicable to our sample, the PAGB (Post-Asymptotic Giant Branch) tracks are the most common evolution path for the low-mass stars responsible for the UV emission. A small number of very blue (UV-V<1.4) objects have been found that can be reasonably interpreted as harbouring some low level of star formation. In contrast to a previous sample based on IUE observations, no correlation is found between the UV-V color and the Mg2 spectral line index; possible explanations are reviewed. The potential of a more extended UV survey like GALEX is briefly presented.
stars: AGB and post-AGB - stars: horizontal-branch - galaxies: stellar content - galaxies: elliptical and lenticular, cD - ultraviolet: galaxies