The far-ultraviolet emission of early-type galaxies
Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, Les Trois Lucs, BP 8, 13376 Marseille Cedex 12, France
Corresponding author: J.-M. Deharveng, firstname.lastname@example.org
Accepted: 12 July 2002
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 color in the range 2 to 5. The spread in is accompanied by a spread in that is mainly attributed to the range of morphological types and luminosities. A large fraction of the objects have red colors, , 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 () 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 color and the Mg2 spectral line index; possible explanations are reviewed. The potential of a more extended UV survey like GALEX is briefly presented.
Key words: stars: AGB and post-AGB / stars: horizontal-branch / galaxies: stellar content / galaxies: elliptical and lenticular, cD / ultraviolet: galaxies
© ESO, 2002