Issue |
A&A
Volume 393, Number 3, October III 2002
|
|
---|---|---|
Page(s) | 843 - 854 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20021082 | |
Published online | 01 October 2002 |
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, jean-michel.deharveng@astrsp-mrs.fr
Received:
20
March
2002
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
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