期刊
ASTRONOMY & ASTROPHYSICS
卷 393, 期 3, 页码 843-854出版社
E D P SCIENCES
DOI: 10.1051/0004-6361:20021082
关键词
stars : AGB and post-AGB; stars : horizontal-branch; galaxies : stellar content; galaxies : elliptical and lenticular, cD; ultraviolet : galaxies
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 Mg-2 spectral line index; possible explanations are reviewed. The potential of a more extended UV survey like GALEX is briefly presented.
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