Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-09-11
Astrophys.J.597:L21-L24,2003
Astronomy and Astrophysics
Astrophysics
4 pages, 3 figures, accepted for publication in ApJ Letters
Scientific paper
10.1086/379658
We present central CaT, PaT, and CaT* indices for a sample of fifteen dwarf elliptical galaxies (dEs). Twelve of these have CaT* ~ 7 A and extend the negative correlation between the CaT* index and central velocity dispersion sigma, which was derived for bright ellipticals (Es), down to 20 < sigma < 55 km/s. For five dEs we have independent age and metallicity estimates. Four of these have CaT* ~ 7 A, much higher than expected from their low metallicities (-1.5 < [Z/H] < -0.5). The observed anti-correlation of CaT* as a function of sigma or Z is in flagrant disagreement with theory. We discuss some of the amendments that have been proposed to bring the theoretical predictions into agreement with the observed CaT*-values of bright Es and how they can be extended to incorporate also the observed CaT*-values of dEs. Moreover, 3 dEs in our sample have CaT* ~ 5 A, as would be expected for metal-poor stellar systems. Any theory for dE evolution will have to be able to explain the co-existence of low-CaT* and high-CaT* dEs at a given mean metallicity. This could be the first direct evidence that the dE population is not homogeneous, and that different evolutionary paths led to morphologically and kinematically similar but chemically distinct objects.
de Rijcke Sven
Dejonghe Herwig
Hau George K. T.
Michielsen Dolf
Zeilinger Werner W.
No associations
LandOfFree
The puzzlingly large Ca II triplet absorption in dwarf elliptical galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The puzzlingly large Ca II triplet absorption in dwarf elliptical galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The puzzlingly large Ca II triplet absorption in dwarf elliptical galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-109168