2004A&A...422L...9H


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.27CET22:35:55

2004A&A...422L...9H - Astronomy and Astrophysics, volume 422, L9-12 (2004/7-4)

The extended star formation history of ω Centauri.

HILKER M., KAYSER A., RICHTLER T. and WILLEMSEN P.

Abstract (from CDS):

For the first time, the abundances of a large sample of subgiant and turn-off region stars in ω Centauri have been measured, the data base being medium resolution spectroscopy from FORS2 at the VLT. Absolute iron abundances were derived for ∼400 member stars from newly defined line indices with an accuracy of ±0.15dex. The abundances range between -2.2<[Fe/H]←0.7dex, resembling the large metallicity spread found for red giant branch stars. The combination of the spectroscopic results with the location of the stars in the colour magnitude diagram has been used to estimate ages for the individual stars. Whereas most of the metal-poor stars are consistent with a single old stellar population, stars with abundances higher than [Fe/H]≃-1.3dex are younger. The total age spread in ω Cen is about 3Gyr. The monotonically increasing age-metallicity relation seems to level off above [Fe/H]≃-1.0dex. Whether the star formation in ω Cen occured continuously or rather episodically has to be shown by combining more accurate abundances with highest quality photometry.

Abstract Copyright:

Journal keyword(s): stars: abundances - globular clusters: individual: ω Cen, M 55 - galaxies: dwarf - galaxies: nuclei

Simbad objects: 2

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Number of rows : 2

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3072 0
2 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 776 0

    Equat.    Gal    SGal    Ecl

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2021.02.27-22:35:55

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