Issue |
A&A
Volume 436, Number 2, June III 2005
|
|
---|---|---|
Page(s) | L9 - L12 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:200500110 | |
Published online | 30 May 2005 |
Letter to the Editor
Sulphur abundances in Terzan 7
1
Liceo L. e S.P.P. S. Pietro al Natisone, Annesso al Convitto Nazionale “Paolo Diacono”, Piazzale Chiarottini 8, Cividale del Friuli (Udine), Italy e-mail: elcaffau@libero.it
2
Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy e-mail: bonifaci@ts.astro.it
3
Dipartimento di Astronomia, Università degli Studi di Trieste, Italy e-mail: faraggiana@ts.astro.it
4
ESO European Southern Observatory – Alonso de Cordova 3107 Vitacura, Santiago, Chile
5
Universitá di Roma 2 “Tor Vergata” – via della Ricerca Scientifica, Rome, Italy e-mail: sbordone@mporzio.astro.it
Received:
1
March
2005
Accepted:
19
April
2005
We present here the first measurements of sulphur abundances
in extragalactic stars. We make use of high resolution spectra,
obtained with UVES at the ESO 8.2 m Kueyen telescope, of three
giants of the Globular Cluster Terzan 7, which belongs
to the Sagittarius dwarf galaxy. We measure the sulphur abundances
using the lines of multiplet 1.
The S/Fe ratios for all three stars are nearly solar, thus
considerably lower than what is found in Galactic stars
of comparable iron content
).
This finding is in keeping with the abundances
of other α-chain elements in this cluster and in
Sagittarius and other dSphs in general.
These low α-chain elements to iron ratios
suggest that Sagittarius and its Globular Clusters
have experienced a low or bursting star-formation rate.
Our sulphur abundances imply
which is comparable to what is
found in many
regions of
similar oxygen content, and is slightly lower
than the solar value (
).
These are also the first measurements of sulphur abundances
in a Globular Cluster, thus a direct comparison of Terzan 7
and Galactic Globular Clusters is not possible yet. However
our analysis suggests that the lines of
multiplet 1 should
be measurable for other Globular Clusters at least down to
a metallicity ~–1.5.
Key words: nucleosynthesis / stars: abundances / globular clusters: individual: Terzan 7 / galaxies: abundances / galaxies: dwarf / galaxies: individual Sgr dSph
© ESO, 2005
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