| Issue |
A&A
Volume 430, Number 1, January IV 2005
|
|
|---|---|---|
| Page(s) | L13 - L16 | |
| Section | Letters | |
| DOI | https://doi.org/10.1051/0004-6361:200400118 | |
| Published online | 12 January 2005 | |
Letter to the Editor
UVES observations of the Canis Major overdensity*
1
ESO - European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago de Chile e-mail: lsbordon@eso.org
2
Universitá di Roma “Tor Vergata”, via Della Ricerca Scientifica 2, Roma, Italy
3
INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo, Trieste, Italy
Received:
21
October
2004
Accepted:
2
December
2004
We present the first detailed chemical abundances for three giant
stars which are candidate members of the Canis Major overdensity, obtained by
using FLAMES-UVES at VLT. The stars, in the background
of the open cluster NGC 2477, have radial velocities compatible
with a membership to this structure. However, due to Galactic disc contamination, radial velocity by itself is unable to firmly
establish membership. The metallicities span the
range ![$\rm -0.5\la [Fe/H] \la +0.1$](/articles/aa/abs/2005/04/aagj211/aagj211_tex_eq1.png)
. Assuming that at least one of
the three stars is indeed a member of CMa implies that this
structure has undergone a high level of chemical processing,
comparable to that of the Galactic disc. The most metal-rich
star of the sample, EIS 6631, displays several abundance ratios which
are remarkably different from those of Galactic stars:
![${\rm [\alpha/Fe]} \sim -0.2$](/articles/aa/abs/2005/04/aagj211/aagj211_tex_eq2.png)
, ![${\rm [Cu/Fe]} \sim +0.25$](/articles/aa/abs/2005/04/aagj211/aagj211_tex_eq3.png)
, ![${\rm [La/Fe]} \sim +0.6$](/articles/aa/abs/2005/04/aagj211/aagj211_tex_eq4.png)
,
![${\rm [Ce/Fe]} \sim +0.8$](/articles/aa/abs/2005/04/aagj211/aagj211_tex_eq5.png)
and ![${\rm [Nd/Fe]}\sim +0.6$](/articles/aa/abs/2005/04/aagj211/aagj211_tex_eq6.png)
. These ratios make it likely
that this star was formed in an external galaxy.
Key words: stars: abundances / stars: atmospheres / galaxies: abundances / galaxies: evolution / galaxies: dwarf
© ESO, 2005
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