Terzan 5: a Fossil Remnant of the Galactic Bulge

Abstract

Terzan 5 is a stellar system located in the Galactic Bulge, at a distance of 5.9 kpc. Recent discoveries show that it hosts two stellar populations with different iron abundance (Δ[Fe/H]=0.5). Such a large difference has been measured only in ω Centauri in the Galactic halo. Moreover no anticorrelation is observed in Terzan 5, hence it is not a genuine globular cluster. The observed chemical patterns are strikingly similar to those observed in the Bulge stars. This suggests that Terzan 5 is a remnant fragment of the Galactic bulge.

4 pages, 6 figures (conference proceedings). "Reading the book of globular clusters with the lens of stellar evolution" (Rome, Nov 2012). To be published in a dedicate volume of the Memorie della Societa' Astronomica Italiana