  The chemical tagging technique proposed by Freeman & Bland-Hawthorn (2002) is
based on the idea that stars formed from the same molecular cloud should share
the same chemical signature. Thus, using only the chemical composition of stars
we should be able to re-group the ones that once belonged to the same stellar
aggregate. In Blanco-Cuaresma et al. (2015), we tested the technique on open
cluster stars using iSpec (Blanco-Cuaresma et al. 2014a), we demonstrated their
chemical homogeneity but we found that the 14 studied elements lead to chemical
signatures too similar to reliably distinguish stars from different clusters.
This represents a challenge to the technique and a new question was open: Could
the inclusion of other elements help to better distinguish stars from different
aggregates? With an updated and improved version of iSpec, we derived
abundances for 28 elements using spectra from HARPS, UVES and NARVAL archives
for the open clusters M67 and IC4651, and we found that the chemical signatures
of both clusters are very similar.
