The challenge of clustering stars using their chemical signatures

Séminaire IPAG de Sergio Blanco-Cuaresma (Université de Genève), jeudi 10 novembre 2016 à 11h00, salle Manuel Forestini IPAG

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 using Open Cluster stars using iSpec (Blanco-Cuaresma et al. 2014), 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 ? To find an answer : we improved our tool, iSpec, by performing exhaustive comparison of five well-known radiative transfer codes (SPECTRUM, Turbospectrum, SME, MOOG and Synthe/WIDTH9), and we re-did our Open Cluster analysis considering more than 20 different elements and defying the challenge.