X-shooter Observations of Main-sequence Stars in the Globular Cluster NGC 2808: First Chemical Tagging of a He-normal and a He-rich Dwarf

We observed two main sequence stars in the globular cluster NGC 2808, using X-shooter. We selected one of the targets on the blue main sequence (bMS) and one on the red main sequence (rMS) and measured abundances for several light elements that are expected to be different in stars of first and second generations in globular clusters. The differences between the bMS and the rMS stars amply exceed the errors and is in agreement with a difference in products of hydrogen burning at high temperature. More data are required to put the findings on more solid basis and to try to distinguish between the different models proposed to explain the formation of globular clusters. Data collected under ESO programme 084.D-0070, as part of the Italian GTO for X-shooter, originally organised by Roberto Pallavicini, to whom we are grateful and to whom our work is dedicated.