Vol. 565
In section 7. Stellar structure and evolution

A VLT/FLAMES survey for massive binaries in Westerlund 1. IV. Wd1-5 - binary product and a pre-supernova companion for the magnetar CXOU J1647-45?

byJ.S. Clark, B. W. Ritchie, F. Najarro, N. Langer, and I. Negueruela A&A 565, A90

Magnetars are highly magnetised neutron stars, some of which are known gamma-ray burst repeaters. Which channels lead to their formation is still under debate. The authors propose that the star Wd1-5 in the cluster Westerlund 1 was a binary companion of the progenitor of the magnetar CXOU J1647-45, before the system was disrupted by the supernova explosion. The abundance pattern observed in WD1-5 indicates contamination from the progenitor of the magnetar.