Evidence for a co-moving sub-stellar companion of GQ Lup R. Neuhäuser, E. W. Guenther, G. Wuchterl, M. Mugrauer, A. Bedalov and P. H. Hauschildt A&A, 435 1 (2005) L13-L16 Published online: 25 April 2005 DOI: 10.1051/0004-6361:200500104