The close circumstellar environment of the semi-regular S-type star π1 Gruis S. Sacuto, A. Jorissen, P. Cruzalèbes, O. Chesneau, K. Ohnaka, A. Quirrenbach and B. Lopez A&A, 482 2 (2008) 561-574 Published online: 20 February 2008 DOI: 10.1051/0004-6361:20078306