Discovery of a double ring in the core of η Carinae S. Hony, C. Dominik, L. B. F. M. Waters, V. Icke, G. Mellema, R. van Boekel, A. de Koter, P. M. Morris, M. Barlow, P. Cox and H. U. Käufl A&A, 377 1 (2001) L1-L4 Published online: 15 October 2001 DOI: 10.1051/0004-6361:20011168