A double detached shell around a post-red supergiant: IRAS 17163-3907, the Fried Egg nebula E. Lagadec, A. A. Zijlstra, R. D. Oudmaijer, T. Verhoelst, N. L. J. Cox, R. Szczerba, D. Mékarnia and H. van Winckel A&A, 534 (2011) L10 Published online: 17 October 2011 DOI: 10.1051/0004-6361/201117521