Spiral density wave generation by vortices in Keplerian flows G. Bodo, G. Chagelishvili, G. Murante, A. Tevzadze, P. Rossi and A. Ferrari A&A, 437 1 (2005) 9-22 Published online: 10 June 2005 DOI: 10.1051/0004-6361:20041046