The composition of circumstellar gas and dust in 51 Oph M. E. van den Ancker, G. Meeus, J. Cami, L. B. F. M. Waters and C. Waelkens A&A, 369 2 (2001) L17-L21 Published online: 15 April 2001 DOI: 10.1051/0004-6361:20010245