The nature of the light variability of the silicon star HR 7224 J. Krtička, Z. Mikulášek, G. W. Henry, J. Zverko, J. Žižňovský, J. Skalický and P. Zvěřina A&A, 499 2 (2009) 567-577 Published online: 27 March 2009 DOI: 10.1051/0004-6361/200811123