Evidence of convective rolls in a sunspot penumbra V. Zakharov, J. Hirzberger, T. L. Riethmüller, S. K. Solanki and P. Kobel A&A, 488 2 (2008) L17-L20 Published online: 23 July 2008 DOI: 10.1051/0004-6361:200810266