Penrose Limits of the Baryonic D5-brane

The Penrose limits of a D5-brane wrapped on the sphere of AdS5 × S5 and connected to the boundary by N fundamental strings, which is dual to the baryon vertex of the = 4 SU(N) super Yang-Mills theory, are investigated. It is shown that, for null geodesics that lead to the maximally supersymmetric Hpp-wave background, the resulting D5-brane is a 1/2-supersymmetric null brane. For an appropriate choice of radial geodesic, however, the limiting configuration is 1/4-supersymmetric and closely related to the Penrose limit of a flat space BIon.