Bubbling $AdS_{3}$

In the light of the recent Lin, Lunin, Maldacena (LLM) results we investigate $\ft12$-BPS geometries in minimal (and next-to minimal) supergravity in $D=6$ dimensions. In the case of minimal supergravity, solutions are given by fibrations of a two-torus $T^2$ specified by two harmonic functions. For a rectangular torus the two functions are related by a non-linear equation with rare solutions: AdS$^3\times S^3$, the pp-wave and the multi-center string. ``Bubbling'', i.e. superpositions of droplets, is accommodated by allowing the complex structure of the $T^2$ to vary over the base. The analysis is repeated in the presence of a tensor multiplet and similar conclusions are reached with generic solutions describing D1D5 (or their dual fundamental string-momentum) systems. In this framework, the profile of the dual fundamental string-momentum system is identified with the boundaries of the droplets in a two-dimensional plane.