The potential of a configuration of two Dirichlet branes for which the
number of ND-directions is eight is determined, Depending on whether
one of the branes is an anti-brane or a brane, the potential vanishes
or is twice as large as the dilaton-gravitational potential, This is s
hown to be related to the fact that a fundamental string is created wh
en two such branes cross. Special emphasis is given to the D0-D8 syste
m, for which an interpretation of these results in terms of the massiv
e IIA supergravity is presented. It is also shown that the branes cann
ot move non-adiabatically in the transverse direction, The configurati
on of a zero-brane and an orientifold 8-plane is analyzed in a similar
way, and the implications for the type IA-heterotic duality and the h
eterotic matrix theory are discussed. (C) 1998 Elsevier Science B.V.