A note on D-branes of odd codimensions from noncommutative tachyons

On a noncommutative space of rank-1, we construct a codimension-one soliton explicitly and, in the context of noncommutative bosonic open string field theory, identify it with the D24-brane. We compute the tension of the prop osed D24-brane, yielding an exact Value and show that it is related to the tension of the codimension-two D23-brane by the string T-duality. This reso lves an apparent puzzle posed by the result of Harvey et al. and proves tha t the T-duality is a gauge symmetry; in particular, at strong noncommutativ ity, it is part of the U(infinity) gauge symmetry on the worldvolume. We al so apply the result to non-BPS D-branes in superstring theories and argue t hat the codimension-one soliton gives rise to new descent relations among t he non-BPS D-branes in type IIA and type IIB string theories via T-duality. (C) 2000 Published by Elsevier Science B.V.