In this paper we investigate the operator
Hβ=−Δ−βδ(⋅−Γ) in L2(R2), where
β>0 and Γ is a closed C4 Jordan curve in R2. We
obtain the asymptotic form of each eigenvalue of Hβ as β tends
to infinity. We also get the asymptotic form of the number of negative
eigenvalues of Hβ in the strong coupling asymptotic regime.Comment: amstex, 15 page