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Published online by Cambridge University Press: 24 October 2025
For a planar analytic Hamiltonian system, which has a period annulus limited by a nilpotent center and a homoclinic loop to a nilpotent singularity, we study its analytic perturbation to obtain the number of limit cycles bifurcated from the periodic orbits inside the period annulus. By characterizing the coefficients and their properties of the high-order terms in the expansion of the first-order Melnikov function near the loop, we provide a new way to find more limit cycles. Moreover, we apply these general results to concrete systems, for instance, an
$(m+1)$th-order generalized Liénard system, and an mth-order near-Hamiltonian system with a hyperelliptic Hamiltonian of degree
$6$.
This work is partially supported by the National Key R&D Program of China (Grant No. 2022YFA1005900). The first author is partially supported by the NSF of Zhejiang Province (Grant No. LY24A010 009), by the NNSF of China (Grant Nos. 12471156 and 12371167), and by the Shanghai Frontier Research Center of Modern Analysis. The second author is partially supported by the NNSF of China (Grant No. 11931016). The fourth author is partially supported by the NNSF of China (Grant No. 12471169).