Radio continuum and recombination line observations of the polypolar planetary nebula NGC 2440

H92 alpha and He92 alpha recombination lines and lambda 3.6 cm continuum observations have been carried out with the Very Large Array (synthesized beam 6.'8 x 4.'2, PA 74 degrees) toward the polypolar planetary nebula NGC 2440. The H92 alpha and He92 alpha lines have been detected, for the first time in this nebula, over a region of theta similar or equal to 14' around its geometric center. The lambda 3.6 cm continuum emission is detected over a region of similar or equal to 65' x 40', similar in extent to the optical emission. Physical parameters of the nebula have been derived for the region in which the recombination lines were detected. From the line to continuum ratio, an electron temperature of similar or equal to 16,000 K and a single ionized helium abundance Y(+) similar or equal to 0.14 are obtained. A relative extinction map of NGC 2440 has also been obtained from the ratio of the lambda 3.6 cm continuum acid Ha images. A higher relative extinction in the central region traces the dense and dusty environment of an apparent central 'toroid.' The velocity field obtained from the H92a line suggests that the central toroidal structure has a distorted, noncircular shape. The polypolar characteristics of this nebula are discussed and compared with those of similar objects.