OH maser emission toward the young planetary nebula K3-35

Abstract

K3-35 is one of the two planetary nebulae (PNe) where water maser emission has been reported, suggesting that these kind of objets departed from the AGB phase only some decades ago. We present VLA (Very Large Array) observations of the 1720, 1667, 1665 and 1612 MHz OH maser emission from the central region of K3-35. The OH 1665 MHz maser spots are distributed in an elongated structure, along the minor axis of the radio continuum bipolar outflow, and they exhibit high circular polarization suggesting the presence of a toroidal magnetic field in K3-35. An estimate of the magnitude of the magnetic field, derived from the 1665 line, toward this young planetary nebula is ∼ 0.14 mG at a radius of ∼ 250 AU.