ROTATION IN THE IONIZED ENVELOPE OF MWC-349A

Using the Very Large Array in the A configuration we mapped the H92alp ha recombination line and the adjacent continuum emission at 3.6 cm fr om the peculiar emission-line star MWC 349A. The recombination line em ission is consistent with local thermodynamic equilibrium conditions. Our data resolves spatially for the first time the kinematic structure of this envelope. The observed motions can be explained in terms of a bipolar outflow undergoing significant rotation. The inclination angl e of the outflow axis with respect to the plane of the sky is estimate d to be about 15-degrees. Angular momentum conservation arguments indi cate that this rotating gas cannot have originated from the stellar su rface and most probably is photoevaporating from a disk around the sta r. Assuming Keplerian rotation, we estimate the mass of the star to be approximately 30 M.. The presence of a rotating disk in association w ith MWC 349A favors a pre-main-sequence nature for this object.