The Stellar Wind of MWC 349A

The radial velocities of radio recombination lines from 15 to 20,000 GHz facilitate a kinematic probe of the stellar wind (outflow) from MWC 349A. These data and an earlier fit to the free-free continuum emission determine the radial velocity of the stellar wind out to more than 100 AU. The derived gas flow fits a "beta law" with β = 6 and a terminal velocity of 32 km s-1. The derived mass loss via the wind is about 4 × 10-6 M☉ yr-1 at a radius of 50 AU from the star, comparable to the value derived earlier by Cohen et al. by modeling an image of the 5 GHz emission observed with the Very Large Array. This outflow could also be the evaporation from the circumstellar disk rather than a conventional stellar wind. The stellar recession velocity appears to be about 12 km s-1.