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We have used the greatly enhanced spectral capabilities of the Expanded VeryLarge Array to observe both the 22.3 GHz continuum emission and the H66{\alpha}recombination line toward the well-studied Galactic emission-line star MWC349A. The continuum flux density is found to be 411 $\pm$ 41 mJy in goodagreement with previous determinations. The H66{\alpha} line peak intensity isabout 25 mJy, and the average line-to-continuum flux ratio is about 5%, asexpected for local thermodynamic equilibrium conditions. This shows that theH66{\alpha} recombination line is not strongly masing as had previously beensuggested, although a moderate maser contribution could be present. TheHe66{\alpha} recombination line is also detected in our observations; therelative strengths of the two recombination lines yield an ionized helium toionized hydrogen abundance ratio y+ = 0.12 $\pm$ 0.02. The ionized heliumappears to share the kinematics of the thermally excited ionized hydrogen gas,so the two species are likely to be well mixed. The electron temperature of theionized gas in MWC 349A deduced from our observations is 6,300 $\pm$ 600 K.

Expanded Very Large Array observations of the H66{\alpha} and He66{\alpha} recombination lines toward MWC 349A