High-resolution Very Large Array observations of 18 MIPSGAL bubbles
  We present radio observations of 18 MIPSGAL bubbles performed at 5 GHz (6 cm)
with the Karl G. Jansky Very Large Array in configuration B and BnA. The
observations were aimed at understanding what kind of information
high-resolution and high-sensitivity radio maps can supply on the circumstellar
envelopes of different kinds of evolved stars and what their comparison with
infrared images with similar resolution can tell us. We found that the 18
bubbles can be grouped into five categories according to their radio
morphology. The three bubbles presenting a central point source in the radio
images all correspond to luminous blue variable star candidates. Eleven bubbles
show an elliptical shape and the total lack of a central object in the radio,
and are likely associated with planetary nebulae. Under this assumption we
derive their distance, their ionized mass and their distribution on the
Galactic plane. We discuss the possibility that the MIPSGAL bubbles catalogue
(428 objects) may contain a large fraction of all Galactic planetary nebulae
located at a distance between 1.4 kpc and 6.9 kpc and lying in the MIPSGAL
field of view. Among the remaining bubbles we identify also a H II region and a
proto-planetary nebula candidate.
