Abstract

A small ring-like radio source (G 79.29+0.46) has been discovered in the Cygnus X region from observations made with the DRAO Synthesis Telescope. The shell, ~ 4(') in diameter, has a flux density of ~ 550 mJy at 1.42 GHz. Observations at three frequencies (1.49, 4.86 and 8.44 GHz) with the VLA have confirmed that the shell source is thermal in nature. A central radio source with a radio spectrum indicative of mass outflow was also detected. A heavily reddened optical counterpart of the latter has been found. A quick-look optical spectrum of this star (m_R ~ 15.4(m) ) in the 550 - 750 nm region shows only a heavily reddened continuum and a strong Hα emission line. Extended wings of this line correspond to a wind velocity of ~ 1400 km s(-1) . Observations at DRAO of the 21-cm line of atomic hydrogen indicate accelerated atomic gas associated with the ionized shell, and a shell expansion velocity of ~ 70 km s(-1) . IRAS infrared data show the presence of warm dust (T ~ 65 K) in the ionized shell, and hotter dust (T > 125 K) associated with the central star and its wind. A consideration of all the observational data suggests a very luminous central star (M_b ~ -11(m) ) at a distance of ~ 2 kpc, having an effective temperature of ~ 25,000 K. It is suggested that it may be a member of the Luminous Blue Variable class. The age of the shell, having a mass of ~ 15 M_sun, is estimated to be ~ 10(4) yr.