Two supernova remnants of low radio surface brightness discovered in the Canadian Galactic Plane Survey

Two new supernova remnants (SNRs), G85.4+0.7 and G85.9-0.6, superimposed on the radio source W 80, have been discovered in the radio continuum data from the Canadian Galactic Plane Survey(CGPS). Both SNRs consist of a thin incomplete radio shell surrounding a weak, extended X-ray source. G85.4+0.7 has a thin non-thermal shell of diameter approximate to 0.4 degrees lying within a thermal shell whose diameter is approximate to0.6 degrees. Its radio surface brightness at 1 GHz is Sigma (1) (GHz) less than or equal to 1 x 10(-22) Watt m(-2) Hz(-1) sr(-1). It is located within a large H I bubble, whose systemic velocity, v(LSR) = -12 km s(-1), implies a distance of 3.8 kpc. Two B1 stars detected within this bubble are most likely part of the OB association which formed it. The diameter of the H I bubble is about 100 pc. The SNR has a diameter of about 30 pc and probably is the result of a type II explosion of an early B star approximate to 6300 years ago. G85.9-0.6 has a radio surface brightness of Sigma (1) (GHz) less than or equal to 2 x 10(-22) Watt m(-2) Hz(-1) sr(-1). No H I features corresponding to the SNR have been detected. This, and the low radio and X-ray brightnesses, suggest expansion in a low-density medium. The SNR may lie in the low-density region between the local and Perseus spiral arms, at a distance of about 5 kpc. Its diameter would then be similar to 35 pc.