Galactic ring nebulae associated with Wolf-Rayet stars. II. M 1-67 : a nebula braked by the interstellar medium.

It is pointed out that the nebula M1-67 is characterized by two uncommon properties. First, if it is a planetary nebula, it is the only one known with a WN nucleus. Second, both the central star 209 BAC, often called Merrill's star, and the nebula are moving at a high heliocentric velocity, approximately plus 200 km/s. The considered investigation concerning M1-67, takes into account a photographic study conducted with a narrow band interference filter and the mapping of the radial velocity of the nebula with a Fabry-Perot interferometer. It is concluded that the nebula M1-67, like planetary nebula, is made of matter, which has been ejected from the central star. It is thought possible that the star had ejected material prior to the oldest component currently observed and that the earlier ejecta have dissipated and can no longer be detected. An illustration is given that nebular braking is possible.