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A new point of view on the dynamics of the circumstellar nebula M1-67 around the run-away Wolf-Rayet ( WR ) star WR 124 is presented .
We simulated the outbursts of nebulae with different morphologies , to compare the results to the observed dynamical spectra of M1-67 .
We found that it has been interacting with the surrounding ISM and has formed a bow shock due to its high velocity of about 180 ~ { } \mbox { km s } ^ { -1 } relative to the local ISM .
The star is about 1.3 parsec away from the front of this bow shock .
The outbursts that are responsible for the nebula are assumed to be discrete outbursts that occurred inside this bow shock .
The ejecta collide with this bow shock shortly after the outburst .
After the collision , they are dragged away by the pressure of the ISM , along the surface of the bow shock .
The bow shock is oriented in such way that we are looking from the rear into this paraboloid , almost along the main axis .
Evidence for this is given firstly by the fact that the far hemisphere is much brighter than the near hemisphere , secondly by the fact that there is hardly any emission found with radial velocities higher than the star ’ s radial velocity , thirdly by the fact that the star looks to be in the centre of the nebula , as seen from Earth , and finally by the asymmetric overall velocity distribution of the nebula , which indicates higher radial velocities in the centre of the nebula , and lower velocities near the edges .
We find evidence for at least two discrete outbursts that occurred inside this bow shock .
For these outbursts , we find expansion velocities of v _ { \mathrm { exp } } \approx 150 ~ { } \mbox { km s } ^ { -1 } and dynamical timescales of about 0.8 and 2 \times 10 ^ { 4 } yr , which are typical values for LBV outbursts .
We therefore conclude that M1-67 originates from several outbursts that occurred inside the bow shock around WR 124 , during an LBV phase that preceded the current WR phase of the star .