In a look over the stars seen in the Hipparcos data and a copy of the Sky catalogue 2000.0 I have found the same effect where ripples of gas and dust loop out of the midplane and back getting in the way of relatively distant <1000Pc blue stars in the nearby associations.

It appears that the ripple effect is a feature of gravitational interaction but may have a much more mundane cause. The likely culprit is the tidal interaction of the LMC & SMC galaxies which are massive enough to distort the gas & dust in the disc out of plane but not enough to produce a tidal tail because the bulk disc is far to massive.

The next question is how long the interaction between the LMC/SMC and milky way has been going on. From what I can see so far, the MW. has bypassed the Magellanic clouds, wrapped up the LMC barred spiral into a deinoflagellate shape, and turned the SMC into a tidal tail and is now dragging both galaxies behind us with both likely to fall back onto the disc in the future.

Be interesting to see.

Have a nice day: Ag