Was star formation in the OB associations , LH 51 and LH 54 , triggered by the growth of the superbubble DEM 192 ?
To examine this possibility , we investigate the stellar contents and star formation history , and model the evolution of the shell .
H-R diagrams constructed from UBV photometry and spectral classifications indicate highly coeval star formation , with the entire massive star population having an age of \lesssim 2–3 Myr .
However , LH 54 is constrained to an age of \sim 3 Myr by the presence of a WR star , and the IMF for LH 51 suggests a lower-mass limit implying an age of 1–2 Myr .
There is no evidence of an earlier stellar population to create the superbubble , but the modeled shell kinematics are consistent with an origin due to the strongest stellar winds of LH 54 .
It might therefore be possible that LH 54 created the superbubble , which in turn may have triggered the creation of LH 51 .
Within the errors , the spatial distribution of stellar masses and IMF appear uniform within the associations .

We reinvestigate the estimates for stellar wind power L _ { w } ( t ) , during the H-burning phase , and note that revised mass-loss rates yield a significantly different form for L _ { w } ( t ) , and may affect stellar evolution timescales .
We also model superbubble expansion into an ambient medium with a sudden , discontinuous drop in density , and find that this can easily reproduce the anomalously high shell expansion velocities seen in many superbubbles .