OB associations are the prevailing star forming sites in the Galaxy .
Up to now , the process of how OB associations were formed remained a mystery .
A possible process is self-regulating star formation driven by feedback from massive stars .
However , although a number of observational studies uncovered various signposts of feedback-driven star formation , the effectiveness of such feedback has been questioned .
Stellar and gas kinematics is a promising tool to capture the relative motion of newborn stars and gas away from ionizing sources .
We present high-resolution spectroscopy of stars and gas in the young open cluster NGC 1893 .
Our findings show that newborn stars and the tadpole nebula Sim 130 are moving away from the central cluster containing two O-type stars , and that the timescale of sequential star formation is about 1 Myr within a 9 parsec distance .
The newborn stars formed by feedback from massive stars account for at least 18 per cent of the total stellar population in the cluster , suggesting that this process can play an important role in the formation of OB associations .
These results support the self-regulating star formation model .