Expanding shells around young clusters – S 171/Be 59,

Context. Some HII regions that surround young stellar clusters are bordered by molecular shells appear to expand at a rate inconsistent with our current model simulations. In this study we focus on the dynamics of Sharpless 171 (including NGC 7822), which surrounds cluster Berkeley 59. Aims. We aim compare velocity pattern over shell mean radial for estimates expansion velocities different structures, and match observed properties Methods. Optical spectra 27 stars located in 59 were collected Nordic Telescope, number structures scattered entire region mapped 13 CO(1–0) Onsala Space Observatory. Results. obtained MK classes cluster’s stars. At least four O found be spectroscopic binaries, addition one triplet system. From these data obtain cluster. CO identify three expanding relative moderate (4 km s –1 ), high (12 between. The high-velocity cloudlets extend larger radius less massive than low-velocity cloudlets. performed simulation understand evolution complex. Conclusions. Our complex demonstrates individual components can explained as driven winds from members. However, relatively simple produces single component. Modelling propagation fragments through uniform interstellar medium dense detached decelerated efficiently itself. They reach greater distances retain higher shell.