2012A&A...538A..60S

Massive stars have a profound effect on the surrounding interstellar medium. They ionize and heat the neutral gas, and with their strong winds they sweep up the gas, forming large HI shells. In this way, they generate a dense shell that provides the physical conditions for the formation of new stars. The aim of this study is to analyze the origin and evolution of the large HI shell GS100-02-41 and its role in triggering star-forming processes.To characterize the shell and its environs, we carried out a multi-wavelength study. We analyzed the HI 21 cm line, the radio continuum, and infrared emission distributions. The analysis of the HI data shows an expanding shell structure centered at (l, b)=(100.6°, -2.04°) in the velocity range from -29 to -51.7km/s. Taking into account noncircular motions, we infer for GS100-02-41 a kinematical distance of 2.8±0.6kpc. Several massive stars belonging to CepOB1 are located in projection within the large HI shell boundaries. The analysis of the radio continuum and infrared data reveals that there is no continuum counterpart of the HI shell. On the other hand, three slightly extended radio continuum sources are observed in projection onto the dense HI shell. From their flux density determinations we infer that they are thermal in nature. An analysis of the HI emission distribution in the environs of these sources shows a region of low emissivity for each of them, which correlates well morphologically with the ionized gas in a velocity range similar to the one where GS100-02-41 is detected. Based on an energy analysis, we conclude that the origin of GS100-02-41 could have been mainly caused by the action of the CepOB1 massive stars located inside the HI shell. The obtained age difference between the HI shell and the HII regions, together with their relative location, lead us to conclude that the ionizing stars could have been created as a consequence of the shell evolution.