The goal of this study is to analyse a set of four shells and their potential role in triggering star formation. We analysed the 21-cm line and far-infrared emission distributions to characterize the four shells. To investigate star formation associated with these shells, we identified massive OB-type star candidates using Gaia data and a spectrophotometric method. The and 8. 4 times 10⁴8 erg. Some of the shells appear to be in collision with each other. The analysis of the IR emission reveals the presence of 28 characterisation of the four shells reveals that they are expanding structures, with expansion velocities ranging from 6 to 9 ̨ms, and kinetic energies between 2. 5 times 10 48 regions seen projected into the borders of the shells, some of them located at the interfaces of two shells. The spectrophotometric analysis used to identify ionising star candidates in these regions indicates a distance of 2. 7 ± 0. 5 kpc for 27 of the regions. Since their radio recombination line (RRL) velocities are consistent with the systemic velocities of the shells, we can infer that the shells are located at the same distance. The distribution of 27 regions along the borders of four shells is consistent with a scenario in which the massive stars responsible for their ionisation may have formed as a consequence of the shells’ expansion and, in some cases, their collision.
Suad et al. (Tue,) studied this question.