2022A&A...668A..44S

Aims. The goal of this study is to analyze the H I supershell GS 121-05-037 and its role in triggering star formation. Methods. To characterize the supershell, we analyzed the H I 21-cm line and the far-infrared emission distributions. In addition, to study the star formation processes related to GS 121-05-037, we used the Gaia survey, together with spectrophotometric calculations, and derived a method to look for massive OB-type stars. Results. The H I characterization of GS 121-05-037 shows an expanding structure centered at (l, b) ∼ (121°.3, -4°.8) in the velocity range from -47.8 to -25.2km s^–1. It is located at 3.2 ± 1.0 kpc from the Sun and has a kinetic energy of E_k= (2.1 ± 1.3) × 10⁵⁰ erg. GS 121 -05-037 presents, in the H I emission distribution, an open morphology toward the Galactic halo. The analysis of the IR emission reveals the presence of 32 HII regions seen projected into the borders of GS 121-05-037. A spectrophotometric analysis to look for the ionizing stars of these regions reveals that 12 of them would be located at a similar distance to GS 121-05-037. Conclusions. The relative location between GS 121-05-037 and the HII regions, together with their age difference, led us to conclude that the ionizing stars could have been created due to the expansion of the H I supershell. On the other hand, the HII regions located on the interface of two or more supershells could have originated from the collision of the H I structures. Finally, the open morphology of GS 121 -05-037 toward the halo suggests that this large structure could be a Galactic chimney.